Re: [RFC PATCH v5 084/104] KVM: TDX: Add a place holder to handle TDX VM exit

[Paolo Bonzini <pbonzini@redhat.com>]

On 3/4/22 20:49, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
> 
> Wire up handle_exit and handle_exit_irqoff methods and add a place holder
> to handle VM exit.  Add helper functions to get exit info, exit
> qualification, etc.
> 
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
>   arch/x86/kvm/vmx/main.c    | 35 +++++++++++++++--
>   arch/x86/kvm/vmx/tdx.c     | 79 ++++++++++++++++++++++++++++++++++++++
>   arch/x86/kvm/vmx/x86_ops.h | 11 ++++++
>   3 files changed, 122 insertions(+), 3 deletions(-)

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index aa84c13f8ee1..1e65406e3882 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -148,6 +148,23 @@ static void vt_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>   	return vmx_vcpu_load(vcpu, cpu);
>   }
>   
> +static int vt_handle_exit(struct kvm_vcpu *vcpu,
> +			     enum exit_fastpath_completion fastpath)
> +{
> +	if (is_td_vcpu(vcpu))
> +		return tdx_handle_exit(vcpu, fastpath);
> +
> +	return vmx_handle_exit(vcpu, fastpath);
> +}
> +
> +static void vt_handle_exit_irqoff(struct kvm_vcpu *vcpu)
> +{
> +	if (is_td_vcpu(vcpu))
> +		return tdx_handle_exit_irqoff(vcpu);
> +
> +	vmx_handle_exit_irqoff(vcpu);
> +}
> +
>   static void vt_apicv_post_state_restore(struct kvm_vcpu *vcpu)
>   {
>   	if (is_td_vcpu(vcpu))
> @@ -340,6 +357,18 @@ static void vt_request_immediate_exit(struct kvm_vcpu *vcpu)
>   	vmx_request_immediate_exit(vcpu);
>   }
>   
> +static void vt_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
> +			u64 *info1, u64 *info2, u32 *intr_info, u32 *error_code)
> +{
> +	if (is_td_vcpu(vcpu)) {
> +		tdx_get_exit_info(vcpu, reason, info1, info2, intr_info,
> +				error_code);
> +		return;
> +	}
> +
> +	vmx_get_exit_info(vcpu, reason, info1, info2, intr_info, error_code);
> +}
> +
>   static int vt_mem_enc_op(struct kvm *kvm, void __user *argp)
>   {
>   	if (!is_td(kvm))
> @@ -411,7 +440,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
>   
>   	.vcpu_pre_run = vmx_vcpu_pre_run,
>   	.run = vt_vcpu_run,
> -	.handle_exit = vmx_handle_exit,
> +	.handle_exit = vt_handle_exit,
>   	.skip_emulated_instruction = vmx_skip_emulated_instruction,
>   	.update_emulated_instruction = vmx_update_emulated_instruction,
>   	.set_interrupt_shadow = vt_set_interrupt_shadow,
> @@ -446,7 +475,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
>   	.set_identity_map_addr = vmx_set_identity_map_addr,
>   	.get_mt_mask = vmx_get_mt_mask,
>   
> -	.get_exit_info = vmx_get_exit_info,
> +	.get_exit_info = vt_get_exit_info,
>   
>   	.vcpu_after_set_cpuid = vmx_vcpu_after_set_cpuid,
>   
> @@ -460,7 +489,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
>   	.load_mmu_pgd = vt_load_mmu_pgd,
>   
>   	.check_intercept = vmx_check_intercept,
> -	.handle_exit_irqoff = vmx_handle_exit_irqoff,
> +	.handle_exit_irqoff = vt_handle_exit_irqoff,
>   
>   	.request_immediate_exit = vt_request_immediate_exit,
>   
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 273898de9f7a..155208a8d768 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -68,6 +68,26 @@ static __always_inline hpa_t set_hkid_to_hpa(hpa_t pa, u16 hkid)
>   	return pa;
>   }
>   
> +static __always_inline unsigned long tdexit_exit_qual(struct kvm_vcpu *vcpu)
> +{
> +	return kvm_rcx_read(vcpu);
> +}
> +
> +static __always_inline unsigned long tdexit_ext_exit_qual(struct kvm_vcpu *vcpu)
> +{
> +	return kvm_rdx_read(vcpu);
> +}
> +
> +static __always_inline unsigned long tdexit_gpa(struct kvm_vcpu *vcpu)
> +{
> +	return kvm_r8_read(vcpu);
> +}
> +
> +static __always_inline unsigned long tdexit_intr_info(struct kvm_vcpu *vcpu)
> +{
> +	return kvm_r9_read(vcpu);
> +}
> +
>   static inline bool is_td_vcpu_created(struct vcpu_tdx *tdx)
>   {
>   	return tdx->tdvpr.added;
> @@ -768,6 +788,25 @@ void tdx_inject_nmi(struct kvm_vcpu *vcpu)
>   	td_management_write8(to_tdx(vcpu), TD_VCPU_PEND_NMI, 1);
>   }
>   
> +void tdx_handle_exit_irqoff(struct kvm_vcpu *vcpu)
