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    Subject[PATCH v9 087/105] KVM: TDX: handle ept violation/misconfig exit
    Date
    From: Isaku Yamahata <isaku.yamahata@intel.com>

    On EPT violation, call a common function, __vmx_handle_ept_violation() to
    trigger x86 MMU code. On EPT misconfiguration, exit to ring 3 with
    KVM_EXIT_UNKNOWN. because EPT misconfiguration can't happen as MMIO is
    trigged by TDG.VP.VMCALL. No point to set a misconfiguration value for the
    fast path.

    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    ---
    arch/x86/kvm/vmx/tdx.c | 46 ++++++++++++++++++++++++++++++++++++++++++
    1 file changed, 46 insertions(+)

    diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
    index fbf7968bf718..def8eb3df75f 100644
    --- a/arch/x86/kvm/vmx/tdx.c
    +++ b/arch/x86/kvm/vmx/tdx.c
    @@ -1015,6 +1015,48 @@ void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
    __vmx_deliver_posted_interrupt(vcpu, &tdx->pi_desc, vector);
    }

    +static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu)
    +{
    + unsigned long exit_qual;
    +
    + if (kvm_is_private_gpa(vcpu->kvm, tdexit_gpa(vcpu))) {
    + /*
    + * Always treat SEPT violations as write faults. Ignore the
    + * EXIT_QUALIFICATION reported by TDX-SEAM for SEPT violations.
    + * TD private pages are always RWX in the SEPT tables,
    + * i.e. they're always mapped writable. Just as importantly,
    + * treating SEPT violations as write faults is necessary to
    + * avoid COW allocations, which will cause TDAUGPAGE failures
    + * due to aliasing a single HPA to multiple GPAs.
    + */
    +#define TDX_SEPT_VIOLATION_EXIT_QUAL EPT_VIOLATION_ACC_WRITE
    + exit_qual = TDX_SEPT_VIOLATION_EXIT_QUAL;
    + } else {
    + exit_qual = tdexit_exit_qual(vcpu);
    + if (exit_qual & EPT_VIOLATION_ACC_INSTR) {
    + pr_warn("kvm: TDX instr fetch to shared GPA = 0x%lx @ RIP = 0x%lx\n",
    + tdexit_gpa(vcpu), kvm_rip_read(vcpu));
    + vcpu->run->exit_reason = KVM_EXIT_EXCEPTION;
    + vcpu->run->ex.exception = PF_VECTOR;
    + vcpu->run->ex.error_code = exit_qual;
    + return 0;
    + }
    + }
    +
    + trace_kvm_page_fault(tdexit_gpa(vcpu), exit_qual);
    + return __vmx_handle_ept_violation(vcpu, tdexit_gpa(vcpu), exit_qual);
    +}
    +
    +static int tdx_handle_ept_misconfig(struct kvm_vcpu *vcpu)
    +{
    + WARN_ON_ONCE(1);
    +
    + vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
    + vcpu->run->hw.hardware_exit_reason = EXIT_REASON_EPT_MISCONFIG;
    +
    + return 0;
    +}
    +
    int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
    {
    union tdx_exit_reason exit_reason = to_tdx(vcpu)->exit_reason;
    @@ -1037,6 +1079,10 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
    WARN_ON_ONCE(fastpath != EXIT_FASTPATH_NONE);

    switch (exit_reason.basic) {
    + case EXIT_REASON_EPT_VIOLATION:
    + return tdx_handle_ept_violation(vcpu);
    + case EXIT_REASON_EPT_MISCONFIG:
    + return tdx_handle_ept_misconfig(vcpu);
    case EXIT_REASON_OTHER_SMI:
    /*
    * If reach here, it's not a Machine Check System Management
    --
    2.25.1
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