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KVM: x86: emulate #UD while in guest mode 

[ Upstream commit bd89525a82 ]

This reverts commits ae1f576707
and ac9b305caa.

If the hardware doesn't support MOVBE, but L0 sets CPUID.01H:ECX.MOVBE
in L1's emulated CPUID information, then L1 is likely to pass that
CPUID bit through to L2. L2 will expect MOVBE to work, but if L1
doesn't intercept #UD, then any MOVBE instruction executed in L2 will
raise #UD, and the exception will be delivered in L2.

Commit ac9b305caa is a better and more
complete version of ae1f576707 ("KVM: nVMX: Do not emulate #UD while
in guest mode"); however, neither considers the above case.

Suggested-by: Jim Mattson <jmattson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Paolo Bonzini 2018-01-11 16:55:24 +01:00 committed by Greg Kroah-Hartman
parent e9273b08d4
commit c065b9947b
2 changed files with 2 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86/kvm/svm.c
View File

@ -362,7 +362,6 @@ static void recalc_intercepts(struct vcpu_svm *svm)
{
struct vmcb_control_area *c, *h;
struct nested_state *g;
u32 h_intercept_exceptions;
mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
@ -373,14 +372,9 @@ static void recalc_intercepts(struct vcpu_svm *svm)
h = &svm->nested.hsave->control;
g = &svm->nested;
/* No need to intercept #UD if L1 doesn't intercept it */
h_intercept_exceptions =
h->intercept_exceptions & ~(1U << UD_VECTOR);
c->intercept_cr = h->intercept_cr | g->intercept_cr;
c->intercept_dr = h->intercept_dr | g->intercept_dr;
c->intercept_exceptions =
h_intercept_exceptions | g->intercept_exceptions;
c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions;
c->intercept = h->intercept | g->intercept;
}
@ -2195,7 +2189,6 @@ static int ud_interception(struct vcpu_svm *svm)
{
int er;
WARN_ON_ONCE(is_guest_mode(&svm->vcpu));
er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD);
if (er == EMULATE_USER_EXIT)
return 0;

5
arch/x86/kvm/vmx.c
View File

@ -1891,7 +1891,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
{
u32 eb;
eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) |
eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) |
(1u << DB_VECTOR) | (1u << AC_VECTOR);
if ((vcpu->guest_debug &
(KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) ==
@ -1909,8 +1909,6 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
*/
if (is_guest_mode(vcpu))
eb |= get_vmcs12(vcpu)->exception_bitmap;
else
eb |= 1u << UD_VECTOR;
vmcs_write32(EXCEPTION_BITMAP, eb);
}
@ -5921,7 +5919,6 @@ static int handle_exception(struct kvm_vcpu *vcpu)
return 1; /* already handled by vmx_vcpu_run() */
if (is_invalid_opcode(intr_info)) {
WARN_ON_ONCE(is_guest_mode(vcpu));
er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
if (er == EMULATE_USER_EXIT)
return 0;