Commit 2f0a6397 authored Dec 30, 2013 by Zhihui Zhang Committed by Marcelo Tosatti Jan 08, 2014

KVM: VMX: check use I/O bitmap first before unconditional I/O exit

According to Table C-1 of Intel SDM 3C, a VM exit happens on an I/O instruction when
"use I/O bitmaps" VM-execution control was 0 _and_ the "unconditional I/O exiting"
VM-execution control was 1. So we can't just check "unconditional I/O exiting" alone.
This patch was improved by suggestion from Jan Kiszka.

Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent 17180032

arch/x86/kvm/vmx.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -6521,11 +6521,8 @@ static bool nested_vmx_exit_handled_io(struct kvm_vcpu *vcpu,
		int size;
		u8 b;

		if (nested_cpu_has(vmcs12, CPU_BASED_UNCOND_IO_EXITING))
		return 1;

		if (!nested_cpu_has(vmcs12, CPU_BASED_USE_IO_BITMAPS))
		return 0;
		return nested_cpu_has(vmcs12, CPU_BASED_UNCOND_IO_EXITING);

		exit_qualification = vmcs_readl(EXIT_QUALIFICATION);