When starting multi-core loongarch virtualization on loongarch physical machine, loading livepatch on the physical machine will cause an error similar to the following: [ 411.686289] livepatch: klp_try_switch_task: CPU 31/KVM:3116 has an unreliable stack
The specific test steps are as follows: 1.Start a multi-core virtual machine on a physical machine
2.Enter the following command on the physical machine to turn on the debug switch: echo "file kernel/livepatch/transition.c +p" > /sys/kernel/debug/\ dynamic_debug/control
3.Load livepatch: modprobe livepatch-sample
Through the above steps, similar prints can be viewed in dmesg.
The reason for this issue is that the code of the kvm_exc_entry function was copied in the function kvm_loongarch_env_init. When the cpu needs to execute kvm_exc_entry, it will switch to the copied address for execution. The new address of the kvm_exc_entry function cannot be recognized in ORC, which eventually leads to the arch_stack_walk_reliable function returning an error and printing an exception message.
To solve the above problems, we directly compile the switch.S file into the kernel instead of the module. In this way, the function kvm_exc_entry will no longer need to be copied.
changlog: V2<-V1: 1.Rollback the modification of function parameter types such as kvm_save_fpu. In the asm-prototypes.h header file, only the parameter types it depends on are included
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org
Xianglai Li (2): LoongArch: KVM: Compile the switch.S file directly into the kernel LoongArch: KVM: fix "unreliable stack" issue
arch/loongarch/Kbuild | 2 +- arch/loongarch/include/asm/asm-prototypes.h | 21 +++++++++++++ arch/loongarch/include/asm/kvm_host.h | 3 -- arch/loongarch/kvm/Makefile | 2 +- arch/loongarch/kvm/main.c | 35 ++------------------- arch/loongarch/kvm/switch.S | 24 +++++++++++--- 6 files changed, 45 insertions(+), 42 deletions(-)
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
If we directly compile the switch.S file into the kernel, the address of the kvm_exc_entry function will definitely be within the DMW memory area. Therefore, we will no longer need to perform a copy relocation of kvm_exc_entry.
Based on the above description, compile switch.S directly into the kernel, and then remove the copy relocation execution logic for the kvm_exc_entry function.
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn --- Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/Kbuild | 2 +- arch/loongarch/include/asm/asm-prototypes.h | 21 +++++++++++++ arch/loongarch/include/asm/kvm_host.h | 3 -- arch/loongarch/kvm/Makefile | 2 +- arch/loongarch/kvm/main.c | 35 ++------------------- arch/loongarch/kvm/switch.S | 22 ++++++++++--- 6 files changed, 43 insertions(+), 42 deletions(-)
diff --git a/arch/loongarch/Kbuild b/arch/loongarch/Kbuild index beb8499dd8ed..1c7a0dbe5e72 100644 --- a/arch/loongarch/Kbuild +++ b/arch/loongarch/Kbuild @@ -3,7 +3,7 @@ obj-y += mm/ obj-y += net/ obj-y += vdso/
-obj-$(CONFIG_KVM) += kvm/ +obj-$(subst m,y,$(CONFIG_KVM)) += kvm/
# for cleaning subdir- += boot diff --git a/arch/loongarch/include/asm/asm-prototypes.h b/arch/loongarch/include/asm/asm-prototypes.h index 704066b4f736..e8ce153691e5 100644 --- a/arch/loongarch/include/asm/asm-prototypes.h +++ b/arch/loongarch/include/asm/asm-prototypes.h @@ -20,3 +20,24 @@ asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_ struct pt_regs *regs, int (*fn)(void *), void *fn_arg); + +struct kvm_run; +struct kvm_vcpu; + +void kvm_exc_entry(void); +int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu); + +struct loongarch_fpu; + +#ifdef CONFIG_CPU_HAS_LSX +void kvm_save_lsx(struct loongarch_fpu *fpu); +void kvm_restore_lsx(struct loongarch_fpu *fpu); +#endif + +#ifdef CONFIG_CPU_HAS_LASX +void kvm_save_lasx(struct loongarch_fpu *fpu); +void kvm_restore_lasx(struct loongarch_fpu *fpu); +#endif + +void kvm_save_fpu(struct loongarch_fpu *fpu); +void kvm_restore_fpu(struct loongarch_fpu *fpu); diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h index e4fe5b8e8149..1a1be10e3803 100644 --- a/arch/loongarch/include/asm/kvm_host.h +++ b/arch/loongarch/include/asm/kvm_host.h @@ -85,7 +85,6 @@ struct kvm_context { struct kvm_world_switch { int (*exc_entry)(void); int (*enter_guest)(struct kvm_run *run, struct kvm_vcpu *vcpu); - unsigned long page_order; };
#define MAX_PGTABLE_LEVELS 4 @@ -347,8 +346,6 @@ void kvm_exc_entry(void); int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu);
extern unsigned long vpid_mask; -extern const unsigned long kvm_exception_size; -extern const unsigned long kvm_enter_guest_size; extern struct kvm_world_switch *kvm_loongarch_ops;
#define SW_GCSR (1 << 0) diff --git a/arch/loongarch/kvm/Makefile b/arch/loongarch/kvm/Makefile index cb41d9265662..fe665054f824 100644 --- a/arch/loongarch/kvm/Makefile +++ b/arch/loongarch/kvm/Makefile @@ -11,7 +11,7 @@ kvm-y += exit.o kvm-y += interrupt.o kvm-y += main.o kvm-y += mmu.o -kvm-y += switch.o +obj-y += switch.o kvm-y += timer.o kvm-y += tlb.o kvm-y += vcpu.o diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c index 80ea63d465b8..67d234540ed4 100644 --- a/arch/loongarch/kvm/main.c +++ b/arch/loongarch/kvm/main.c @@ -340,8 +340,7 @@ void kvm_arch_disable_virtualization_cpu(void)
static int kvm_loongarch_env_init(void) { - int cpu, order, ret; - void *addr; + int cpu, ret; struct kvm_context *context;
vmcs = alloc_percpu(struct kvm_context); @@ -357,30 +356,8 @@ static int kvm_loongarch_env_init(void) return -ENOMEM; }
