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    Subject[RFC PATCH v5 094/104] KVM: TDX: Handle TDX PV MMIO hypercall
    Date
    From: Sean Christopherson <sean.j.christopherson@intel.com>

    Export kvm_io_bus_read and kvm_mmio tracepoint and wire up TDX PV MMIO
    hypercall to the KVM backend functions.

    kvm_io_bus_read/write() searches KVM device emulated in kernel of the given
    MMIO address and emulates the MMIO. As TDX PV MMIO also needs it, export
    kvm_io_bus_read(). kvm_io_bus_write() is already exported. TDX PV MMIO
    emulates some of MMIO itself. To add trace point consistently with x86
    kvm, export kvm_mmio tracepoint.

    Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    ---
    arch/x86/kvm/vmx/tdx.c | 114 +++++++++++++++++++++++++++++++++++++++++
    arch/x86/kvm/x86.c | 1 +
    virt/kvm/kvm_main.c | 2 +
    3 files changed, 117 insertions(+)

    diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
    index c900347d0bc7..914af5da4805 100644
    --- a/arch/x86/kvm/vmx/tdx.c
    +++ b/arch/x86/kvm/vmx/tdx.c
    @@ -1012,6 +1012,118 @@ static int tdx_emulate_io(struct kvm_vcpu *vcpu)
    return ret;
    }

    +static int tdx_complete_mmio(struct kvm_vcpu *vcpu)
    +{
    + unsigned long val = 0;
    + gpa_t gpa;
    + int size;
    +
    + WARN_ON(vcpu->mmio_needed != 1);
    + vcpu->mmio_needed = 0;
    +
    + if (!vcpu->mmio_is_write) {
    + gpa = vcpu->mmio_fragments[0].gpa;
    + size = vcpu->mmio_fragments[0].len;
    +
    + memcpy(&val, vcpu->run->mmio.data, size);
    + tdvmcall_set_return_val(vcpu, val);
    + trace_kvm_mmio(KVM_TRACE_MMIO_READ, size, gpa, &val);
    + }
    + return 1;
    +}
    +
    +static inline int tdx_mmio_write(struct kvm_vcpu *vcpu, gpa_t gpa, int size,
    + unsigned long val)
    +{
    + if (kvm_iodevice_write(vcpu, &vcpu->arch.apic->dev, gpa, size, &val) &&
    + kvm_io_bus_write(vcpu, KVM_MMIO_BUS, gpa, size, &val))
    + return -EOPNOTSUPP;
    +
    + trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, size, gpa, &val);
    + return 0;
    +}
    +
    +static inline int tdx_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, int size)
    +{
    + unsigned long val;
    +
    + if (kvm_iodevice_read(vcpu, &vcpu->arch.apic->dev, gpa, size, &val) &&
    + kvm_io_bus_read(vcpu, KVM_MMIO_BUS, gpa, size, &val))
    + return -EOPNOTSUPP;
    +
    + tdvmcall_set_return_val(vcpu, val);
    + trace_kvm_mmio(KVM_TRACE_MMIO_READ, size, gpa, &val);
    + return 0;
    +}
    +
    +static int tdx_emulate_mmio(struct kvm_vcpu *vcpu)
    +{
    + struct kvm_memory_slot *slot;
    + int size, write, r;
    + unsigned long val;
    + gpa_t gpa;
    +
    + WARN_ON(vcpu->mmio_needed);
    +
    + size = tdvmcall_p1_read(vcpu);
    + write = tdvmcall_p2_read(vcpu);
    + gpa = tdvmcall_p3_read(vcpu);
    + val = write ? tdvmcall_p4_read(vcpu) : 0;
    +
    + if (size != 1 && size != 2 && size != 4 && size != 8)
    + goto error;
    + if (write != 0 && write != 1)
    + goto error;
    +
    + /* Strip the shared bit, allow MMIO with and without it set. */
    + gpa = kvm_gpa_unalias(vcpu->kvm, gpa);
    +
    + if (size > 8u || ((gpa + size - 1) ^ gpa) & PAGE_MASK)
    + goto error;
    +
    + slot = kvm_vcpu_gfn_to_memslot(vcpu, gpa_to_gfn(gpa));
    + if (slot && !(slot->flags & KVM_MEMSLOT_INVALID))
    + goto error;
    +
    + if (!kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) {
    + trace_kvm_fast_mmio(gpa);
    + return 1;
    + }
    +
    + if (write)
    + r = tdx_mmio_write(vcpu, gpa, size, val);
    + else
    + r = tdx_mmio_read(vcpu, gpa, size);
    + if (!r) {
    + /* Kernel completed device emulation. */
    + tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_SUCCESS);
    + return 1;
    + }
    +
    + /* Request the device emulation to userspace device model. */
    + vcpu->mmio_needed = 1;
    + vcpu->mmio_is_write = write;
    + vcpu->arch.complete_userspace_io = tdx_complete_mmio;
    +
    + vcpu->run->mmio.phys_addr = gpa;
    + vcpu->run->mmio.len = size;
    + vcpu->run->mmio.is_write = write;
    + vcpu->run->exit_reason = KVM_EXIT_MMIO;
    +
    + if (write) {
    + memcpy(vcpu->run->mmio.data, &val, size);
    + } else {
    + vcpu->mmio_fragments[0].gpa = gpa;
    + vcpu->mmio_fragments[0].len = size;
    + trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, size, gpa, NULL);
    + }
    + return 0;
    +
    +error:
    + tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_SUCCESS);
    + return 1;
    +}
    +
    static int handle_tdvmcall(struct kvm_vcpu *vcpu)
    {
    struct vcpu_tdx *tdx = to_tdx(vcpu);
    @@ -1029,6 +1141,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
    return tdx_emulate_hlt(vcpu);
    case EXIT_REASON_IO_INSTRUCTION:
    return tdx_emulate_io(vcpu);
    + case EXIT_REASON_EPT_VIOLATION:
    + return tdx_emulate_mmio(vcpu);
    default:
    break;
    }
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index 9acb33a17445..483fa46b1be7 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -12915,6 +12915,7 @@ bool kvm_arch_dirty_log_supported(struct kvm *kvm)

    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry);
    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
    +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_mmio);
    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_page_fault);
    diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    index d4e117f5b5b9..6db075db6098 100644
    --- a/virt/kvm/kvm_main.c
    +++ b/virt/kvm/kvm_main.c
    @@ -2259,6 +2259,7 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn

    return NULL;
    }
    +EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_memslot);

    bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
    {
    @@ -5126,6 +5127,7 @@ int kvm_io_bus_read(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
    r = __kvm_io_bus_read(vcpu, bus, &range, val);
    return r < 0 ? r : 0;
    }
    +EXPORT_SYMBOL_GPL(kvm_io_bus_read);

    /* Caller must hold slots_lock. */
    int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
    --
    2.25.1
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