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. Morph the TDG.VP.VMCALL with KVM hypercall to EXIT_REASON_VMCALL and marshall r10~r14 from vp_enter_args to the appropriate x86 registers for KVM hypercall handling. 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 v3: - No change. Hypercalls exit to userspace v2: - Morph the TDG.VP.VMCALL with KVM hypercall to EXIT_REASON_VMCALL. - Marshall values to the appropriate x86 registers for KVM hypercall handling. Hypercalls exit to userspace v1: - 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 | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 7a5f375d976a..4f659ca50469 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -967,6 +967,23 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit) return tdx_exit_handlers_fastpath(vcpu); } +static int complete_hypercall_exit(struct kvm_vcpu *vcpu) +{ + tdvmcall_set_return_code(vcpu, vcpu->run->hypercall.ret); + return 1; +} + +static int tdx_emulate_vmcall(struct kvm_vcpu *vcpu) +{ + kvm_rax_write(vcpu, to_tdx(vcpu)->vp_enter_args.r10); + kvm_rbx_write(vcpu, to_tdx(vcpu)->vp_enter_args.r11); + kvm_rcx_write(vcpu, to_tdx(vcpu)->vp_enter_args.r12); + kvm_rdx_write(vcpu, to_tdx(vcpu)->vp_enter_args.r13); + kvm_rsi_write(vcpu, to_tdx(vcpu)->vp_enter_args.r14); + + return __kvm_emulate_hypercall(vcpu, 0, complete_hypercall_exit); +} + static int handle_tdvmcall(struct kvm_vcpu *vcpu) { switch (tdvmcall_leaf(vcpu)) { @@ -1338,6 +1355,8 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath) return 0; case EXIT_REASON_TDCALL: return handle_tdvmcall(vcpu); + case EXIT_REASON_VMCALL: + return tdx_emulate_vmcall(vcpu); default: break; } -- 2.46.0
