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| author | Paolo Bonzini <pbonzini@redhat.com> | 2020-09-29 15:31:32 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-10-03 12:07:40 +0300 |
| commit | b502e6ecdc3b6d381bd72c5f879bc1e00d6fe7db (patch) | |
| tree | ee7378f38763f315a253ef615ea26cc163c41bed | |
| parent | 4bb05f30483fd21ea5413eaf1182768f251cf625 (diff) | |
| download | linux-b502e6ecdc3b6d381bd72c5f879bc1e00d6fe7db.tar.xz | |
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>
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 22 |
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) |