- /* - * PGD register is shared between root kernel and kvm hypervisor. - * So world switch entry should be in DMW area rather than TLB area - * to avoid page fault reenter. - * - * In future if hardware pagetable walking is supported, we won't - * need to copy world switch code to DMW area. - */ - order = get_order(kvm_exception_size + kvm_enter_guest_size); - addr = (void *)__get_free_pages(GFP_KERNEL, order); - if (!addr) { - free_percpu(vmcs); - vmcs = NULL; - kfree(kvm_loongarch_ops); - kvm_loongarch_ops = NULL; - return -ENOMEM; - } - - memcpy(addr, kvm_exc_entry, kvm_exception_size); - memcpy(addr + kvm_exception_size, kvm_enter_guest, kvm_enter_guest_size); - flush_icache_range((unsigned long)addr, (unsigned long)addr + kvm_exception_size + kvm_enter_guest_size); - kvm_loongarch_ops->exc_entry = addr; - kvm_loongarch_ops->enter_guest = addr + kvm_exception_size; - kvm_loongarch_ops->page_order = order; + kvm_loongarch_ops->exc_entry = (void *)kvm_exc_entry; + kvm_loongarch_ops->enter_guest = (void *)kvm_enter_guest;
vpid_mask = read_csr_gstat(); vpid_mask = (vpid_mask & CSR_GSTAT_GIDBIT) >> CSR_GSTAT_GIDBIT_SHIFT; @@ -414,16 +391,10 @@ static int kvm_loongarch_env_init(void)
static void kvm_loongarch_env_exit(void) { - unsigned long addr; - if (vmcs) free_percpu(vmcs);
if (kvm_loongarch_ops) { - if (kvm_loongarch_ops->exc_entry) { - addr = (unsigned long)kvm_loongarch_ops->exc_entry; - free_pages(addr, kvm_loongarch_ops->page_order); - } kfree(kvm_loongarch_ops); }
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index f1768b7a6194..93845ce53651 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -5,6 +5,7 @@
#include <linux/linkage.h> #include <asm/asm.h> +#include <asm/page.h> #include <asm/asmmacro.h> #include <asm/loongarch.h> #include <asm/regdef.h> @@ -100,10 +101,18 @@ * - is still in guest mode, such as pgd table/vmid registers etc, * - will fix with hw page walk enabled in future * load kvm_vcpu from reserved CSR KVM_VCPU_KS, and save a2 to KVM_TEMP_KS + * + * PGD register is shared between root kernel and kvm hypervisor. + * So world switch entry should be in DMW area rather than TLB area + * to avoid page fault reenter. + * + * In future if hardware pagetable walking is supported, we won't + * need to copy world switch code to DMW area. */ .text .cfi_sections .debug_frame SYM_CODE_START(kvm_exc_entry) + .p2align PAGE_SHIFT UNWIND_HINT_UNDEFINED csrwr a2, KVM_TEMP_KS csrrd a2, KVM_VCPU_KS @@ -190,8 +199,8 @@ ret_to_host: kvm_restore_host_gpr a2 jr ra
-SYM_INNER_LABEL(kvm_exc_entry_end, SYM_L_LOCAL) SYM_CODE_END(kvm_exc_entry) +EXPORT_SYMBOL(kvm_exc_entry)
/* * int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu) @@ -215,8 +224,8 @@ SYM_FUNC_START(kvm_enter_guest) /* Save kvm_vcpu to kscratch */ csrwr a1, KVM_VCPU_KS kvm_switch_to_guest -SYM_INNER_LABEL(kvm_enter_guest_end, SYM_L_LOCAL) SYM_FUNC_END(kvm_enter_guest) +EXPORT_SYMBOL(kvm_enter_guest)
SYM_FUNC_START(kvm_save_fpu) fpu_save_csr a0 t1 @@ -224,6 +233,7 @@ SYM_FUNC_START(kvm_save_fpu) fpu_save_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_save_fpu) +EXPORT_SYMBOL(kvm_save_fpu)
SYM_FUNC_START(kvm_restore_fpu) fpu_restore_double a0 t1 @@ -231,6 +241,7 @@ SYM_FUNC_START(kvm_restore_fpu) fpu_restore_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_fpu) +EXPORT_SYMBOL(kvm_restore_fpu)
#ifdef CONFIG_CPU_HAS_LSX SYM_FUNC_START(kvm_save_lsx) @@ -239,6 +250,7 @@ SYM_FUNC_START(kvm_save_lsx) lsx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lsx) +EXPORT_SYMBOL(kvm_save_lsx)
SYM_FUNC_START(kvm_restore_lsx) lsx_restore_data a0 t1 @@ -246,6 +258,7 @@ SYM_FUNC_START(kvm_restore_lsx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lsx) +EXPORT_SYMBOL(kvm_restore_lsx) #endif
#ifdef CONFIG_CPU_HAS_LASX @@ -255,6 +268,7 @@ SYM_FUNC_START(kvm_save_lasx) lasx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lasx) +EXPORT_SYMBOL(kvm_save_lasx)
SYM_FUNC_START(kvm_restore_lasx) lasx_restore_data a0 t1 @@ -262,10 +276,8 @@ SYM_FUNC_START(kvm_restore_lasx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lasx) +EXPORT_SYMBOL(kvm_restore_lasx) #endif - .section ".rodata" -SYM_DATA(kvm_exception_size, .quad kvm_exc_entry_end - kvm_exc_entry) -SYM_DATA(kvm_enter_guest_size, .quad kvm_enter_guest_end - kvm_enter_guest)
#ifdef CONFIG_CPU_HAS_LBT STACK_FRAME_NON_STANDARD kvm_restore_fpu
On 2025/12/22 下午7:34, Xianglai Li wrote:
If we directly compile the switch.S file into the kernel, the address of the kvm_exc_entry function will definitely be within the DMW memory area. Therefore, we will no longer need to perform a copy relocation of kvm_exc_entry.
Based on the above description, compile switch.S directly into the kernel, and then remove the copy relocation execution logic for the kvm_exc_entry function.
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/Kbuild | 2 +- arch/loongarch/include/asm/asm-prototypes.h | 21 +++++++++++++ arch/loongarch/include/asm/kvm_host.h | 3 -- arch/loongarch/kvm/Makefile | 2 +- arch/loongarch/kvm/main.c | 35 ++------------------- arch/loongarch/kvm/switch.S | 22 ++++++++++--- 6 files changed, 43 insertions(+), 42 deletions(-)
diff --git a/arch/loongarch/Kbuild b/arch/loongarch/Kbuild index beb8499dd8ed..1c7a0dbe5e72 100644 --- a/arch/loongarch/Kbuild +++ b/arch/loongarch/Kbuild @@ -3,7 +3,7 @@ obj-y += mm/ obj-y += net/ obj-y += vdso/ -obj-$(CONFIG_KVM) += kvm/ +obj-$(subst m,y,$(CONFIG_KVM)) += kvm/ # for cleaning subdir- += boot diff --git a/arch/loongarch/include/asm/asm-prototypes.h b/arch/loongarch/include/asm/asm-prototypes.h index 704066b4f736..e8ce153691e5 100644 --- a/arch/loongarch/include/asm/asm-prototypes.h +++ b/arch/loongarch/include/asm/asm-prototypes.h @@ -20,3 +20,24 @@ asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_ struct pt_regs *regs, int (*fn)(void *), void *fn_arg);
+struct kvm_run; +struct kvm_vcpu;
+void kvm_exc_entry(void); +int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu);
+struct loongarch_fpu;
+#ifdef CONFIG_CPU_HAS_LSX +void kvm_save_lsx(struct loongarch_fpu *fpu); +void kvm_restore_lsx(struct loongarch_fpu *fpu); +#endif
+#ifdef CONFIG_CPU_HAS_LASX +void kvm_save_lasx(struct loongarch_fpu *fpu); +void kvm_restore_lasx(struct loongarch_fpu *fpu); +#endif
+void kvm_save_fpu(struct loongarch_fpu *fpu); +void kvm_restore_fpu(struct loongarch_fpu *fpu); diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h index e4fe5b8e8149..1a1be10e3803 100644 --- a/arch/loongarch/include/asm/kvm_host.h +++ b/arch/loongarch/include/asm/kvm_host.h @@ -85,7 +85,6 @@ struct kvm_context { struct kvm_world_switch { int (*exc_entry)(void); int (*enter_guest)(struct kvm_run *run, struct kvm_vcpu *vcpu);
