Commit 6ca9bcfe authored Nov 05, 2017 by Liran Alon Committed by Greg Kroah-Hartman Feb 07, 2018

KVM: x86: Don't re-execute instruction when not passing CR2 value




[ Upstream commit 9b8ae63798cb97e785a667ff27e43fa6220cb734 ]

In case of instruction-decode failure or emulation failure,
x86_emulate_instruction() will call reexecute_instruction() which will
attempt to use the cr2 value passed to x86_emulate_instruction().
However, when x86_emulate_instruction() is called from
emulate_instruction(), cr2 is not passed (passed as 0) and therefore
it doesn't make sense to execute reexecute_instruction() logic at all.

Fixes: 51d8b661 ("KVM: cleanup emulate_instruction")

Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent c786c16d

arch/x86/include/asm/kvm_host.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -849,7 +849,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
		static inline int emulate_instruction(struct kvm_vcpu *vcpu,
		int emulation_type)
		{
		return x86_emulate_instruction(vcpu, 0, emulation_type, NULL, 0);
		return x86_emulate_instruction(vcpu, 0,
		emulation_type \| EMULTYPE_NO_REEXECUTE, NULL, 0);
		}

		void kvm_enable_efer_bits(u64);

arch/x86/kvm/vmx.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5707,7 +5707,7 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
		if (test_bit(KVM_REQ_EVENT, &vcpu->requests))
		return 1;

		err = emulate_instruction(vcpu, EMULTYPE_NO_REEXECUTE);
		err = emulate_instruction(vcpu, 0);

		if (err == EMULATE_USER_EXIT) {
		++vcpu->stat.mmio_exits;