KVM: Add fpu get/set operations

These are really helpful when migrating an floating point app to another
machine.

Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 103 insertions, 0 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index e495855727e2..b065c4991568 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -2398,6 +2398,67 @@ static int kvm_vcpu_ioctl_set_sigmask(struct kvm_vcpu *vcpu, sigset_t *sigset)
         return 0;
 }
 
+/*
+ * fxsave fpu state.  Taken from x86_64/processor.h.  To be killed when
+ * we have asm/x86/processor.h
+ */
+struct fxsave {
+        u16     cwd;
+        u16     swd;
+        u16     twd;
+        u16     fop;
+        u64     rip;
+        u64     rdp;
+        u32     mxcsr;
+        u32     mxcsr_mask;
+        u32     st_space[32];   /* 8*16 bytes for each FP-reg = 128 bytes */
+#ifdef CONFIG_X86_64
+        u32     xmm_space[64];  /* 16*16 bytes for each XMM-reg = 256 bytes */
+#else
+        u32     xmm_space[32];  /* 8*16 bytes for each XMM-reg = 128 bytes */
+#endif
+};
+
+static int kvm_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
+{
+        struct fxsave *fxsave = (struct fxsave *)vcpu->guest_fx_image;
+
+        vcpu_load(vcpu);
+
+        memcpy(fpu->fpr, fxsave->st_space, 128);
+        fpu->fcw = fxsave->cwd;
+        fpu->fsw = fxsave->swd;
+        fpu->ftwx = fxsave->twd;
+        fpu->last_opcode = fxsave->fop;
+        fpu->last_ip = fxsave->rip;
+        fpu->last_dp = fxsave->rdp;
+        memcpy(fpu->xmm, fxsave->xmm_space, sizeof fxsave->xmm_space);
+
+        vcpu_put(vcpu);
+
+        return 0;
+}
+
+static int kvm_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
+{
+        struct fxsave *fxsave = (struct fxsave *)vcpu->guest_fx_image;
+
+        vcpu_load(vcpu);
+
+        memcpy(fxsave->st_space, fpu->fpr, 128);
+        fxsave->cwd = fpu->fcw;
+        fxsave->swd = fpu->fsw;
+        fxsave->twd = fpu->ftwx;
+        fxsave->fop = fpu->last_opcode;
+        fxsave->rip = fpu->last_ip;
+        fxsave->rdp = fpu->last_dp;
+        memcpy(fxsave->xmm_space, fpu->xmm, sizeof fxsave->xmm_space);
+
+        vcpu_put(vcpu);
+
+        return 0;
+}
+
 static long kvm_vcpu_ioctl(struct file *filp,
                            unsigned int ioctl, unsigned long arg)
 {
@@ -2542,6 +2603,31 @@ static long kvm_vcpu_ioctl(struct file *filp,
                 r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
                 break;
         }
+        case KVM_GET_FPU: {
+                struct kvm_fpu fpu;
+
+                memset(&fpu, 0, sizeof fpu);
+                r = kvm_vcpu_ioctl_get_fpu(vcpu, &fpu);
+                if (r)
+                        goto out;
+                r = -EFAULT;
+                if (copy_to_user(argp, &fpu, sizeof fpu))
+                        goto out;
+                r = 0;
+                break;
+        }
+        case KVM_SET_FPU: {
+                struct kvm_fpu fpu;
+
+                r = -EFAULT;
+                if (copy_from_user(&fpu, argp, sizeof fpu))
+                        goto out;
+                r = kvm_vcpu_ioctl_set_fpu(vcpu, &fpu);
+                if (r)
+                        goto out;
+                r = 0;
+                break;
+        }
         default:
                 ;
         }
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index da9b23fa4b6c..07bf353eeb6f 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -126,6 +126,21 @@ struct kvm_regs {
         __u64 rip, rflags;
 };
 
+/* for KVM_GET_FPU and KVM_SET_FPU */
+struct kvm_fpu {
+        __u8  fpr[8][16];
+        __u16 fcw;
+        __u16 fsw;
+        __u8  ftwx;  /* in fxsave format */
+        __u8  pad1;
+        __u16 last_opcode;
+        __u64 last_ip;
+        __u64 last_dp;
+        __u8  xmm[16][16];
+        __u32 mxcsr;
+        __u32 pad2;
+};
+
 struct kvm_segment {
         __u64 base;
         __u32 limit;
@@ -285,5 +300,7 @@ struct kvm_signal_mask {
 #define KVM_SET_MSRS              _IOW(KVMIO,  0x89, struct kvm_msrs)
 #define KVM_SET_CPUID             _IOW(KVMIO,  0x8a, struct kvm_cpuid)
 #define KVM_SET_SIGNAL_MASK       _IOW(KVMIO,  0x8b, struct kvm_signal_mask)
+#define KVM_GET_FPU               _IOR(KVMIO,  0x8c, struct kvm_fpu)
+#define KVM_SET_FPU               _IOW(KVMIO,  0x8d, struct kvm_fpu)
 
 #endif