- unsigned long page_order; };
#define MAX_PGTABLE_LEVELS 4 @@ -347,8 +346,6 @@ void kvm_exc_entry(void); int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu); extern unsigned long vpid_mask; -extern const unsigned long kvm_exception_size; -extern const unsigned long kvm_enter_guest_size; extern struct kvm_world_switch *kvm_loongarch_ops; #define SW_GCSR (1 << 0) diff --git a/arch/loongarch/kvm/Makefile b/arch/loongarch/kvm/Makefile index cb41d9265662..fe665054f824 100644 --- a/arch/loongarch/kvm/Makefile +++ b/arch/loongarch/kvm/Makefile @@ -11,7 +11,7 @@ kvm-y += exit.o kvm-y += interrupt.o kvm-y += main.o kvm-y += mmu.o -kvm-y += switch.o +obj-y += switch.o kvm-y += timer.o kvm-y += tlb.o kvm-y += vcpu.o diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c index 80ea63d465b8..67d234540ed4 100644 --- a/arch/loongarch/kvm/main.c +++ b/arch/loongarch/kvm/main.c @@ -340,8 +340,7 @@ void kvm_arch_disable_virtualization_cpu(void) static int kvm_loongarch_env_init(void) {
- int cpu, order, ret;
- void *addr;
- int cpu, ret; struct kvm_context *context;
vmcs = alloc_percpu(struct kvm_context); @@ -357,30 +356,8 @@ static int kvm_loongarch_env_init(void) return -ENOMEM; }
- /*
* PGD register is shared between root kernel and kvm hypervisor.* So world switch entry should be in DMW area rather than TLB area* to avoid page fault reenter.** In future if hardware pagetable walking is supported, we won't* need to copy world switch code to DMW area.*/- order = get_order(kvm_exception_size + kvm_enter_guest_size);
- addr = (void *)__get_free_pages(GFP_KERNEL, order);
- if (!addr) {
free_percpu(vmcs);vmcs = NULL;kfree(kvm_loongarch_ops);kvm_loongarch_ops = NULL;return -ENOMEM;- }
- memcpy(addr, kvm_exc_entry, kvm_exception_size);
- memcpy(addr + kvm_exception_size, kvm_enter_guest, kvm_enter_guest_size);
- flush_icache_range((unsigned long)addr, (unsigned long)addr + kvm_exception_size + kvm_enter_guest_size);
- kvm_loongarch_ops->exc_entry = addr;
- kvm_loongarch_ops->enter_guest = addr + kvm_exception_size;
- kvm_loongarch_ops->page_order = order;
- kvm_loongarch_ops->exc_entry = (void *)kvm_exc_entry;
- kvm_loongarch_ops->enter_guest = (void *)kvm_enter_guest;
vpid_mask = read_csr_gstat(); vpid_mask = (vpid_mask & CSR_GSTAT_GIDBIT) >> CSR_GSTAT_GIDBIT_SHIFT; @@ -414,16 +391,10 @@ static int kvm_loongarch_env_init(void) static void kvm_loongarch_env_exit(void) {
- unsigned long addr;
- if (vmcs) free_percpu(vmcs);
if (kvm_loongarch_ops) {
if (kvm_loongarch_ops->exc_entry) {addr = (unsigned long)kvm_loongarch_ops->exc_entry;free_pages(addr, kvm_loongarch_ops->page_order);}diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index f1768b7a6194..93845ce53651 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -5,6 +5,7 @@ #include <linux/linkage.h> #include <asm/asm.h> +#include <asm/page.h> #include <asm/asmmacro.h> #include <asm/loongarch.h> #include <asm/regdef.h> @@ -100,10 +101,18 @@ * - is still in guest mode, such as pgd table/vmid registers etc, * - will fix with hw page walk enabled in future * load kvm_vcpu from reserved CSR KVM_VCPU_KS, and save a2 to KVM_TEMP_KS
** PGD register is shared between root kernel and kvm hypervisor.* So world switch entry should be in DMW area rather than TLB area* to avoid page fault reenter.** In future if hardware pagetable walking is supported, we won't* need to copy world switch code to DMW area.- .p2align PAGE_SHIFT UNWIND_HINT_UNDEFINED csrwr a2, KVM_TEMP_KS csrrd a2, KVM_VCPU_KS
@@ -190,8 +199,8 @@ ret_to_host: kvm_restore_host_gpr a2 jr ra -SYM_INNER_LABEL(kvm_exc_entry_end, SYM_L_LOCAL) SYM_CODE_END(kvm_exc_entry) +EXPORT_SYMBOL(kvm_exc_entry) /*
- int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu)
@@ -215,8 +224,8 @@ SYM_FUNC_START(kvm_enter_guest) /* Save kvm_vcpu to kscratch */ csrwr a1, KVM_VCPU_KS kvm_switch_to_guest -SYM_INNER_LABEL(kvm_enter_guest_end, SYM_L_LOCAL) SYM_FUNC_END(kvm_enter_guest) +EXPORT_SYMBOL(kvm_enter_guest) SYM_FUNC_START(kvm_save_fpu) fpu_save_csr a0 t1 @@ -224,6 +233,7 @@ SYM_FUNC_START(kvm_save_fpu) fpu_save_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_save_fpu) +EXPORT_SYMBOL(kvm_save_fpu)
one small nit, could EXPORT_SYMBOL_FOR_KVM() be used here compared with EXPORT_SYMBOL()?
Regards Bibo Mao
SYM_FUNC_START(kvm_restore_fpu) fpu_restore_double a0 t1 @@ -231,6 +241,7 @@ SYM_FUNC_START(kvm_restore_fpu) fpu_restore_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_fpu) +EXPORT_SYMBOL(kvm_restore_fpu) #ifdef CONFIG_CPU_HAS_LSX SYM_FUNC_START(kvm_save_lsx) @@ -239,6 +250,7 @@ SYM_FUNC_START(kvm_save_lsx) lsx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lsx) +EXPORT_SYMBOL(kvm_save_lsx) SYM_FUNC_START(kvm_restore_lsx) lsx_restore_data a0 t1 @@ -246,6 +258,7 @@ SYM_FUNC_START(kvm_restore_lsx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lsx) +EXPORT_SYMBOL(kvm_restore_lsx) #endif #ifdef CONFIG_CPU_HAS_LASX @@ -255,6 +268,7 @@ SYM_FUNC_START(kvm_save_lasx) lasx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lasx) +EXPORT_SYMBOL(kvm_save_lasx) SYM_FUNC_START(kvm_restore_lasx) lasx_restore_data a0 t1 @@ -262,10 +276,8 @@ SYM_FUNC_START(kvm_restore_lasx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lasx) +EXPORT_SYMBOL(kvm_restore_lasx) #endif
- .section ".rodata"
-SYM_DATA(kvm_exception_size, .quad kvm_exc_entry_end - kvm_exc_entry) -SYM_DATA(kvm_enter_guest_size, .quad kvm_enter_guest_end - kvm_enter_guest) #ifdef CONFIG_CPU_HAS_LBT STACK_FRAME_NON_STANDARD kvm_restore_fpu
Hi Bibo Mao:
On 2025/12/22 下午7:34, Xianglai Li wrote:
If we directly compile the switch.S file into the kernel, the address of the kvm_exc_entry function will definitely be within the DMW memory area. Therefore, we will no longer need to perform a copy relocation of kvm_exc_entry.
Based on the above description, compile switch.S directly into the kernel, and then remove the copy relocation execution logic for the kvm_exc_entry function.
