x86/fpu: Replace KVMs home brewed FPU copy to user

Similar to the copy from user function the FPU core has this already
implemented with all bells and whistles.

Get rid of the duplicated code and use the core functionality.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: kvm@vger.kernel.org
Link: https://lkml.kernel.org/r/20211015011539.244101845@linutronix.de

diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index 9263d708dff9a5f04418c8d72e851a4b9c5712df..5ac5e4596b536d5ca9ea3473dc41cb6e0c01eb12 100644 (file)
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -137,5 +137,6 @@ extern void fpu_init_fpstate_user(struct fpu *fpu);
 extern void fpu_swap_kvm_fpu(struct fpu *save, struct fpu *rstor, u64 restore_mask);
 
 extern int fpu_copy_kvm_uabi_to_fpstate(struct fpu *fpu, const void *buf, u64 xcr0, u32 *pkru);
+extern void fpu_copy_fpstate_to_kvm_uabi(struct fpu *fpu, void *buf, unsigned int size, u32 pkru);
 
 #endif /* _ASM_X86_FPU_API_H */

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 79f2e8ddd10cb7a1334dfd806e35b2737a864651..ac540a7d410e512d0a090736e826153c20645f29 100644 (file)
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -184,6 +184,24 @@ void fpu_swap_kvm_fpu(struct fpu *save, struct fpu *rstor, u64 restore_mask)
 }
 EXPORT_SYMBOL_GPL(fpu_swap_kvm_fpu);
 
+void fpu_copy_fpstate_to_kvm_uabi(struct fpu *fpu, void *buf,
+                              unsigned int size, u32 pkru)
+{
+       union fpregs_state *kstate = &fpu->state;
+       union fpregs_state *ustate = buf;
+       struct membuf mb = { .p = buf, .left = size };
+
+       if (cpu_feature_enabled(X86_FEATURE_XSAVE)) {
+               __copy_xstate_to_uabi_buf(mb, &kstate->xsave, pkru,
+                                         XSTATE_COPY_XSAVE);
+       } else {
+               memcpy(&ustate->fxsave, &kstate->fxsave, sizeof(ustate->fxsave));
+               /* Make it restorable on a XSAVE enabled host */
+               ustate->xsave.header.xfeatures = XFEATURE_MASK_FPSSE;
+       }
+}
+EXPORT_SYMBOL_GPL(fpu_copy_fpstate_to_kvm_uabi);
+
 int fpu_copy_kvm_uabi_to_fpstate(struct fpu *fpu, const void *buf, u64 xcr0,
                                 u32 *vpkru)
 {

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cdc19b1d5775992a4294eae40b74aa77b8355053..a18d4670e640417be9c18a8cff792ccf685fc111 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4702,65 +4702,15 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
        return 0;
 }
 
-static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
-{
-       struct xregs_state *xsave = &vcpu->arch.guest_fpu->state.xsave;
-       u64 xstate_bv = xsave->header.xfeatures;
-       u64 valid;
-
-       /*
-        * Copy legacy XSAVE area, to avoid complications with CPUID
-        * leaves 0 and 1 in the loop below.
-        */
-       memcpy(dest, xsave, XSAVE_HDR_OFFSET);
-
-       /* Set XSTATE_BV */
-       xstate_bv &= vcpu->arch.guest_supported_xcr0 | XFEATURE_MASK_FPSSE;
-       *(u64 *)(dest + XSAVE_HDR_OFFSET) = xstate_bv;
-
-       /*
-        * Copy each region from the possibly compacted offset to the
-        * non-compacted offset.
-        */
-       valid = xstate_bv & ~XFEATURE_MASK_FPSSE;
-       while (valid) {
-               u32 size, offset, ecx, edx;
-               u64 xfeature_mask = valid & -valid;
-               int xfeature_nr = fls64(xfeature_mask) - 1;
-               void *src;
-
-               cpuid_count(XSTATE_CPUID, xfeature_nr,
-                           &size, &offset, &ecx, &edx);
-
-               if (xfeature_nr == XFEATURE_PKRU) {
-                       memcpy(dest + offset, &vcpu->arch.pkru,
-                              sizeof(vcpu->arch.pkru));
-               } else {
-                       src = get_xsave_addr(xsave, xfeature_nr);
-                       if (src)
-                               memcpy(dest + offset, src, size);
-               }
-
-               valid -= xfeature_mask;
-       }
-}
-
 static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
                                         struct kvm_xsave *guest_xsave)
 {
        if (!vcpu->arch.guest_fpu)
                return;
 
-       if (boot_cpu_has(X86_FEATURE_XSAVE)) {
-               memset(guest_xsave, 0, sizeof(struct kvm_xsave));
-               fill_xsave((u8 *) guest_xsave->region, vcpu);
-       } else {
-               memcpy(guest_xsave->region,
-                       &vcpu->arch.guest_fpu->state.fxsave,
-                       sizeof(struct fxregs_state));
-               *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)] =
-                       XFEATURE_MASK_FPSSE;
-       }
+       fpu_copy_fpstate_to_kvm_uabi(vcpu->arch.guest_fpu, guest_xsave->region,
+                                    sizeof(guest_xsave->region),
+                                    vcpu->arch.pkru);
 }
 
 static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,