On Fri, 2022-03-04 at 11:49 -0800, isaku.yamahata@intel.com wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> The TDX module specification defines TDG.VP.VMCALL API (TDVMCALL for short)
> for the guest TD to call hypercall to VMM. When the guest TD issues
> TDG.VP.VMCALL, the guest TD exits to VMM with a new exit reason of
> TDVMCALL. The arguments from the guest TD and returned values from the VMM
> are passed in the guest registers. The guest RCX registers indicates which
> registers are used.
>
> Define the TDVMCALL exit reason, which is carved out from the VMX exit
> reason namespace as the TDVMCALL exit from TDX guest to TDX-SEAM is really
> just a VM-Exit. Add a place holder to handle TDVMCALL exit.
>
> Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/include/uapi/asm/vmx.h | 4 +++-
> arch/x86/kvm/vmx/tdx.c | 27 ++++++++++++++++++++++++++-
> arch/x86/kvm/vmx/tdx.h | 13 +++++++++++++
> 3 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
> index 3d9b4598e166..cb0a0565219a 100644
> --- a/arch/x86/include/uapi/asm/vmx.h
> +++ b/arch/x86/include/uapi/asm/vmx.h
> @@ -92,6 +92,7 @@
> #define EXIT_REASON_UMWAIT 67
> #define EXIT_REASON_TPAUSE 68
> #define EXIT_REASON_BUS_LOCK 74
> +#define EXIT_REASON_TDCALL 77
>
> #define VMX_EXIT_REASONS \
> { EXIT_REASON_EXCEPTION_NMI, "EXCEPTION_NMI" }, \
> @@ -154,7 +155,8 @@
> { EXIT_REASON_XRSTORS, "XRSTORS" }, \
> { EXIT_REASON_UMWAIT, "UMWAIT" }, \
> { EXIT_REASON_TPAUSE, "TPAUSE" }, \
> - { EXIT_REASON_BUS_LOCK, "BUS_LOCK" }
> + { EXIT_REASON_BUS_LOCK, "BUS_LOCK" }, \
> + { EXIT_REASON_TDCALL, "TDCALL" }
>
> #define VMX_EXIT_REASON_FLAGS \
> { VMX_EXIT_REASONS_FAILED_VMENTRY, "FAILED_VMENTRY" }
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 8695836ce796..86daafd9eec0 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -780,7 +780,8 @@ static noinstr void tdx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
> struct vcpu_tdx *tdx)
> {
> guest_enter_irqoff();
> - tdx->exit_reason.full = __tdx_vcpu_run(tdx->tdvpr.pa, vcpu->arch.regs, 0);
> + tdx->exit_reason.full = __tdx_vcpu_run(tdx->tdvpr.pa, vcpu->arch.regs,
> + tdx->tdvmcall.regs_mask);
> guest_exit_irqoff();
> }
>
> @@ -815,6 +816,11 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu)
>
> if (tdx->exit_reason.error || tdx->exit_reason.non_recoverable)
> return EXIT_FASTPATH_NONE;
> +
> + if (tdx->exit_reason.basic == EXIT_REASON_TDCALL)
> + tdx->tdvmcall.rcx = vcpu->arch.regs[VCPU_REGS_RCX];
> + else
> + tdx->tdvmcall.rcx = 0;
> return EXIT_FASTPATH_NONE;
> }
>
> @@ -859,6 +865,23 @@ static int tdx_handle_triple_fault(struct kvm_vcpu *vcpu)
> return 0;
> }
>
> +static int handle_tdvmcall(struct kvm_vcpu *vcpu)
> +{
> + struct vcpu_tdx *tdx = to_tdx(vcpu);
> +
> + if (unlikely(tdx->tdvmcall.xmm_mask))
> + goto unsupported;
Put a comment explaining this logic?
> +
> + switch (tdvmcall_exit_reason(vcpu)) {
Could we rename tdxvmcall_exit_reason() to something like tdvmcall_leaf()?
Btw, why couldn't we merge previous patch to this one, so we don't have to look
back and forth to figure out exactly what do those functions do?
> + default:
> + break;
> + }
> +
> +unsupported:
> + tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_INVALID_OPERAND);
> + return 1;
> +}
> +
> void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int pgd_level)
> {
> td_vmcs_write64(to_tdx(vcpu), SHARED_EPT_POINTER, root_hpa & PAGE_MASK);
> @@ -1187,6 +1210,8 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
> return tdx_handle_exception(vcpu);
> case EXIT_REASON_EXTERNAL_INTERRUPT:
> return tdx_handle_external_interrupt(vcpu);
> + case EXIT_REASON_TDCALL:
> + return handle_tdvmcall(vcpu);
> case EXIT_REASON_EPT_VIOLATION:
> return tdx_handle_ept_violation(vcpu);
> case EXIT_REASON_EPT_MISCONFIG:
> diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
> index 7cd81780f3fa..9e8ed9b3119e 100644
> --- a/arch/x86/kvm/vmx/tdx.h
> +++ b/arch/x86/kvm/vmx/tdx.h
> @@ -86,6 +86,19 @@ struct vcpu_tdx {
> /* Posted interrupt descriptor */
> struct pi_desc pi_desc;
>
> + union {
> + struct {
> + union {
> + struct {
> + u16 gpr_mask;
> + u16 xmm_mask;
> + };
> + u32 regs_mask;
> + };
> + u32 reserved;
> + };
> + u64 rcx;
> + } tdvmcall;
> union tdx_exit_reason exit_reason;
>
> bool initialized;