[PATCH] KVM: x86: XSAVE/XRSTOR live migration support

[Sheng Yang <sheng@linux.intel.com>]

This patch enable save/restore of xsave state.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---
 arch/x86/include/asm/kvm.h |   29 ++++++++++++++++
 arch/x86/kvm/x86.c         |   79 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/kvm.h        |    6 +++
 3 files changed, 114 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index ff90055..d3f4d9f 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -22,6 +22,7 @@
 #define __KVM_HAVE_XEN_HVM
 #define __KVM_HAVE_VCPU_EVENTS
 #define __KVM_HAVE_DEBUGREGS
+#define __KVM_HAVE_XSAVE
 
 /* Architectural interrupt line count. */
 #define KVM_NR_INTERRUPTS 256
@@ -299,4 +300,32 @@ struct kvm_debugregs {
 	__u64 reserved[9];
 };
 
+/* for KVM_CAP_XSAVE */
+struct kvm_xsave {
+	struct {
+		__u16 cwd;
+		__u16 swd;
+		__u16 twd;
+		__u16 fop;
+		__u64 rip;
+		__u64 rdp;
+		__u32 mxcsr;
+		__u32 mxcsr_mask;
+		__u32 st_space[32];
+		__u32 xmm_space[64];
+		__u32 padding[12];
+		__u32 sw_reserved[12];
+	} i387;
+	struct {
+		__u64 xstate_bv;
+		__u64 reserved1[2];
+		__u64 reserved2[5];
+	} xsave_hdr;
+	struct {
+		__u32 ymmh_space[64];
+	} ymmh;
+	__u64 xcr0;
+	__u32 padding[256];
+};
+
 #endif /* _ASM_X86_KVM_H */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e7acc9d..5badba2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1711,6 +1711,9 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_MCE:
 		r = KVM_MAX_MCE_BANKS;
 		break;
+	case KVM_CAP_XSAVE:
+		r = cpu_has_xsave;
+		break;
 	default:
 		r = 0;
 		break;
@@ -2363,6 +2366,59 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
+static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
+					struct kvm_xsave *guest_xsave)
+{
+	struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave;
+
+	if (!cpu_has_xsave)
+		return;
+
+	guest_xsave->i387.cwd = xsave->i387.cwd;
+	guest_xsave->i387.swd = xsave->i387.swd;
+	guest_xsave->i387.twd = xsave->i387.twd;
+	guest_xsave->i387.fop = xsave->i387.fop;
+	guest_xsave->i387.rip = xsave->i387.rip;
+	guest_xsave->i387.rdp = xsave->i387.rdp;
+	memcpy(guest_xsave->i387.st_space, xsave->i387.st_space, 128);
+	memcpy(guest_xsave->i387.xmm_space, xsave->i387.xmm_space,
+			sizeof guest_xsave->i387.xmm_space);
+
+	guest_xsave->xsave_hdr.xstate_bv = xsave->xsave_hdr.xstate_bv;
+	memcpy(guest_xsave->ymmh.ymmh_space, xsave->ymmh.ymmh_space,
+			sizeof xsave->ymmh.ymmh_space);
+
+	guest_xsave->xcr0 = vcpu->arch.xcr0;
+}
+
+static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
+					struct kvm_xsave *guest_xsave)
+{
+	struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave;
+
+	if (!cpu_has_xsave)
+		return -EINVAL;
+
+	xsave->i387.cwd = guest_xsave->i387.cwd;
+	xsave->i387.swd = guest_xsave->i387.swd;
+	xsave->i387.twd = guest_xsave->i387.twd;
+	xsave->i387.fop = guest_xsave->i387.fop;
+	xsave->i387.rip = guest_xsave->i387.rip;
+	xsave->i387.rdp = guest_xsave->i387.rdp;
+	memcpy(xsave->i387.st_space, guest_xsave->i387.st_space, 128);
+	memcpy(xsave->i387.xmm_space, guest_xsave->i387.xmm_space,
+			sizeof guest_xsave->i387.xmm_space);
+
+	xsave->xsave_hdr.xstate_bv = guest_xsave->xsave_hdr.xstate_bv;
+	memcpy(xsave->ymmh.ymmh_space, guest_xsave->ymmh.ymmh_space,
+		sizeof guest_xsave->ymmh.ymmh_space);
+
+	/* set_xsave may override the initial value of xcr0... */
+	if (guest_xsave->xcr0 != 0)
+		kvm_set_xcr0(vcpu, guest_xsave->xcr0);
+	return 0;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg)
 {
@@ -2564,6 +2620,29 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		r = kvm_vcpu_ioctl_x86_set_debugregs(vcpu, &dbgregs);
 		break;
 	}
+	case KVM_GET_XSAVE: {
+		struct kvm_xsave xsave;
+
+		kvm_vcpu_ioctl_x86_get_xsave(vcpu, &xsave);
+
+		r = -EFAULT;
+		if (copy_to_user(argp, &xsave,
+				 sizeof(struct kvm_xsave)))
+			break;
+		r = 0;
+		break;
+	}
+	case KVM_SET_XSAVE: {
+		struct kvm_xsave xsave;
+
+		r = -EFAULT;
+		if (copy_from_user(&xsave, argp,
+				   sizeof(struct kvm_xsave)))
+			break;
+
+		r = kvm_vcpu_ioctl_x86_set_xsave(vcpu, &xsave);
+		break;
+	}
 	default:
 		r = -EINVAL;
 	}
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 23ea022..5006761 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -524,6 +524,9 @@ struct kvm_enable_cap {
 #define KVM_CAP_PPC_OSI 52
 #define KVM_CAP_PPC_UNSET_IRQ 53
 #define KVM_CAP_ENABLE_CAP 54
+#ifdef __KVM_HAVE_XSAVE
+#define KVM_CAP_XSAVE 55
+#endif
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -714,6 +717,9 @@ struct kvm_clock_data {
 #define KVM_GET_DEBUGREGS         _IOR(KVMIO,  0xa1, struct kvm_debugregs)
 #define KVM_SET_DEBUGREGS         _IOW(KVMIO,  0xa2, struct kvm_debugregs)
 #define KVM_ENABLE_CAP            _IOW(KVMIO,  0xa3, struct kvm_enable_cap)
+/* Available with KVM_CAP_XSAVE */
+#define KVM_GET_XSAVE		  _IOR(KVMIO,  0xa4, struct kvm_xsave)
+#define KVM_SET_XSAVE		  _IOW(KVMIO,  0xa5, struct kvm_xsave)
 
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
 
-- 
1.7.0.1