> +{
> +	struct vcpu_tdx *tdx = to_tdx(vcpu);
> +	u16 exit_reason = tdx->exit_reason.basic;
> +
> +	if (exit_reason == EXIT_REASON_EXCEPTION_NMI)
> +		vmx_handle_exception_nmi_irqoff(vcpu, tdexit_intr_info(vcpu));
> +	else if (exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT)
> +		vmx_handle_external_interrupt_irqoff(vcpu,
> +						     tdexit_intr_info(vcpu));
> +}
> +
> +static int tdx_handle_triple_fault(struct kvm_vcpu *vcpu)
> +{
> +	vcpu->run->exit_reason = KVM_EXIT_SHUTDOWN;
> +	vcpu->mmio_needed = 0;
> +	return 0;
> +}
> +
>   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);
> @@ -1042,6 +1081,46 @@ void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
>   	__vmx_deliver_posted_interrupt(vcpu, &tdx->pi_desc, vector);
>   }
>   
> +int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
> +{
> +	union tdx_exit_reason exit_reason = to_tdx(vcpu)->exit_reason;
> +
> +	if (unlikely(exit_reason.non_recoverable || exit_reason.error)) {
> +		if (exit_reason.basic == EXIT_REASON_TRIPLE_FAULT)
> +			return tdx_handle_triple_fault(vcpu);
> +
> +		kvm_pr_unimpl("TD exit 0x%llx, %d\n",
> +			exit_reason.full, exit_reason.basic);
> +		goto unhandled_exit;
> +	}
> +
> +	WARN_ON_ONCE(fastpath != EXIT_FASTPATH_NONE);
> +
> +	switch (exit_reason.basic) {
> +	default:
> +		break;
> +	}
> +
> +unhandled_exit:
> +	vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
> +	vcpu->run->hw.hardware_exit_reason = exit_reason.full;
> +	return 0;
> +}
> +
> +void tdx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
> +		u64 *info1, u64 *info2, u32 *intr_info, u32 *error_code)
> +{
> +	struct vcpu_tdx *tdx = to_tdx(vcpu);
> +
> +	*reason = tdx->exit_reason.full;
> +
> +	*info1 = tdexit_exit_qual(vcpu);
> +	*info2 = tdexit_ext_exit_qual(vcpu);
> +
> +	*intr_info = tdexit_intr_info(vcpu);
> +	*error_code = 0;
> +}
> +
>   static int tdx_capabilities(struct kvm *kvm, struct kvm_tdx_cmd *cmd)
>   {
>   	struct kvm_tdx_capabilities __user *user_caps;
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index 31be5e8a1d5c..c0a34186bc37 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -146,11 +146,16 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu);
>   void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu);
>   void tdx_vcpu_put(struct kvm_vcpu *vcpu);
>   void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
> +void tdx_handle_exit_irqoff(struct kvm_vcpu *vcpu);
> +int tdx_handle_exit(struct kvm_vcpu *vcpu,
> +		enum exit_fastpath_completion fastpath);
>   
>   void tdx_apicv_post_state_restore(struct kvm_vcpu *vcpu);
>   void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
>   			   int trig_mode, int vector);
>   void tdx_inject_nmi(struct kvm_vcpu *vcpu);
> +void tdx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
> +		u64 *info1, u64 *info2, u32 *intr_info, u32 *error_code);
>   
>   int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
>   int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
> @@ -177,11 +182,17 @@ static inline fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) { return EXIT_FASTP
>   static inline void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) {}
>   static inline void tdx_vcpu_put(struct kvm_vcpu *vcpu) {}
>   static inline void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) {}
> +static inline void tdx_handle_exit_irqoff(struct kvm_vcpu *vcpu) {}
> +static inline int tdx_handle_exit(struct kvm_vcpu *vcpu,
> +		enum exit_fastpath_completion fastpath) { return 0; }
>   
>   static inline void tdx_apicv_post_state_restore(struct kvm_vcpu *vcpu) {}
>   static inline void tdx_deliver_interrupt(
>   	struct kvm_lapic *apic, int delivery_mode, int trig_mode, int vector) {}
>   static inline void tdx_inject_nmi(struct kvm_vcpu *vcpu) {}
> +static inline void tdx_get_exit_info(
> +	struct kvm_vcpu *vcpu, u32 *reason, u64 *info1, u64 *info2,
> +	u32 *intr_info, u32 *error_code) {}
>   
>   static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
>   static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }