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KVM: VMX: check descriptor table exits on instruction emulation 

commit 86f7e90ce8 upstream.

KVM emulates UMIP on hardware that doesn't support it by setting the
'descriptor table exiting' VM-execution control and performing
instruction emulation. When running nested, this emulation is broken as
KVM refuses to emulate L2 instructions by default.

Correct this regression by allowing the emulation of descriptor table
instructions if L1 hasn't requested 'descriptor table exiting'.

Fixes: 07721feee4 ("KVM: nVMX: Don't emulate instructions in guest mode")
Reported-by: Jan Kiszka <jan.kiszka@web.de>
Cc: stable@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Oliver Upton 2020-02-29 11:30:14 -08:00 committed by Greg Kroah-Hartman
parent 07fec9a84c
commit 9154d430dc
1 changed files with 15 additions and 0 deletions
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15
arch/x86/kvm/vmx/vmx.c
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@ -7165,6 +7165,7 @@ static int vmx_check_intercept_io(struct kvm_vcpu *vcpu,
else
intercept = nested_vmx_check_io_bitmaps(vcpu, port, size);
/* FIXME: produce nested vmexit and return X86EMUL_INTERCEPTED. */
return intercept ? X86EMUL_UNHANDLEABLE : X86EMUL_CONTINUE;
}
@ -7194,6 +7195,20 @@ static int vmx_check_intercept(struct kvm_vcpu *vcpu,
case x86_intercept_outs:
return vmx_check_intercept_io(vcpu, info);
case x86_intercept_lgdt:
case x86_intercept_lidt:
case x86_intercept_lldt:
case x86_intercept_ltr:
case x86_intercept_sgdt:
case x86_intercept_sidt:
case x86_intercept_sldt:
case x86_intercept_str:
if (!nested_cpu_has2(vmcs12, SECONDARY_EXEC_DESC))
return X86EMUL_CONTINUE;
/* FIXME: produce nested vmexit and return X86EMUL_INTERCEPTED. */
break;
/* TODO: check more intercepts... */
default:
break;