Commit 47c28d43 authored by Denis Valeev's avatar Denis Valeev Committed by Paolo Bonzini
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KVM: x86: nSVM: skip eax alignment check for non-SVM instructions 



The bug occurs on #GP triggered by VMware backdoor when eax value is
unaligned. eax alignment check should not be applied to non-SVM
instructions because it leads to incorrect omission of the instructions
emulation.
Apply the alignment check only to SVM instructions to fix.

Fixes: d1cba6c9 ("KVM: x86: nSVM: test eax for 4K alignment for GP errata workaround")
Signed-off-by: default avatarDenis Valeev <lemniscattaden@gmail.com>
Message-Id: <Yexlhaoe1Fscm59u@q>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 1ffce092

arch/x86/kvm/svm/svm.c

+6 −5
Original line number Diff line number Diff line
@@ -2091,10 +2091,6 @@ static int gp_interception(struct kvm_vcpu *vcpu) 
	if (error_code)

		goto reinject;



	/* All SVM instructions expect page aligned RAX */

	if (svm->vmcb->save.rax & ~PAGE_MASK)

		goto reinject;



	/* Decode the instruction for usage later */

	if (x86_decode_emulated_instruction(vcpu, 0, NULL, 0) != EMULATION_OK)

		goto reinject;
@@ -2112,8 +2108,13 @@ static int gp_interception(struct kvm_vcpu *vcpu) 
		if (!is_guest_mode(vcpu))

			return kvm_emulate_instruction(vcpu,

				EMULTYPE_VMWARE_GP | EMULTYPE_NO_DECODE);

	} else

	} else {

		/* All SVM instructions expect page aligned RAX */

		if (svm->vmcb->save.rax & ~PAGE_MASK)

			goto reinject;



		return emulate_svm_instr(vcpu, opcode);

	}



reinject:

	kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);