From: Guang Zeng guang.zeng@intel.com
When AMX is enabled it requires a larger xstate buffer than the legacy hardcoded 4KB one. Exising kvm ioctls (KVM_[G|S]ET_XSAVE under KVM_CAP_XSAVE) are not suitable for this purpose.
A new capability (KVM_CAP_XSAVE2) is introduced to mark an extended kvm_xsave format to support >4KB fpstate. The expanded fpstate size is returned to userspace when it checks the KVM_CAP_XSAVE2 capability.
Introduce a new KVM_GET_XSAVE2 under this capability to use the new format for copying guest fpstate to userspace. Reuse KVM_SET_XSAVE for both old/new formats by reimplementing it to do properly-sized memdup_user() based on the guest fpu container.
Also, update the api doc with the new KVM_GET_XSAVE2 ioctl.
Signed-off-by: Guang Zeng guang.zeng@intel.com Signed-off-by: Wei Wang wei.w.wang@intel.com Signed-off-by: Jing Liu jing2.liu@intel.com --- Documentation/virt/kvm/api.rst | 42 +++++++++++++++++++++++++++++++-- arch/x86/include/uapi/asm/kvm.h | 16 ++++++++++++- arch/x86/kvm/x86.c | 39 +++++++++++++++++++++++++++++- include/uapi/linux/kvm.h | 4 ++++ 4 files changed, 97 insertions(+), 4 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 1cf2483246cd..e48f7de5f23a 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1566,6 +1566,7 @@ otherwise it will return EBUSY error.
struct kvm_xsave { __u32 region[1024]; + __u32 extra[0]; };
This ioctl would copy current vcpu's xsave struct to the userspace. @@ -1574,7 +1575,7 @@ This ioctl would copy current vcpu's xsave struct to the userspace. 4.43 KVM_SET_XSAVE ------------------
-:Capability: KVM_CAP_XSAVE +:Capability: KVM_CAP_XSAVE and KVM_CAP_XSAVE2 :Architectures: x86 :Type: vcpu ioctl :Parameters: struct kvm_xsave (in) @@ -1585,9 +1586,18 @@ This ioctl would copy current vcpu's xsave struct to the userspace.
struct kvm_xsave { __u32 region[1024]; + __u32 extra[0]; };
-This ioctl would copy userspace's xsave struct to the kernel. +This ioctl would copy userspace's xsave struct to the kernel. It copies +as many bytes as are returned by KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2), +when invoked on the vm file descriptor. The size value returned by +KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) will always be at least 4096. +Currently, it is only greater than 4096 if a dynamic feature has been +enabled with ``arch_prctl()``, but this may change in the future. + +The offsets of the state save areas in struct kvm_xsave follow the +contents of CPUID leaf 0xD on the host.
4.44 KVM_GET_XCRS @@ -5507,6 +5517,34 @@ the trailing ``'\0'``, is indicated by ``name_size`` in the header. The Stats Data block contains an array of 64-bit values in the same order as the descriptors in Descriptors block.
+4.42 KVM_GET_XSAVE2 +------------------ + +:Capability: KVM_CAP_XSAVE2 +:Architectures: x86 +:Type: vcpu ioctl +:Parameters: struct kvm_xsave (out) +:Returns: 0 on success, -1 on error + + +:: + + struct kvm_xsave { + __u32 region[1024]; + __u32 extra[0]; + }; + +This ioctl would copy current vcpu's xsave struct to the userspace. It +copies as many bytes as are returned by KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) +when invoked on the vm file descriptor. The size value returned by +KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) will always be at least 4096. +Currently, it is only greater than 4096 if a dynamic feature has been +enabled with ``arch_prctl()``, but this may change in the future. + +The offsets of the state save areas in struct kvm_xsave follow the contents +of CPUID leaf 0xD on the host. + + 5. The kvm_run structure ========================
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index 5a776a08f78c..2da3316bb559 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -373,9 +373,23 @@ struct kvm_debugregs { __u64 reserved[9]; };
-/* for KVM_CAP_XSAVE */ +/* for KVM_CAP_XSAVE and KVM_CAP_XSAVE2 */ struct kvm_xsave { + /* + * KVM_GET_XSAVE2 and KVM_SET_XSAVE write and read as many bytes + * as are returned by KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) + * respectively, when invoked on the vm file descriptor. + * + * The size value returned by KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) + * will always be at least 4096. Currently, it is only greater + * than 4096 if a dynamic feature has been enabled with + * ``arch_prctl()``, but this may change in the future. + * + * The offsets of the state save areas in struct kvm_xsave follow + * the contents of CPUID leaf 0xD on the host. + */ __u32 region[1024]; + __u32 extra[0]; };
#define KVM_MAX_XCRS 16 diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c558c098979a..3b756ff13103 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4297,6 +4297,11 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) else r = 0; break; + case KVM_CAP_XSAVE2: + r = kvm->vcpus[0]->arch.guest_fpu.uabi_size; + if (r < sizeof(struct kvm_xsave)) + r = sizeof(struct kvm_xsave); + break; default: break; } @@ -4900,6 +4905,16 @@ static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu, vcpu->arch.pkru); }
+static void kvm_vcpu_ioctl_x86_get_xsave2(struct kvm_vcpu *vcpu, + u8 *state, unsigned int size) +{ + if (fpstate_is_confidential(&vcpu->arch.guest_fpu)) + return; + + fpu_copy_guest_fpstate_to_uabi(&vcpu->arch.guest_fpu, + state, size, vcpu->arch.pkru); +} + static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu, struct kvm_xsave *guest_xsave) { @@ -5367,7 +5382,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp, break; } case KVM_SET_XSAVE: { - u.xsave = memdup_user(argp, sizeof(*u.xsave)); + int size = vcpu->arch.guest_fpu.uabi_size; + + u.xsave = memdup_user(argp, size); if (IS_ERR(u.xsave)) { r = PTR_ERR(u.xsave); goto out_nofree; @@ -5376,6 +5393,26 @@ long kvm_arch_vcpu_ioctl(struct file *filp, r = kvm_vcpu_ioctl_x86_set_xsave(vcpu, u.xsave); break; } + + case KVM_GET_XSAVE2: { + int size = vcpu->arch.guest_fpu.uabi_size; + + u.xsave = kzalloc(size, GFP_KERNEL_ACCOUNT); + if (!u.xsave) { + r = -ENOMEM; + break; + } + + kvm_vcpu_ioctl_x86_get_xsave2(vcpu, u.buffer, size); + + if (copy_to_user(argp, u.xsave, size)) { + r = -EFAULT; + break; + } + r = 0; + break; + } + case KVM_GET_XCRS: { u.xcrs = kzalloc(sizeof(struct kvm_xcrs), GFP_KERNEL_ACCOUNT); r = -ENOMEM; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 1daa45268de2..9d1c01669560 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204 #define KVM_CAP_ARM_MTE 205 #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206 +#define KVM_CAP_XSAVE2 207
#ifdef KVM_CAP_IRQ_ROUTING
@@ -1610,6 +1611,9 @@ struct kvm_enc_region { #define KVM_S390_NORMAL_RESET _IO(KVMIO, 0xc3) #define KVM_S390_CLEAR_RESET _IO(KVMIO, 0xc4)
+/* Available with KVM_CAP_XSAVE2 */ +#define KVM_GET_XSAVE2 _IOR(KVMIO, 0xcf, struct kvm_xsave) + struct kvm_s390_pv_sec_parm { __u64 origin; __u64 length;