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/Kbuild | 2 +- arch/loongarch/include/asm/asm-prototypes.h | 21 +++++++++++++ arch/loongarch/include/asm/kvm_host.h | 3 -- arch/loongarch/kvm/Makefile | 2 +- arch/loongarch/kvm/main.c | 35 ++------------------- arch/loongarch/kvm/switch.S | 22 ++++++++++--- 6 files changed, 43 insertions(+), 42 deletions(-)
diff --git a/arch/loongarch/Kbuild b/arch/loongarch/Kbuild index beb8499dd8ed..1c7a0dbe5e72 100644 --- a/arch/loongarch/Kbuild +++ b/arch/loongarch/Kbuild @@ -3,7 +3,7 @@ obj-y += mm/ obj-y += net/ obj-y += vdso/ -obj-$(CONFIG_KVM) += kvm/ +obj-$(subst m,y,$(CONFIG_KVM)) += kvm/ # for cleaning subdir- += boot diff --git a/arch/loongarch/include/asm/asm-prototypes.h b/arch/loongarch/include/asm/asm-prototypes.h index 704066b4f736..e8ce153691e5 100644 --- a/arch/loongarch/include/asm/asm-prototypes.h +++ b/arch/loongarch/include/asm/asm-prototypes.h @@ -20,3 +20,24 @@ asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_ struct pt_regs *regs, int (*fn)(void *), void *fn_arg);
+struct kvm_run; +struct kvm_vcpu;
+void kvm_exc_entry(void); +int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu);
+struct loongarch_fpu;
+#ifdef CONFIG_CPU_HAS_LSX +void kvm_save_lsx(struct loongarch_fpu *fpu); +void kvm_restore_lsx(struct loongarch_fpu *fpu); +#endif
+#ifdef CONFIG_CPU_HAS_LASX +void kvm_save_lasx(struct loongarch_fpu *fpu); +void kvm_restore_lasx(struct loongarch_fpu *fpu); +#endif
+void kvm_save_fpu(struct loongarch_fpu *fpu); +void kvm_restore_fpu(struct loongarch_fpu *fpu); diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h index e4fe5b8e8149..1a1be10e3803 100644 --- a/arch/loongarch/include/asm/kvm_host.h +++ b/arch/loongarch/include/asm/kvm_host.h @@ -85,7 +85,6 @@ struct kvm_context { struct kvm_world_switch { int (*exc_entry)(void); int (*enter_guest)(struct kvm_run *run, struct kvm_vcpu *vcpu); - unsigned long page_order; }; #define MAX_PGTABLE_LEVELS 4 @@ -347,8 +346,6 @@ void kvm_exc_entry(void); int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu); extern unsigned long vpid_mask; -extern const unsigned long kvm_exception_size; -extern const unsigned long kvm_enter_guest_size; extern struct kvm_world_switch *kvm_loongarch_ops; #define SW_GCSR (1 << 0) diff --git a/arch/loongarch/kvm/Makefile b/arch/loongarch/kvm/Makefile index cb41d9265662..fe665054f824 100644 --- a/arch/loongarch/kvm/Makefile +++ b/arch/loongarch/kvm/Makefile @@ -11,7 +11,7 @@ kvm-y += exit.o kvm-y += interrupt.o kvm-y += main.o kvm-y += mmu.o -kvm-y += switch.o +obj-y += switch.o kvm-y += timer.o kvm-y += tlb.o kvm-y += vcpu.o diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c index 80ea63d465b8..67d234540ed4 100644 --- a/arch/loongarch/kvm/main.c +++ b/arch/loongarch/kvm/main.c @@ -340,8 +340,7 @@ void kvm_arch_disable_virtualization_cpu(void) static int kvm_loongarch_env_init(void) { - int cpu, order, ret; - void *addr; + int cpu, ret; struct kvm_context *context; vmcs = alloc_percpu(struct kvm_context); @@ -357,30 +356,8 @@ static int kvm_loongarch_env_init(void) return -ENOMEM; } - /* - * PGD register is shared between root kernel and kvm hypervisor. - * So world switch entry should be in DMW area rather than TLB area - * to avoid page fault reenter. - * - * In future if hardware pagetable walking is supported, we won't - * need to copy world switch code to DMW area. - */ - order = get_order(kvm_exception_size + kvm_enter_guest_size); - addr = (void *)__get_free_pages(GFP_KERNEL, order); - if (!addr) { - free_percpu(vmcs); - vmcs = NULL; - kfree(kvm_loongarch_ops); - kvm_loongarch_ops = NULL; - return -ENOMEM; - }
- memcpy(addr, kvm_exc_entry, kvm_exception_size); - memcpy(addr + kvm_exception_size, kvm_enter_guest, kvm_enter_guest_size); - flush_icache_range((unsigned long)addr, (unsigned long)addr + kvm_exception_size + kvm_enter_guest_size); - kvm_loongarch_ops->exc_entry = addr; - kvm_loongarch_ops->enter_guest = addr + kvm_exception_size; - kvm_loongarch_ops->page_order = order; + kvm_loongarch_ops->exc_entry = (void *)kvm_exc_entry; + kvm_loongarch_ops->enter_guest = (void *)kvm_enter_guest; vpid_mask = read_csr_gstat(); vpid_mask = (vpid_mask & CSR_GSTAT_GIDBIT) >> CSR_GSTAT_GIDBIT_SHIFT; @@ -414,16 +391,10 @@ static int kvm_loongarch_env_init(void) static void kvm_loongarch_env_exit(void) { - unsigned long addr;
if (vmcs) free_percpu(vmcs); if (kvm_loongarch_ops) { - if (kvm_loongarch_ops->exc_entry) { - addr = (unsigned long)kvm_loongarch_ops->exc_entry; - free_pages(addr, kvm_loongarch_ops->page_order); - } kfree(kvm_loongarch_ops); } diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index f1768b7a6194..93845ce53651 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -5,6 +5,7 @@ #include <linux/linkage.h> #include <asm/asm.h> +#include <asm/page.h> #include <asm/asmmacro.h> #include <asm/loongarch.h> #include <asm/regdef.h> @@ -100,10 +101,18 @@ * - is still in guest mode, such as pgd table/vmid registers etc, * - will fix with hw page walk enabled in future * load kvm_vcpu from reserved CSR KVM_VCPU_KS, and save a2 to KVM_TEMP_KS + * + * PGD register is shared between root kernel and kvm hypervisor. + * So world switch entry should be in DMW area rather than TLB area + * to avoid page fault reenter. + * + * In future if hardware pagetable walking is supported, we won't + * need to copy world switch code to DMW area. */ .text .cfi_sections .debug_frame SYM_CODE_START(kvm_exc_entry) + .p2align PAGE_SHIFT UNWIND_HINT_UNDEFINED csrwr a2, KVM_TEMP_KS csrrd a2, KVM_VCPU_KS @@ -190,8 +199,8 @@ ret_to_host: kvm_restore_host_gpr a2 jr ra -SYM_INNER_LABEL(kvm_exc_entry_end, SYM_L_LOCAL) SYM_CODE_END(kvm_exc_entry) +EXPORT_SYMBOL(kvm_exc_entry) /* * int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu) @@ -215,8 +224,8 @@ SYM_FUNC_START(kvm_enter_guest) /* Save kvm_vcpu to kscratch */ csrwr a1, KVM_VCPU_KS kvm_switch_to_guest -SYM_INNER_LABEL(kvm_enter_guest_end, SYM_L_LOCAL) SYM_FUNC_END(kvm_enter_guest) +EXPORT_SYMBOL(kvm_enter_guest) SYM_FUNC_START(kvm_save_fpu) fpu_save_csr a0 t1 @@ -224,6 +233,7 @@ SYM_FUNC_START(kvm_save_fpu) fpu_save_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_save_fpu) +EXPORT_SYMBOL(kvm_save_fpu)
one small nit, could EXPORT_SYMBOL_FOR_KVM() be used here compared with EXPORT_SYMBOL()?
