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KVM, pkeys: do not use PKRU value in vcpu->arch.guest_fpu.state

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The host pkru is restored right after vcpu exit (commit 1be0e61), so
KVM_GET_XSAVE will return the host PKRU value instead.  Fix this by
using the guest PKRU explicitly in fill_xsave and load_xsave.  This
part is based on a patch by Junkang Fu.

The host PKRU data may also not match the value in vcpu->arch.guest_fpu.state,
because it could have been changed by userspace since the last time
it was saved, so skip loading it in kvm_load_guest_fpu.

Reported-by: Junkang Fu <junkang.fjk@alibaba-inc.com>
Cc: Yang Zhang <zy107165@alibaba-inc.com>
Fixes: 1be0e61c1f
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-08-23 23:16:29 +02:00
parent b9dd21e104
commit 38cfd5e3df
2 changed files with 17 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
arch/x86/include/asm/fpu/internal.h
View file

@ -450,10 +450,10 @@ static inline int copy_fpregs_to_fpstate(struct fpu *fpu)
return 0;
}
static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate)
static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate, u64 mask)
{
if (use_xsave()) {
copy_kernel_to_xregs(&fpstate->xsave, -1);
copy_kernel_to_xregs(&fpstate->xsave, mask);
} else {
if (use_fxsr())
copy_kernel_to_fxregs(&fpstate->fxsave);
@ -477,7 +477,7 @@ static inline void copy_kernel_to_fpregs(union fpregs_state *fpstate)
: : [addr] "m" (fpstate));
}
__copy_kernel_to_fpregs(fpstate);
__copy_kernel_to_fpregs(fpstate, -1);
}
extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size);

17
arch/x86/kvm/x86.c
View file

@ -3245,7 +3245,12 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
u32 size, offset, ecx, edx;
cpuid_count(XSTATE_CPUID, index,
&size, &offset, &ecx, &edx);
memcpy(dest + offset, src, size);
if (feature == XFEATURE_MASK_PKRU)
memcpy(dest + offset, &vcpu->arch.pkru,
sizeof(vcpu->arch.pkru));
else
memcpy(dest + offset, src, size);
}
valid -= feature;
@ -3283,7 +3288,11 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
u32 size, offset, ecx, edx;
cpuid_count(XSTATE_CPUID, index,
&size, &offset, &ecx, &edx);
memcpy(dest, src + offset, size);
if (feature == XFEATURE_MASK_PKRU)
memcpy(&vcpu->arch.pkru, src + offset,
sizeof(vcpu->arch.pkru));
else
memcpy(dest, src + offset, size);
}
valid -= feature;
@ -7633,7 +7642,9 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
*/
vcpu->guest_fpu_loaded = 1;
__kernel_fpu_begin();
__copy_kernel_to_fpregs(&vcpu->arch.guest_fpu.state);
/* PKRU is separately restored in kvm_x86_ops->run. */
__copy_kernel_to_fpregs(&vcpu->arch.guest_fpu.state,
~XFEATURE_MASK_PKRU);
trace_kvm_fpu(1);
}