[PATCH 16/19] kvm: x86: Introduce KVM_{G|S}ET_XSAVE2 ioctl

Yang Zhong
2021-12-07T15:10:52Z

From: Jing Liu <jing2.liu@intel.com>

When dynamic XSTATE features are supported, the xsave states are
beyond 4KB. The current kvm_xsave structure and related
KVM_{G, S}ET_XSAVE only allows 4KB which is not enough for full
states.

Introduce a new kvm_xsave2 structure and the corresponding
KVM_GET_XSAVE2 and KVM_SET_XSAVE2 ioctls so that userspace VMM
can get and set the full xsave states.

Signed-off-by: Jing Liu <jing2.liu@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
arch/x86/include/uapi/asm/kvm.h | 6 ++++
arch/x86/kvm/x86.c | 62 +++++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 7 +++-
3 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 5a776a08f78c..de42a51e20c3 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -47,6 +47,7 @@
#define __KVM_HAVE_VCPU_EVENTS
#define __KVM_HAVE_DEBUGREGS
#define __KVM_HAVE_XSAVE
+#define __KVM_HAVE_XSAVE2
#define __KVM_HAVE_XCRS
#define __KVM_HAVE_READONLY_MEM

@@ -378,6 +379,11 @@ struct kvm_xsave {
__u32 region[1024];
};

+struct kvm_xsave2 {
+ __u32 size;
+ __u8 state[0];
+};
+
#define KVM_MAX_XCRS 16

struct kvm_xcr {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8b033c9241d6..d212f6d2d39a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4216,6 +4216,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_DEBUGREGS:
case KVM_CAP_X86_ROBUST_SINGLESTEP:
case KVM_CAP_XSAVE:
+ case KVM_CAP_XSAVE2:
case KVM_CAP_ASYNC_PF:
case KVM_CAP_ASYNC_PF_INT:
case KVM_CAP_GET_TSC_KHZ:
@@ -4940,6 +4941,17 @@ 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, u32 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)
{
@@ -4951,6 +4963,15 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
supported_xcr0, &vcpu->arch.pkru);
}

+static int kvm_vcpu_ioctl_x86_set_xsave2(struct kvm_vcpu *vcpu, u8 *state)
+{
+ if (fpstate_is_confidential(&vcpu->arch.guest_fpu))
+ return 0;
+
+ return fpu_copy_uabi_to_guest_fpstate(&vcpu->arch.guest_fpu, state,
+ supported_xcr0, &vcpu->arch.pkru);
+}
+
static void kvm_vcpu_ioctl_x86_get_xcrs(struct kvm_vcpu *vcpu,
struct kvm_xcrs *guest_xcrs)
{
@@ -5416,6 +5437,47 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
r = kvm_vcpu_ioctl_x86_set_xsave(vcpu, u.xsave);
break;
}
+ case KVM_GET_XSAVE2: {
+ struct kvm_xsave2 __user *xsave2_arg = argp;
+ struct kvm_xsave2 xsave2;
+
+ r = -EFAULT;
+ if (copy_from_user(&xsave2, xsave2_arg, sizeof(struct kvm_xsave2)))
+ break;
+
+ u.buffer = kzalloc(xsave2.size, GFP_KERNEL_ACCOUNT);
+
+ r = -ENOMEM;
+ if (!u.buffer)
+ break;
+
+ kvm_vcpu_ioctl_x86_get_xsave2(vcpu, u.buffer, xsave2.size);
+
+ r = -EFAULT;
+ if (copy_to_user(xsave2_arg->state, u.buffer, xsave2.size))
+ break;
+
+ r = 0;
+ break;
+ }
+ case KVM_SET_XSAVE2: {
+ struct kvm_xsave2 __user *xsave2_arg = argp;
+ struct kvm_xsave2 xsave2;
+
+ r = -EFAULT;
+ if (copy_from_user(&xsave2, xsave2_arg, sizeof(struct kvm_xsave2)))
+ break;
+
+ u.buffer = memdup_user(xsave2_arg->state, xsave2.size);
+
+ if (IS_ERR(u.buffer)) {
+ r = PTR_ERR(u.buffer);
+ goto out_nofree;
+ }
+
+ r = kvm_vcpu_ioctl_x86_set_xsave2(vcpu, u.buffer);
+ 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 0c7b301c7254..603e1ca9ba09 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1132,7 +1132,9 @@ 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
-
+#ifdef __KVM_HAVE_XSAVE2
+#define KVM_CAP_XSAVE2 207
+#endif
#ifdef KVM_CAP_IRQ_ROUTING

struct kvm_irq_routing_irqchip {
@@ -1679,6 +1681,9 @@ struct kvm_xen_hvm_attr {
#define KVM_GET_SREGS2 _IOR(KVMIO, 0xcc, struct kvm_sregs2)
#define KVM_SET_SREGS2 _IOW(KVMIO, 0xcd, struct kvm_sregs2)

+#define KVM_GET_XSAVE2 _IOR(KVMIO, 0xcf, struct kvm_xsave2)
+#define KVM_SET_XSAVE2 _IOW(KVMIO, 0xd0, struct kvm_xsave2)
+
struct kvm_xen_vcpu_attr {
__u16 type;
__u16 pad[3];