From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> Handle KVM hypercall for TDX according to TDX Guest-Host Communication Interface (GHCI) specification. The TDX GHCI specification defines the ABI for the guest TD to issue hypercalls. When R10 is non-zero, it indicates the TDG.VP.VMCALL is vendor-specific. KVM uses R10 as KVM hypercall number and R11-R14 as 4 arguments, while the error code is returned in R10. Follow the ABI and handle the KVM hypercall for TDX. Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> Co-developed-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx> Signed-off-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx> --- Hypercalls exit to userspace breakout: - Renamed from "KVM: TDX: handle KVM hypercall with TDG.VP.VMCALL" to "KVM: TDX: Handle KVM hypercall with TDG.VP.VMCALL". - Update the change log. - Rebased on Sean's "Prep KVM hypercall handling for TDX" patch set. https://lore.kernel.org/kvm/20241128004344.4072099-1-seanjc@xxxxxxxxxx - Use the right register (i.e. R10) to set the return code after returning back from userspace. --- arch/x86/kvm/vmx/tdx.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 19fd8a5dabd0..4cc55b120ab0 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -957,8 +957,39 @@ static int tdx_handle_triple_fault(struct kvm_vcpu *vcpu) return 0; } + +static int complete_hypercall_exit(struct kvm_vcpu *vcpu) +{ + kvm_r10_write(vcpu, vcpu->run->hypercall.ret); + return 1; +} + +static int tdx_emulate_vmcall(struct kvm_vcpu *vcpu) +{ + int r; + + /* + * ABI for KVM tdvmcall argument: + * In Guest-Hypervisor Communication Interface(GHCI) specification, + * Non-zero leaf number (R10 != 0) is defined to indicate + * vendor-specific. KVM uses this for KVM hypercall. NOTE: KVM + * hypercall number starts from one. Zero isn't used for KVM hypercall + * number. + * + * R10: KVM hypercall number + * arguments: R11, R12, R13, R14. + */ + r = __kvm_emulate_hypercall(vcpu, r10, r11, r12, r13, r14, true, 0, + complete_hypercall_exit); + + return r > 0; +} + static int handle_tdvmcall(struct kvm_vcpu *vcpu) { + if (tdvmcall_exit_type(vcpu)) + return tdx_emulate_vmcall(vcpu); + switch (tdvmcall_leaf(vcpu)) { default: break; -- 2.46.0