Ok! will fix it in next version Thanks! Xianglai.
Regards Bibo Mao
SYM_FUNC_START(kvm_restore_fpu) fpu_restore_double a0 t1 @@ -231,6 +241,7 @@ SYM_FUNC_START(kvm_restore_fpu) fpu_restore_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_fpu) +EXPORT_SYMBOL(kvm_restore_fpu) #ifdef CONFIG_CPU_HAS_LSX SYM_FUNC_START(kvm_save_lsx) @@ -239,6 +250,7 @@ SYM_FUNC_START(kvm_save_lsx) lsx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lsx) +EXPORT_SYMBOL(kvm_save_lsx) SYM_FUNC_START(kvm_restore_lsx) lsx_restore_data a0 t1 @@ -246,6 +258,7 @@ SYM_FUNC_START(kvm_restore_lsx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lsx) +EXPORT_SYMBOL(kvm_restore_lsx) #endif #ifdef CONFIG_CPU_HAS_LASX @@ -255,6 +268,7 @@ SYM_FUNC_START(kvm_save_lasx) lasx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lasx) +EXPORT_SYMBOL(kvm_save_lasx) SYM_FUNC_START(kvm_restore_lasx) lasx_restore_data a0 t1 @@ -262,10 +276,8 @@ SYM_FUNC_START(kvm_restore_lasx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lasx) +EXPORT_SYMBOL(kvm_restore_lasx) #endif - .section ".rodata" -SYM_DATA(kvm_exception_size, .quad kvm_exc_entry_end - kvm_exc_entry) -SYM_DATA(kvm_enter_guest_size, .quad kvm_enter_guest_end - kvm_enter_guest) #ifdef CONFIG_CPU_HAS_LBT STACK_FRAME_NON_STANDARD kvm_restore_fpu
Hi, Xianglai,
On Tue, Dec 23, 2025 at 10:38 AM lixianglai lixianglai@loongson.cn wrote:
Hi Bibo Mao:
On 2025/12/22 下午7:34, Xianglai Li wrote:
If we directly compile the switch.S file into the kernel, the address of the kvm_exc_entry function will definitely be within the DMW memory area. Therefore, we will no longer need to perform a copy relocation of kvm_exc_entry.
Based on the above description, compile switch.S directly into the kernel, and then remove the copy relocation execution logic for the kvm_exc_entry function.
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/Kbuild | 2 +- arch/loongarch/include/asm/asm-prototypes.h | 21 +++++++++++++ arch/loongarch/include/asm/kvm_host.h | 3 -- arch/loongarch/kvm/Makefile | 2 +- arch/loongarch/kvm/main.c | 35 ++------------------- arch/loongarch/kvm/switch.S | 22 ++++++++++--- 6 files changed, 43 insertions(+), 42 deletions(-)
diff --git a/arch/loongarch/Kbuild b/arch/loongarch/Kbuild index beb8499dd8ed..1c7a0dbe5e72 100644 --- a/arch/loongarch/Kbuild +++ b/arch/loongarch/Kbuild @@ -3,7 +3,7 @@ obj-y += mm/ obj-y += net/ obj-y += vdso/ -obj-$(CONFIG_KVM) += kvm/ +obj-$(subst m,y,$(CONFIG_KVM)) += kvm/ # for cleaning subdir- += boot diff --git a/arch/loongarch/include/asm/asm-prototypes.h b/arch/loongarch/include/asm/asm-prototypes.h index 704066b4f736..e8ce153691e5 100644 --- a/arch/loongarch/include/asm/asm-prototypes.h +++ b/arch/loongarch/include/asm/asm-prototypes.h @@ -20,3 +20,24 @@ asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_ struct pt_regs *regs, int (*fn)(void *), void *fn_arg);
+struct kvm_run; +struct kvm_vcpu;
+void kvm_exc_entry(void); +int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu);
+struct loongarch_fpu;
+#ifdef CONFIG_CPU_HAS_LSX +void kvm_save_lsx(struct loongarch_fpu *fpu); +void kvm_restore_lsx(struct loongarch_fpu *fpu); +#endif
+#ifdef CONFIG_CPU_HAS_LASX +void kvm_save_lasx(struct loongarch_fpu *fpu); +void kvm_restore_lasx(struct loongarch_fpu *fpu); +#endif
+void kvm_save_fpu(struct loongarch_fpu *fpu); +void kvm_restore_fpu(struct loongarch_fpu *fpu); diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h index e4fe5b8e8149..1a1be10e3803 100644 --- a/arch/loongarch/include/asm/kvm_host.h +++ b/arch/loongarch/include/asm/kvm_host.h @@ -85,7 +85,6 @@ struct kvm_context { struct kvm_world_switch { int (*exc_entry)(void); int (*enter_guest)(struct kvm_run *run, struct kvm_vcpu *vcpu);
- unsigned long page_order; }; #define MAX_PGTABLE_LEVELS 4
@@ -347,8 +346,6 @@ void kvm_exc_entry(void); int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu); extern unsigned long vpid_mask; -extern const unsigned long kvm_exception_size; -extern const unsigned long kvm_enter_guest_size; extern struct kvm_world_switch *kvm_loongarch_ops; #define SW_GCSR (1 << 0) diff --git a/arch/loongarch/kvm/Makefile b/arch/loongarch/kvm/Makefile index cb41d9265662..fe665054f824 100644 --- a/arch/loongarch/kvm/Makefile +++ b/arch/loongarch/kvm/Makefile @@ -11,7 +11,7 @@ kvm-y += exit.o kvm-y += interrupt.o kvm-y += main.o kvm-y += mmu.o -kvm-y += switch.o +obj-y += switch.o kvm-y += timer.o kvm-y += tlb.o kvm-y += vcpu.o diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c index 80ea63d465b8..67d234540ed4 100644 --- a/arch/loongarch/kvm/main.c +++ b/arch/loongarch/kvm/main.c @@ -340,8 +340,7 @@ void kvm_arch_disable_virtualization_cpu(void) static int kvm_loongarch_env_init(void) {
- int cpu, order, ret;
- void *addr;
- int cpu, ret; struct kvm_context *context; vmcs = alloc_percpu(struct kvm_context);
@@ -357,30 +356,8 @@ static int kvm_loongarch_env_init(void) return -ENOMEM; }
- /*
* PGD register is shared between root kernel and kvm hypervisor.* So world switch entry should be in DMW area rather than TLB area* to avoid page fault reenter.** In future if hardware pagetable walking is supported, we won't* need to copy world switch code to DMW area.*/- order = get_order(kvm_exception_size + kvm_enter_guest_size);
- addr = (void *)__get_free_pages(GFP_KERNEL, order);
- if (!addr) {
free_percpu(vmcs);vmcs = NULL;kfree(kvm_loongarch_ops);kvm_loongarch_ops = NULL;return -ENOMEM;- }
- memcpy(addr, kvm_exc_entry, kvm_exception_size);
- memcpy(addr + kvm_exception_size, kvm_enter_guest,
kvm_enter_guest_size);
- flush_icache_range((unsigned long)addr, (unsigned long)addr +
kvm_exception_size + kvm_enter_guest_size);
- kvm_loongarch_ops->exc_entry = addr;
- kvm_loongarch_ops->enter_guest = addr + kvm_exception_size;
- kvm_loongarch_ops->page_order = order;
- kvm_loongarch_ops->exc_entry = (void *)kvm_exc_entry;
- kvm_loongarch_ops->enter_guest = (void *)kvm_enter_guest; vpid_mask = read_csr_gstat(); vpid_mask = (vpid_mask & CSR_GSTAT_GIDBIT) >>
CSR_GSTAT_GIDBIT_SHIFT; @@ -414,16 +391,10 @@ static int kvm_loongarch_env_init(void) static void kvm_loongarch_env_exit(void) {
- unsigned long addr;
if (vmcs) free_percpu(vmcs); if (kvm_loongarch_ops) {if (kvm_loongarch_ops->exc_entry) {addr = (unsigned long)kvm_loongarch_ops->exc_entry;free_pages(addr, kvm_loongarch_ops->page_order);} kfree(kvm_loongarch_ops); }index f1768b7a6194..93845ce53651 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -5,6 +5,7 @@ #include <linux/linkage.h> #include <asm/asm.h> +#include <asm/page.h> #include <asm/asmmacro.h> #include <asm/loongarch.h> #include <asm/regdef.h> @@ -100,10 +101,18 @@ * - is still in guest mode, such as pgd table/vmid registers etc, * - will fix with hw page walk enabled in future * load kvm_vcpu from reserved CSR KVM_VCPU_KS, and save a2 to KVM_TEMP_KS
** PGD register is shared between root kernel and kvm hypervisor.* So world switch entry should be in DMW area rather than TLB area* to avoid page fault reenter.** In future if hardware pagetable walking is supported, we won't* need to copy world switch code to DMW area. */ .text .cfi_sections .debug_frame- .p2align PAGE_SHIFT
I'm not sure, but if this line can be moved after .text, it seems better.
