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    Subject[PATCH 01/21] KVM: x86: Split core of hypercall emulation to helper function
    Date
    From: Sean Christopherson <seanjc@google.com>

    By necessity, TDX will use a different register ABI for hypercalls.
    Break out the core functionality so that it may be reused for TDX.

    Signed-off-by: Sean Christopherson <seanjc@google.com>
    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    Message-Id: <5134caa55ac3dec33fb2addb5545b52b3b52db02.1705965635.git.isaku.yamahata@intel.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    ---
    arch/x86/include/asm/kvm_host.h | 4 +++
    arch/x86/kvm/x86.c | 56 ++++++++++++++++++++++-----------
    2 files changed, 42 insertions(+), 18 deletions(-)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index 724a0c778f79..85dc0f7d09e3 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -2133,6 +2133,10 @@ static inline void kvm_clear_apicv_inhibit(struct kvm *kvm,
    kvm_set_or_clear_apicv_inhibit(kvm, reason, false);
    }

    +unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
    + unsigned long a0, unsigned long a1,
    + unsigned long a2, unsigned long a3,
    + int op_64_bit, int cpl);
    int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);

    int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index b9dfe3179332..f10a5a617120 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -10046,26 +10046,15 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu)
    return kvm_skip_emulated_instruction(vcpu);
    }

    -int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
    +unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
    + unsigned long a0, unsigned long a1,
    + unsigned long a2, unsigned long a3,
    + int op_64_bit, int cpl)
    {
    - unsigned long nr, a0, a1, a2, a3, ret;
    - int op_64_bit;
    -
    - if (kvm_xen_hypercall_enabled(vcpu->kvm))
    - return kvm_xen_hypercall(vcpu);
    -
    - if (kvm_hv_hypercall_enabled(vcpu))
    - return kvm_hv_hypercall(vcpu);
    -
    - nr = kvm_rax_read(vcpu);
    - a0 = kvm_rbx_read(vcpu);
    - a1 = kvm_rcx_read(vcpu);
    - a2 = kvm_rdx_read(vcpu);
    - a3 = kvm_rsi_read(vcpu);
    + unsigned long ret;

    trace_kvm_hypercall(nr, a0, a1, a2, a3);

    - op_64_bit = is_64_bit_hypercall(vcpu);
    if (!op_64_bit) {
    nr &= 0xFFFFFFFF;
    a0 &= 0xFFFFFFFF;
    @@ -10074,7 +10063,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
    a3 &= 0xFFFFFFFF;
    }

    - if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
    + if (cpl) {
    ret = -KVM_EPERM;
    goto out;
    }
    @@ -10135,18 +10124,49 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)

    WARN_ON_ONCE(vcpu->run->hypercall.flags & KVM_EXIT_HYPERCALL_MBZ);
    vcpu->arch.complete_userspace_io = complete_hypercall_exit;
    + /* stat is incremented on completion. */
    return 0;
    }
    default:
    ret = -KVM_ENOSYS;
    break;
    }
    +
    out:
    + ++vcpu->stat.hypercalls;
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(__kvm_emulate_hypercall);
    +
    +int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
    +{
    + unsigned long nr, a0, a1, a2, a3, ret;
    + int op_64_bit;
    + int cpl;
    +
    + if (kvm_xen_hypercall_enabled(vcpu->kvm))
    + return kvm_xen_hypercall(vcpu);
    +
    + if (kvm_hv_hypercall_enabled(vcpu))
    + return kvm_hv_hypercall(vcpu);
    +
    + nr = kvm_rax_read(vcpu);
    + a0 = kvm_rbx_read(vcpu);
    + a1 = kvm_rcx_read(vcpu);
    + a2 = kvm_rdx_read(vcpu);
    + a3 = kvm_rsi_read(vcpu);
    + op_64_bit = is_64_bit_hypercall(vcpu);
    + cpl = static_call(kvm_x86_get_cpl)(vcpu);
    +
    + ret = __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit, cpl);
    + if (nr == KVM_HC_MAP_GPA_RANGE && !ret)
    + /* MAP_GPA tosses the request to the user space. */
    + return 0;
    +
    if (!op_64_bit)
    ret = (u32)ret;
    kvm_rax_write(vcpu, ret);

    - ++vcpu->stat.hypercalls;
    return kvm_skip_emulated_instruction(vcpu);
    }
    EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);
    --
    2.39.0


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