On Fri, Mar 4, 2022 at 12:00 PM <isaku.yamahata@xxxxxxxxx> wrote:
>
> From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
>
> 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 <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 4 +++
> arch/x86/kvm/x86.c | 54 ++++++++++++++++++++-------------
> 2 files changed, 37 insertions(+), 21 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 8dab9f16f559..33b75b0e3de1 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1818,6 +1818,10 @@ void kvm_request_apicv_update(struct kvm *kvm, bool activate,
> void __kvm_request_apicv_update(struct kvm *kvm, bool activate,
> unsigned long bit);
>
> +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 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 314ae43e07bf..9acb33a17445 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9090,26 +9090,15 @@ 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)
> {
> - 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;
> @@ -9118,11 +9107,6 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
> a3 &= 0xFFFFFFFF;
> }
>
> - if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
> - ret = -KVM_EPERM;
> - goto out;
> - }
> -
> ret = -KVM_ENOSYS;
>
> switch (nr) {
> @@ -9181,6 +9165,34 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
> ret = -KVM_ENOSYS;
> break;
> }
> + 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;
> +
> + 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_mode(vcpu);
I think this should be "op_64_bit = is_64_bit_hypercall(vcpu);"
is_64_bit_mode was replaced with is_64_bit_hypercall to support
protected guests here:
https://lore.kernel.org/all/87cztf8h43.fsf@xxxxxxxxxxxxxxxxxxxx/T/
Without it, op_64_bit will be set to 0 for TD VMs which will cause the
upper 32 bit of the registers to be cleared in __kvm_emulate_hypercall
> +
> + if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
> + ret = -KVM_EPERM;
> + goto out;
> + }
> +
> + ret = __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit);
> out:
> if (!op_64_bit)
> ret = (u32)ret;
> --
> 2.25.1
>
Sagi
