From 86f7e90ce840aa1db407d3ea6e9b3a52b2ce923c Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Sat, 29 Feb 2020 11:30:14 -0800 Subject: [PATCH] KVM: VMX: check descriptor table exits on instruction emulation 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: 07721feee46b ("KVM: nVMX: Don't emulate instructions in guest mode") Reported-by: Jan Kiszka Cc: stable@vger.kernel.org Cc: Paolo Bonzini Cc: Jim Mattson Signed-off-by: Oliver Upton Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmx.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index ce70a71037ed..40b1e6138cd5 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7177,6 +7177,7 @@ 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; } @@ -7206,6 +7207,20 @@ 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;