Huacai
UNWIND_HINT_UNDEFINED csrwr a2, KVM_TEMP_KS csrrd a2, KVM_VCPU_KS@@ -190,8 +199,8 @@ ret_to_host: kvm_restore_host_gpr a2 jr ra -SYM_INNER_LABEL(kvm_exc_entry_end, SYM_L_LOCAL) SYM_CODE_END(kvm_exc_entry) +EXPORT_SYMBOL(kvm_exc_entry) /*
- int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu)
@@ -215,8 +224,8 @@ SYM_FUNC_START(kvm_enter_guest) /* Save kvm_vcpu to kscratch */ csrwr a1, KVM_VCPU_KS kvm_switch_to_guest -SYM_INNER_LABEL(kvm_enter_guest_end, SYM_L_LOCAL) SYM_FUNC_END(kvm_enter_guest) +EXPORT_SYMBOL(kvm_enter_guest) SYM_FUNC_START(kvm_save_fpu) fpu_save_csr a0 t1 @@ -224,6 +233,7 @@ SYM_FUNC_START(kvm_save_fpu) fpu_save_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_save_fpu) +EXPORT_SYMBOL(kvm_save_fpu)
one small nit, could EXPORT_SYMBOL_FOR_KVM() be used here compared with EXPORT_SYMBOL()?
Ok! will fix it in next version Thanks! Xianglai.
Regards Bibo Mao
SYM_FUNC_START(kvm_restore_fpu) fpu_restore_double a0 t1@@ -231,6 +241,7 @@ SYM_FUNC_START(kvm_restore_fpu) fpu_restore_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_fpu) +EXPORT_SYMBOL(kvm_restore_fpu) #ifdef CONFIG_CPU_HAS_LSX SYM_FUNC_START(kvm_save_lsx) @@ -239,6 +250,7 @@ SYM_FUNC_START(kvm_save_lsx) lsx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lsx) +EXPORT_SYMBOL(kvm_save_lsx) SYM_FUNC_START(kvm_restore_lsx) lsx_restore_data a0 t1 @@ -246,6 +258,7 @@ SYM_FUNC_START(kvm_restore_lsx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lsx) +EXPORT_SYMBOL(kvm_restore_lsx) #endif #ifdef CONFIG_CPU_HAS_LASX @@ -255,6 +268,7 @@ SYM_FUNC_START(kvm_save_lasx) lasx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lasx) +EXPORT_SYMBOL(kvm_save_lasx) SYM_FUNC_START(kvm_restore_lasx) lasx_restore_data a0 t1 @@ -262,10 +276,8 @@ SYM_FUNC_START(kvm_restore_lasx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lasx) +EXPORT_SYMBOL(kvm_restore_lasx) #endif
- .section ".rodata"
-SYM_DATA(kvm_exception_size, .quad kvm_exc_entry_end - kvm_exc_entry) -SYM_DATA(kvm_enter_guest_size, .quad kvm_enter_guest_end - kvm_enter_guest) #ifdef CONFIG_CPU_HAS_LBT STACK_FRAME_NON_STANDARD kvm_restore_fpu
Hi Huacai Chen:
Hi, Xianglai,
On Tue, Dec 23, 2025 at 10:38 AM lixianglai lixianglai@loongson.cn wrote:
Hi Bibo Mao:
On 2025/12/22 下午7:34, Xianglai Li wrote:
If we directly compile the switch.S file into the kernel, the address of the kvm_exc_entry function will definitely be within the DMW memory area. Therefore, we will no longer need to perform a copy relocation of kvm_exc_entry.
Based on the above description, compile switch.S directly into the kernel, and then remove the copy relocation execution logic for the kvm_exc_entry function.
