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    Subject[PATCH v3 6/9] KVM: VMX: introduce vmx_need_pf_intercept
    Date
    From: Paolo Bonzini <pbonzini@redhat.com>

    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    ---
    arch/x86/kvm/vmx/nested.c | 28 +++++++++++++++++-----------
    arch/x86/kvm/vmx/vmx.c | 2 +-
    arch/x86/kvm/vmx/vmx.h | 5 +++++
    3 files changed, 23 insertions(+), 12 deletions(-)

    diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
    index b26655104d4a..1aea9e3b8c43 100644
    --- a/arch/x86/kvm/vmx/nested.c
    +++ b/arch/x86/kvm/vmx/nested.c
    @@ -2433,22 +2433,28 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)

    /*
    * Whether page-faults are trapped is determined by a combination of
    - * 3 settings: PFEC_MASK, PFEC_MATCH and EXCEPTION_BITMAP.PF.
    - * If enable_ept, L0 doesn't care about page faults and we should
    - * set all of these to L1's desires. However, if !enable_ept, L0 does
    - * care about (at least some) page faults, and because it is not easy
    - * (if at all possible?) to merge L0 and L1's desires, we simply ask
    - * to exit on each and every L2 page fault. This is done by setting
    - * MASK=MATCH=0 and (see below) EB.PF=1.
    + * 3 settings: PFEC_MASK, PFEC_MATCH and EXCEPTION_BITMAP.PF. If L0
    + * doesn't care about page faults then we should set all of these to
    + * L1's desires. However, if L0 does care about (some) page faults, it
    + * is not easy (if at all possible?) to merge L0 and L1's desires, we
    + * simply ask to exit on each and every L2 page fault. This is done by
    + * setting MASK=MATCH=0 and (see below) EB.PF=1.
    * Note that below we don't need special code to set EB.PF beyond the
    * "or"ing of the EB of vmcs01 and vmcs12, because when enable_ept,
    * vmcs01's EB.PF is 0 so the "or" will take vmcs12's value, and when
    * !enable_ept, EB.PF is 1, so the "or" will always be 1.
    */
    - vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK,
    - enable_ept ? vmcs12->page_fault_error_code_mask : 0);
    - vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH,
    - enable_ept ? vmcs12->page_fault_error_code_match : 0);
    + if (vmx_need_pf_intercept(&vmx->vcpu)) {
    + /*
    + * TODO: if both L0 and L1 need the same MASK and MATCH,
    + * go ahead and use it?
    + */
    + vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, 0);
    + vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, 0);
    + } else {
    + vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, vmcs12->page_fault_error_code_mask);
    + vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, vmcs12->page_fault_error_code_match);
    + }

    if (cpu_has_vmx_apicv()) {
    vmcs_write64(EOI_EXIT_BITMAP0, vmcs12->eoi_exit_bitmap0);
    diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
    index 178ee92551a9..770b090969fb 100644
    --- a/arch/x86/kvm/vmx/vmx.c
    +++ b/arch/x86/kvm/vmx/vmx.c
    @@ -780,7 +780,7 @@ void update_exception_bitmap(struct kvm_vcpu *vcpu)
    eb |= 1u << BP_VECTOR;
    if (to_vmx(vcpu)->rmode.vm86_active)
    eb = ~0;
    - if (enable_ept)
    + if (!vmx_need_pf_intercept(vcpu))
    eb &= ~(1u << PF_VECTOR);

    /* When we are running a nested L2 guest and L1 specified for it a
    diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
    index 639798e4a6ca..b0e5e210f1c1 100644
    --- a/arch/x86/kvm/vmx/vmx.h
    +++ b/arch/x86/kvm/vmx/vmx.h
    @@ -550,6 +550,11 @@ static inline bool vmx_has_waitpkg(struct vcpu_vmx *vmx)
    SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE;
    }

    +static inline bool vmx_need_pf_intercept(struct kvm_vcpu *vcpu)
    +{
    + return !enable_ept;
    +}
    +
    void dump_vmcs(void);

    #endif /* __KVM_X86_VMX_H */
    --
    2.26.2
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