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authorPaolo Bonzini <pbonzini@redhat.com>2020-09-29 08:31:32 -0400
committerPaolo Bonzini <pbonzini@redhat.com>2020-10-03 05:07:40 -0400
commitb502e6ecdc3b6d381bd72c5f879bc1e00d6fe7db (patch)
treeee7378f38763f315a253ef615ea26cc163c41bed /arch
parent4bb05f30483fd21ea5413eaf1182768f251cf625 (diff)
KVM: VMX: update PFEC_MASK/PFEC_MATCH together with PF intercept
The PFEC_MASK and PFEC_MATCH fields in the VMCS reverse the meaning of the #PF intercept bit in the exception bitmap when they do not match. This means that, if PFEC_MASK and/or PFEC_MATCH are set, the hypervisor can get a vmexit for #PF exceptions even when the corresponding bit is clear in the exception bitmap. This is unexpected and is promptly detected by a WARN_ON_ONCE. To fix it, reset PFEC_MASK and PFEC_MATCH when the #PF intercept is disabled (as is common with enable_ept && !allow_smaller_maxphyaddr). Reported-by: Qian Cai <cai@redhat.com>> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/vmx/vmx.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f0384e93548a..f4e9c310032a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -794,6 +794,18 @@ void update_exception_bitmap(struct kvm_vcpu *vcpu)
*/
if (is_guest_mode(vcpu))
eb |= get_vmcs12(vcpu)->exception_bitmap;
+ else {
+ /*
+ * If EPT is enabled, #PF is only trapped if MAXPHYADDR is mismatched
+ * between guest and host. In that case we only care about present
+ * faults. For vmcs02, however, PFEC_MASK and PFEC_MATCH are set in
+ * prepare_vmcs02_rare.
+ */
+ bool selective_pf_trap = enable_ept && (eb & (1u << PF_VECTOR));
+ int mask = selective_pf_trap ? PFERR_PRESENT_MASK : 0;
+ vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, mask);
+ vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, mask);
+ }
vmcs_write32(EXCEPTION_BITMAP, eb);
}
@@ -4355,16 +4367,6 @@ static void init_vmcs(struct vcpu_vmx *vmx)
vmx->pt_desc.guest.output_mask = 0x7F;
vmcs_write64(GUEST_IA32_RTIT_CTL, 0);
}
-
- /*
- * If EPT is enabled, #PF is only trapped if MAXPHYADDR is mismatched
- * between guest and host. In that case we only care about present
- * faults.
- */
- if (enable_ept) {
- vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, PFERR_PRESENT_MASK);
- vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, PFERR_PRESENT_MASK);
- }
}
static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)