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Commitb502e6e

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KVM: VMX: update PFEC_MASK/PFEC_MATCH together with PF intercept
The PFEC_MASK and PFEC_MATCH fields in the VMCS reverse the meaning ofthe #PF intercept bit in the exception bitmap when they do not match.This means that, if PFEC_MASK and/or PFEC_MATCH are set, thehypervisor can get a vmexit for #PF exceptions even when thecorresponding 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 interceptis 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>
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‎arch/x86/kvm/vmx/vmx.c‎

Lines changed: 12 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -794,6 +794,18 @@ void update_exception_bitmap(struct kvm_vcpu *vcpu)
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*/
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if (is_guest_mode(vcpu))
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eb |=get_vmcs12(vcpu)->exception_bitmap;
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else {
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/*
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* If EPT is enabled, #PF is only trapped if MAXPHYADDR is mismatched
800+
* between guest and host. In that case we only care about present
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* faults. For vmcs02, however, PFEC_MASK and PFEC_MATCH are set in
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* prepare_vmcs02_rare.
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*/
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boolselective_pf_trap=enable_ept&& (eb& (1u <<PF_VECTOR));
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intmask=selective_pf_trap ?PFERR_PRESENT_MASK :0;
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vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK,mask);
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vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH,mask);
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}
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vmcs_write32(EXCEPTION_BITMAP,eb);
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}
@@ -4355,16 +4367,6 @@ static void init_vmcs(struct vcpu_vmx *vmx)
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vmx->pt_desc.guest.output_mask=0x7F;
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vmcs_write64(GUEST_IA32_RTIT_CTL,0);
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}
4358-
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/*
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* If EPT is enabled, #PF is only trapped if MAXPHYADDR is mismatched
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* between guest and host. In that case we only care about present
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* faults.
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*/
4364-
if (enable_ept) {
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vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK,PFERR_PRESENT_MASK);
4366-
vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH,PFERR_PRESENT_MASK);
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}
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}
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staticvoidvmx_vcpu_reset(structkvm_vcpu*vcpu,boolinit_event)

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