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/Kbuild | 2 +- arch/loongarch/include/asm/asm-prototypes.h | 21 +++++++++++++ arch/loongarch/include/asm/kvm_host.h | 3 -- arch/loongarch/kvm/Makefile | 2 +- arch/loongarch/kvm/main.c | 35 ++------------------- arch/loongarch/kvm/switch.S | 22 ++++++++++--- 6 files changed, 43 insertions(+), 42 deletions(-)
diff --git a/arch/loongarch/Kbuild b/arch/loongarch/Kbuild index beb8499dd8ed..1c7a0dbe5e72 100644 --- a/arch/loongarch/Kbuild +++ b/arch/loongarch/Kbuild @@ -3,7 +3,7 @@ obj-y += mm/ obj-y += net/ obj-y += vdso/ -obj-$(CONFIG_KVM) += kvm/ +obj-$(subst m,y,$(CONFIG_KVM)) += kvm/ # for cleaning subdir- += boot diff --git a/arch/loongarch/include/asm/asm-prototypes.h b/arch/loongarch/include/asm/asm-prototypes.h index 704066b4f736..e8ce153691e5 100644 --- a/arch/loongarch/include/asm/asm-prototypes.h +++ b/arch/loongarch/include/asm/asm-prototypes.h @@ -20,3 +20,24 @@ asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_ struct pt_regs *regs, int (*fn)(void *), void *fn_arg);
+struct kvm_run; +struct kvm_vcpu;
+void kvm_exc_entry(void); +int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu);
+struct loongarch_fpu;
+#ifdef CONFIG_CPU_HAS_LSX +void kvm_save_lsx(struct loongarch_fpu *fpu); +void kvm_restore_lsx(struct loongarch_fpu *fpu); +#endif
+#ifdef CONFIG_CPU_HAS_LASX +void kvm_save_lasx(struct loongarch_fpu *fpu); +void kvm_restore_lasx(struct loongarch_fpu *fpu); +#endif
+void kvm_save_fpu(struct loongarch_fpu *fpu); +void kvm_restore_fpu(struct loongarch_fpu *fpu); diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h index e4fe5b8e8149..1a1be10e3803 100644 --- a/arch/loongarch/include/asm/kvm_host.h +++ b/arch/loongarch/include/asm/kvm_host.h @@ -85,7 +85,6 @@ struct kvm_context { struct kvm_world_switch { int (*exc_entry)(void); int (*enter_guest)(struct kvm_run *run, struct kvm_vcpu *vcpu);
- unsigned long page_order; }; #define MAX_PGTABLE_LEVELS 4
@@ -347,8 +346,6 @@ void kvm_exc_entry(void); int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu); extern unsigned long vpid_mask; -extern const unsigned long kvm_exception_size; -extern const unsigned long kvm_enter_guest_size; extern struct kvm_world_switch *kvm_loongarch_ops; #define SW_GCSR (1 << 0) diff --git a/arch/loongarch/kvm/Makefile b/arch/loongarch/kvm/Makefile index cb41d9265662..fe665054f824 100644 --- a/arch/loongarch/kvm/Makefile +++ b/arch/loongarch/kvm/Makefile @@ -11,7 +11,7 @@ kvm-y += exit.o kvm-y += interrupt.o kvm-y += main.o kvm-y += mmu.o -kvm-y += switch.o +obj-y += switch.o kvm-y += timer.o kvm-y += tlb.o kvm-y += vcpu.o diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c index 80ea63d465b8..67d234540ed4 100644 --- a/arch/loongarch/kvm/main.c +++ b/arch/loongarch/kvm/main.c @@ -340,8 +340,7 @@ void kvm_arch_disable_virtualization_cpu(void) static int kvm_loongarch_env_init(void) {
- int cpu, order, ret;
- void *addr;
- int cpu, ret; struct kvm_context *context; vmcs = alloc_percpu(struct kvm_context);
@@ -357,30 +356,8 @@ static int kvm_loongarch_env_init(void) return -ENOMEM; }
- /*
* PGD register is shared between root kernel and kvm hypervisor.* So world switch entry should be in DMW area rather than TLB area* to avoid page fault reenter.** In future if hardware pagetable walking is supported, we won't* need to copy world switch code to DMW area.*/- order = get_order(kvm_exception_size + kvm_enter_guest_size);
- addr = (void *)__get_free_pages(GFP_KERNEL, order);
- if (!addr) {
free_percpu(vmcs);vmcs = NULL;kfree(kvm_loongarch_ops);kvm_loongarch_ops = NULL;return -ENOMEM;- }
- memcpy(addr, kvm_exc_entry, kvm_exception_size);
- memcpy(addr + kvm_exception_size, kvm_enter_guest,
kvm_enter_guest_size);
- flush_icache_range((unsigned long)addr, (unsigned long)addr +
kvm_exception_size + kvm_enter_guest_size);
- kvm_loongarch_ops->exc_entry = addr;
- kvm_loongarch_ops->enter_guest = addr + kvm_exception_size;
- kvm_loongarch_ops->page_order = order;
- kvm_loongarch_ops->exc_entry = (void *)kvm_exc_entry;
- kvm_loongarch_ops->enter_guest = (void *)kvm_enter_guest; vpid_mask = read_csr_gstat(); vpid_mask = (vpid_mask & CSR_GSTAT_GIDBIT) >>
CSR_GSTAT_GIDBIT_SHIFT; @@ -414,16 +391,10 @@ static int kvm_loongarch_env_init(void) static void kvm_loongarch_env_exit(void) {
- unsigned long addr;
if (vmcs) free_percpu(vmcs); if (kvm_loongarch_ops) {if (kvm_loongarch_ops->exc_entry) {addr = (unsigned long)kvm_loongarch_ops->exc_entry;free_pages(addr, kvm_loongarch_ops->page_order);} kfree(kvm_loongarch_ops); }index f1768b7a6194..93845ce53651 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -5,6 +5,7 @@ #include <linux/linkage.h> #include <asm/asm.h> +#include <asm/page.h> #include <asm/asmmacro.h> #include <asm/loongarch.h> #include <asm/regdef.h> @@ -100,10 +101,18 @@ * - is still in guest mode, such as pgd table/vmid registers etc, * - will fix with hw page walk enabled in future * load kvm_vcpu from reserved CSR KVM_VCPU_KS, and save a2 to KVM_TEMP_KS
** PGD register is shared between root kernel and kvm hypervisor.* So world switch entry should be in DMW area rather than TLB area* to avoid page fault reenter.** In future if hardware pagetable walking is supported, we won't* need to copy world switch code to DMW area. */ .text .cfi_sections .debug_frame- .p2align PAGE_SHIFT
I'm not sure, but if this line can be moved after .text, it seems better.
I will try and test it as suggested, and if it works, I will fix it
Thanks! Xianglai.
Huacai
UNWIND_HINT_UNDEFINED csrwr a2, KVM_TEMP_KS csrrd a2, KVM_VCPU_KS@@ -190,8 +199,8 @@ ret_to_host: kvm_restore_host_gpr a2 jr ra -SYM_INNER_LABEL(kvm_exc_entry_end, SYM_L_LOCAL) SYM_CODE_END(kvm_exc_entry) +EXPORT_SYMBOL(kvm_exc_entry) /* * int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu) @@ -215,8 +224,8 @@ SYM_FUNC_START(kvm_enter_guest) /* Save kvm_vcpu to kscratch */ csrwr a1, KVM_VCPU_KS kvm_switch_to_guest -SYM_INNER_LABEL(kvm_enter_guest_end, SYM_L_LOCAL) SYM_FUNC_END(kvm_enter_guest) +EXPORT_SYMBOL(kvm_enter_guest) SYM_FUNC_START(kvm_save_fpu) fpu_save_csr a0 t1 @@ -224,6 +233,7 @@ SYM_FUNC_START(kvm_save_fpu) fpu_save_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_save_fpu) +EXPORT_SYMBOL(kvm_save_fpu)
one small nit, could EXPORT_SYMBOL_FOR_KVM() be used here compared with EXPORT_SYMBOL()?
Ok! will fix it in next version Thanks! Xianglai.
Regards Bibo Mao
SYM_FUNC_START(kvm_restore_fpu) fpu_restore_double a0 t1@@ -231,6 +241,7 @@ SYM_FUNC_START(kvm_restore_fpu) fpu_restore_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_fpu) +EXPORT_SYMBOL(kvm_restore_fpu) #ifdef CONFIG_CPU_HAS_LSX SYM_FUNC_START(kvm_save_lsx) @@ -239,6 +250,7 @@ SYM_FUNC_START(kvm_save_lsx) lsx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lsx) +EXPORT_SYMBOL(kvm_save_lsx) SYM_FUNC_START(kvm_restore_lsx) lsx_restore_data a0 t1 @@ -246,6 +258,7 @@ SYM_FUNC_START(kvm_restore_lsx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lsx) +EXPORT_SYMBOL(kvm_restore_lsx) #endif #ifdef CONFIG_CPU_HAS_LASX @@ -255,6 +268,7 @@ SYM_FUNC_START(kvm_save_lasx) lasx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lasx) +EXPORT_SYMBOL(kvm_save_lasx) SYM_FUNC_START(kvm_restore_lasx) lasx_restore_data a0 t1 @@ -262,10 +276,8 @@ SYM_FUNC_START(kvm_restore_lasx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lasx) +EXPORT_SYMBOL(kvm_restore_lasx) #endif
- .section ".rodata"
-SYM_DATA(kvm_exception_size, .quad kvm_exc_entry_end - kvm_exc_entry) -SYM_DATA(kvm_enter_guest_size, .quad kvm_enter_guest_end - kvm_enter_guest) #ifdef CONFIG_CPU_HAS_LBT STACK_FRAME_NON_STANDARD kvm_restore_fpu
Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines.
