commit 55e3748e8902ff641e334226bdcb432f9a5d78d3 upstream.
In order to offer ARCH_WORKAROUND_2 support to guests, we need a bit of infrastructure.
Let's add a flag indicating whether or not the guest uses SSBD mitigation. Depending on the state of this flag, allow KVM to disable ARCH_WORKAROUND_2 before entering the guest, and enable it when exiting it.
Reviewed-by: Christoffer Dall christoffer.dall@arm.com Reviewed-by: Mark Rutland mark.rutland@arm.com Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com --- arch/arm/include/asm/kvm_mmu.h | 5 ++++ arch/arm64/include/asm/kvm_asm.h | 3 +++ arch/arm64/include/asm/kvm_host.h | 3 +++ arch/arm64/include/asm/kvm_mmu.h | 24 ++++++++++++++++++ arch/arm64/kvm/hyp/switch.c | 42 +++++++++++++++++++++++++++++++ virt/kvm/arm/arm.c | 4 +++ 6 files changed, 81 insertions(+)
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h index f675162663f0..d2eb24eccf8f 100644 --- a/arch/arm/include/asm/kvm_mmu.h +++ b/arch/arm/include/asm/kvm_mmu.h @@ -335,6 +335,11 @@ static inline int kvm_map_vectors(void) return 0; }
+static inline int hyp_map_aux_data(void) +{ + return 0; +} + #define kvm_phys_to_vttbr(addr) (addr)
#endif /* !__ASSEMBLY__ */ diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index fefd8cf42c35..d4fbb1356c4c 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -33,6 +33,9 @@ #define KVM_ARM64_DEBUG_DIRTY_SHIFT 0 #define KVM_ARM64_DEBUG_DIRTY (1 << KVM_ARM64_DEBUG_DIRTY_SHIFT)
+#define VCPU_WORKAROUND_2_FLAG_SHIFT 0 +#define VCPU_WORKAROUND_2_FLAG (_AC(1, UL) << VCPU_WORKAROUND_2_FLAG_SHIFT) + /* Translate a kernel address of @sym into its equivalent linear mapping */ #define kvm_ksym_ref(sym) \ ({ \ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 469de8acd06f..9bef3f69bdcd 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -216,6 +216,9 @@ struct kvm_vcpu_arch { /* Exception Information */ struct kvm_vcpu_fault_info fault;
+ /* State of various workarounds, see kvm_asm.h for bit assignment */ + u64 workaround_flags; + /* Guest debug state */ u64 debug_flags;
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 6128992c2ded..e3b2ad7dd40a 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -473,6 +473,30 @@ static inline int kvm_map_vectors(void) } #endif
+#ifdef CONFIG_ARM64_SSBD +DECLARE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required); + +static inline int hyp_map_aux_data(void) +{ + int cpu, err; + + for_each_possible_cpu(cpu) { + u64 *ptr; + + ptr = per_cpu_ptr(&arm64_ssbd_callback_required, cpu); + err = create_hyp_mappings(ptr, ptr + 1, PAGE_HYP); + if (err) + return err; + } + return 0; +} +#else +static inline int hyp_map_aux_data(void) +{ + return 0; +} +#endif + #define kvm_phys_to_vttbr(addr) phys_to_ttbr(addr)
#endif /* __ASSEMBLY__ */ diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index d9645236e474..c50cedc447f1 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -15,6 +15,7 @@ * along with this program. If not, see http://www.gnu.org/licenses/. */
+#include <linux/arm-smccc.h> #include <linux/types.h> #include <linux/jump_label.h> #include <uapi/linux/psci.h> @@ -389,6 +390,39 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) return false; }
+static inline bool __hyp_text __needs_ssbd_off(struct kvm_vcpu *vcpu) +{ + if (!cpus_have_const_cap(ARM64_SSBD)) + return false; + + return !(vcpu->arch.workaround_flags & VCPU_WORKAROUND_2_FLAG); +} + +static void __hyp_text __set_guest_arch_workaround_state(struct kvm_vcpu *vcpu) +{ +#ifdef CONFIG_ARM64_SSBD + /* + * The host runs with the workaround always present. If the + * guest wants it disabled, so be it... + */ + if (__needs_ssbd_off(vcpu) && + __hyp_this_cpu_read(arm64_ssbd_callback_required)) + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 0, NULL); +#endif +} + +static void __hyp_text __set_host_arch_workaround_state(struct kvm_vcpu *vcpu) +{ +#ifdef CONFIG_ARM64_SSBD + /* + * If the guest has disabled the workaround, bring it back on. + */ + if (__needs_ssbd_off(vcpu) && + __hyp_this_cpu_read(arm64_ssbd_callback_required)) + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 1, NULL); +#endif +} + /* Switch to the guest for VHE systems running in EL2 */ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu) { @@ -409,6 +443,8 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu) sysreg_restore_guest_state_vhe(guest_ctxt); __debug_switch_to_guest(vcpu);
+ __set_guest_arch_workaround_state(vcpu); + do { /* Jump in the fire! */ exit_code = __guest_enter(vcpu, host_ctxt); @@ -416,6 +452,8 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu) /* And we're baaack! */ } while (fixup_guest_exit(vcpu, &exit_code));
+ __set_host_arch_workaround_state(vcpu); + fp_enabled = fpsimd_enabled_vhe();
sysreg_save_guest_state_vhe(guest_ctxt); @@ -465,6 +503,8 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu) __sysreg_restore_state_nvhe(guest_ctxt); __debug_switch_to_guest(vcpu);
+ __set_guest_arch_workaround_state(vcpu); + do { /* Jump in the fire! */ exit_code = __guest_enter(vcpu, host_ctxt); @@ -472,6 +512,8 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu) /* And we're baaack! */ } while (fixup_guest_exit(vcpu, &exit_code));
+ __set_host_arch_workaround_state(vcpu); + fp_enabled = __fpsimd_enabled_nvhe();
__sysreg_save_state_nvhe(guest_ctxt); diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index a4c1b76240df..2d9b4795edb2 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -1490,6 +1490,10 @@ static int init_hyp_mode(void) } }
+ err = hyp_map_aux_data(); + if (err) + kvm_err("Cannot map host auxilary data: %d\n", err); + return 0;
out_err: