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Commit 38cfd5e3 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

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



The host pkru is restored right after vcpu exit (commit 1be0e61c), 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: default avatarJunkang Fu <junkang.fjk@alibaba-inc.com>
Cc: Yang Zhang <zy107165@alibaba-inc.com>
Fixes: 1be0e61c
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b9dd21e1

arch/x86/include/asm/fpu/internal.h

+3 −3
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/x86.c

+14 −3
Original line number Diff line number Diff line
@@ -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);

			if (feature == XFEATURE_MASK_PKRU)

				memcpy(dest + offset, &vcpu->arch.pkru,

				       sizeof(vcpu->arch.pkru));

			else

				memcpy(dest + offset, src, size);



		}



		valid -= feature;
@@ -3283,6 +3288,10 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src) 
			u32 size, offset, ecx, edx;

			cpuid_count(XSTATE_CPUID, index,

				    &size, &offset, &ecx, &edx);

			if (feature == XFEATURE_MASK_PKRU)

				memcpy(&vcpu->arch.pkru, src + offset,

				       sizeof(vcpu->arch.pkru));

			else

				memcpy(dest, src + offset, size);

		}
@@ -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);

}