While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information
Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0
Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x94/0x190 [<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn --- Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/kvm/switch.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..e3ecb24a3bc5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -170,6 +170,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE + UNWIND_HINT_REGS
/* Prepare handle exception */ or a0, s0, zero @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2 + st.d ra, a2, PT_ERA
addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP
On 2025/12/22 下午7:34, Xianglai Li wrote:
Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines.
While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information
Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0
Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x94/0x190 [<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/kvm/switch.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..e3ecb24a3bc5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -170,6 +170,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE
- UNWIND_HINT_REGS
/* Prepare handle exception */ or a0, s0, zero @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2
- st.d ra, a2, PT_ERA
Had better add some comments here to show that it is special for unwind usage since there is "st.d ra, a2, PT_R1" already in macro kvm_save_host_gpr().
Regards Bibo Mao
addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP
Hi Bibo Mao:
On 2025/12/22 下午7:34, Xianglai Li wrote:
Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines.
While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information
Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0
Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x94/0x190 [<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/kvm/switch.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..e3ecb24a3bc5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -170,6 +170,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE + UNWIND_HINT_REGS /* Prepare handle exception */ or a0, s0, zero @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2 + st.d ra, a2, PT_ERA
Had better add some comments here to show that it is special for unwind usage since there is "st.d ra, a2, PT_R1" already in macro kvm_save_host_gpr().
Ok, I will add some comments to explain it in the next version. Thanks! Xianglai.
Regards Bibo Mao
addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP
On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao maobibo@loongson.cn wrote:
On 2025/12/22 下午7:34, Xianglai Li wrote:
Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines.
While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information
Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0
Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x94/0x190 [<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/kvm/switch.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..e3ecb24a3bc5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -170,6 +170,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE
UNWIND_HINT_REGS /* Prepare handle exception */ or a0, s0, zero@@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2
st.d ra, a2, PT_ERAHad better add some comments here to show that it is special for unwind usage since there is "st.d ra, a2, PT_R1" already in macro kvm_save_host_gpr().
Then there is a new problem, why can unwinder not recognize the instruction in kvm_save_host_gpr()?
Huacai
Regards Bibo Mao
addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP
On 2025/12/23 上午10:46, Huacai Chen wrote:
On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao maobibo@loongson.cn wrote:
On 2025/12/22 下午7:34, Xianglai Li wrote:
Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines.
While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information
Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0
Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x94/0x190 [<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/kvm/switch.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..e3ecb24a3bc5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -170,6 +170,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE
UNWIND_HINT_REGS /* Prepare handle exception */ or a0, s0, zero@@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2
st.d ra, a2, PT_ERAHad better add some comments here to show that it is special for unwind usage since there is "st.d ra, a2, PT_R1" already in macro kvm_save_host_gpr().
Then there is a new problem, why can unwinder not recognize the instruction in kvm_save_host_gpr()?
maybe it need unwinder owner to answer this question.
Huacai
Regards Bibo Mao
addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP
Add yangtiezhu@loongson.cn
Hi :
On 2025/12/23 上午10:46, Huacai Chen wrote:
On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao maobibo@loongson.cn wrote:
On 2025/12/22 下午7:34, Xianglai Li wrote:
Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines.
While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information
Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0
Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x94/0x190 [<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/kvm/switch.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..e3ecb24a3bc5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -170,6 +170,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE + UNWIND_HINT_REGS
/* Prepare handle exception */ or a0, s0, zero @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2 + st.d ra, a2, PT_ERA
Had better add some comments here to show that it is special for unwind usage since there is "st.d ra, a2, PT_R1" already in macro kvm_save_host_gpr().
Then there is a new problem, why can unwinder not recognize the instruction in kvm_save_host_gpr()?
maybe it need unwinder owner to answer this question.
kvm_save_host_gpr() is an assembler macro that has already been executed and is no longer normal on the stack. Am I explaining correctly? @tiezhu
I guess you might be wondering why unwinder didn't recognize kvm_enter_guest().
There's something wrong with the logic that we're implementing here that we should put the current pc in era instead of ra. This will allow unwind to identify the symbol kvm_enter_guest.
So I will fix it in the next version like this:
@@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2
+ /* + * The csr_era member variable of the pt_regs structure is required + * for unwinding orc to perform stack traceback, so we need to put + * pc into csr_era member variable here. + */ + pcaddi t0, 0 + st.d t0, a2, PT_ERA +
Thanks, Xianglai.
Huacai
Regards Bibo Mao
addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP
Hi:
Add yangtiezhu@loongson.cn
Hi :
On 2025/12/23 上午10:46, Huacai Chen wrote:
On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao maobibo@loongson.cn wrote:
On 2025/12/22 下午7:34, Xianglai Li wrote:
Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines.
While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information
Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0
Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x94/0x190 [<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org Signed-off-by: Xianglai Li lixianglai@loongson.cn
Cc: Huacai Chen chenhuacai@kernel.org Cc: WANG Xuerui kernel@xen0n.name Cc: Tianrui Zhao zhaotianrui@loongson.cn Cc: Bibo Mao maobibo@loongson.cn Cc: Charlie Jenkins charlie@rivosinc.com Cc: Xianglai Li lixianglai@loongson.cn Cc: Thomas Gleixner tglx@linutronix.de
arch/loongarch/kvm/switch.S | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..e3ecb24a3bc5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -170,6 +170,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE + UNWIND_HINT_REGS
/* Prepare handle exception */ or a0, s0, zero @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2 + st.d ra, a2, PT_ERA
Had better add some comments here to show that it is special for unwind usage since there is "st.d ra, a2, PT_R1" already in macro kvm_save_host_gpr().
Then there is a new problem, why can unwinder not recognize the instruction in kvm_save_host_gpr()?
maybe it need unwinder owner to answer this question.
kvm_save_host_gpr() is an assembler macro that has already been executed and is no longer normal on the stack. Am I explaining correctly? @tiezhu
I guess you might be wondering why unwinder didn't recognize kvm_enter_guest().
There's something wrong with the logic that we're implementing here that we should put the current pc in era instead of ra. This will allow unwind to identify the symbol kvm_enter_guest.
So I will fix it in the next version like this:
@@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* Save host GPRs */ kvm_save_host_gpr a2
+ /* + * The csr_era member variable of the pt_regs structure is required + * for unwinding orc to perform stack traceback, so we need to put + * pc into csr_era member variable here. + */ + pcaddi t0, 0 + st.d t0, a2, PT_ERA
We discussed it with @tiezhu internally and he was OK with the change!
Thanks, Xianglai.
Thanks, Xianglai.
Huacai
Regards Bibo Mao
addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP
linux-stable-mirror@lists.linaro.org
-
Bibo Mao -
Huacai Chen -
lixianglai -
Xianglai Li