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Message-ID: <874ktetu3l.fsf@vitty.brq.redhat.com>
Date:   Mon, 20 Apr 2020 10:54:54 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH 3/3] KVM: x86: move nested-related kvm_x86_ops to a separate struct

Paolo Bonzini <pbonzini@...hat.com> writes:

> Clean up some of the patching of kvm_x86_ops, by moving kvm_x86_ops related to
> nested virtualization into a separate struct.
>
> As a result, these ops will always be non-NULL on VMX.  This is not a problem:
>
> * check_nested_events is only called if is_guest_mode(vcpu) returns true
>
> * get_nested_state treats VMXOFF state the same as nested being disabled
>
> * set_nested_state fails if you attempt to set nested state while
>   nesting is disabled
>
> * nested_enable_evmcs could already be called on a CPU without VMX enabled
>   in CPUID.
>
> * nested_get_evmcs_version was fixed in the previous patch
>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/include/asm/kvm_host.h | 29 ++++++++++++++++-------------
>  arch/x86/kvm/hyperv.c           |  4 ++--
>  arch/x86/kvm/svm/nested.c       |  6 +++++-
>  arch/x86/kvm/svm/svm.c          | 13 +++++--------
>  arch/x86/kvm/svm/svm.h          |  3 ++-
>  arch/x86/kvm/vmx/nested.c       | 16 +++++++++-------
>  arch/x86/kvm/vmx/nested.h       |  2 ++
>  arch/x86/kvm/vmx/vmx.c          |  7 +------
>  arch/x86/kvm/x86.c              | 28 ++++++++++++++--------------
>  9 files changed, 56 insertions(+), 52 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index fc38d95e28a4..ca0d0f9b3f92 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1178,7 +1178,6 @@ struct kvm_x86_ops {
>  			       struct x86_exception *exception);
>  	void (*handle_exit_irqoff)(struct kvm_vcpu *vcpu);
>  
> -	int (*check_nested_events)(struct kvm_vcpu *vcpu);
>  	void (*request_immediate_exit)(struct kvm_vcpu *vcpu);
>  
>  	void (*sched_in)(struct kvm_vcpu *kvm, int cpu);
> @@ -1211,6 +1210,7 @@ struct kvm_x86_ops {
>  
>  	/* pmu operations of sub-arch */
>  	const struct kvm_pmu_ops *pmu_ops;
> +	const struct kvm_x86_nested_ops *nested_ops;
>  
>  	/*
>  	 * Architecture specific hooks for vCPU blocking due to
> @@ -1238,14 +1238,6 @@ struct kvm_x86_ops {
>  
>  	void (*setup_mce)(struct kvm_vcpu *vcpu);
>  
> -	int (*get_nested_state)(struct kvm_vcpu *vcpu,
> -				struct kvm_nested_state __user *user_kvm_nested_state,
> -				unsigned user_data_size);
> -	int (*set_nested_state)(struct kvm_vcpu *vcpu,
> -				struct kvm_nested_state __user *user_kvm_nested_state,
> -				struct kvm_nested_state *kvm_state);
> -	bool (*get_vmcs12_pages)(struct kvm_vcpu *vcpu);
> -
>  	int (*smi_allowed)(struct kvm_vcpu *vcpu);
>  	int (*pre_enter_smm)(struct kvm_vcpu *vcpu, char *smstate);
>  	int (*pre_leave_smm)(struct kvm_vcpu *vcpu, const char *smstate);
> @@ -1257,16 +1249,27 @@ struct kvm_x86_ops {
>  
>  	int (*get_msr_feature)(struct kvm_msr_entry *entry);
>  
> -	int (*nested_enable_evmcs)(struct kvm_vcpu *vcpu,
> -				   uint16_t *vmcs_version);
> -	uint16_t (*nested_get_evmcs_version)(struct kvm_vcpu *vcpu);
> -
>  	bool (*need_emulation_on_page_fault)(struct kvm_vcpu *vcpu);
>  
>  	bool (*apic_init_signal_blocked)(struct kvm_vcpu *vcpu);
>  	int (*enable_direct_tlbflush)(struct kvm_vcpu *vcpu);
>  };
>  
> +struct kvm_x86_nested_ops {
> +	int (*check_nested_events)(struct kvm_vcpu *vcpu);
> +	int (*get_nested_state)(struct kvm_vcpu *vcpu,
> +				struct kvm_nested_state __user *user_kvm_nested_state,
> +				unsigned user_data_size);
> +	int (*set_nested_state)(struct kvm_vcpu *vcpu,
> +				struct kvm_nested_state __user *user_kvm_nested_state,
> +				struct kvm_nested_state *kvm_state);
> +	bool (*get_vmcs12_pages)(struct kvm_vcpu *vcpu);
> +
> +	int (*nested_enable_evmcs)(struct kvm_vcpu *vcpu,
> +				   uint16_t *vmcs_version);
> +	uint16_t (*nested_get_evmcs_version)(struct kvm_vcpu *vcpu);

I think that 'nested' becomes superfluous within 'struct
kvm_x86_nested_ops'.

Like
  kvm_x86_ops.nested_ops->nested_get_evmcs_version(vcpu);
vs
  kvm_x86_ops.nested_ops->get_evmcs_version(vcpu);


> +};
> +
>  struct kvm_x86_init_ops {
>  	int (*cpu_has_kvm_support)(void);
>  	int (*disabled_by_bios)(void);
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index b850f676abe4..d1a0f9294d57 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -1799,8 +1799,8 @@ int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
>  	};
>  	int i, nent = ARRAY_SIZE(cpuid_entries);
>  
> -	if (kvm_x86_ops.nested_get_evmcs_version)
> -		evmcs_ver = kvm_x86_ops.nested_get_evmcs_version(vcpu);
> +	if (kvm_x86_ops.nested_ops->nested_get_evmcs_version)
> +		evmcs_ver = kvm_x86_ops.nested_ops->nested_get_evmcs_version(vcpu);
>  
>  	/* Skip NESTED_FEATURES if eVMCS is not supported */
>  	if (!evmcs_ver)
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 3e5bd739a6f6..671b883fd14e 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -784,7 +784,7 @@ static bool nested_exit_on_intr(struct vcpu_svm *svm)
>  	return (svm->nested.intercept & 1ULL);
>  }
>  
> -int svm_check_nested_events(struct kvm_vcpu *vcpu)
> +static int svm_check_nested_events(struct kvm_vcpu *vcpu)
>  {
>  	struct vcpu_svm *svm = to_svm(vcpu);
>  	bool block_nested_events =
> @@ -825,3 +825,7 @@ int nested_svm_exit_special(struct vcpu_svm *svm)
>  
>  	return NESTED_EXIT_CONTINUE;
>  }
> +
> +struct kvm_x86_nested_ops svm_nested_ops = {
> +	.check_nested_events = svm_check_nested_events,
> +};
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index a6f4e1bdb045..a91e397d6750 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3895,9 +3895,9 @@ static bool svm_apic_init_signal_blocked(struct kvm_vcpu *vcpu)
>  	/*
>  	 * TODO: Last condition latch INIT signals on vCPU when
>  	 * vCPU is in guest-mode and vmcb12 defines intercept on INIT.
> -	 * To properly emulate the INIT intercept, SVM should implement
> -	 * kvm_x86_ops.check_nested_events() and call nested_svm_vmexit()
> -	 * there if an INIT signal is pending.
> +	 * To properly emulate the INIT intercept,
> +	 * svm_check_nested_events() should call nested_svm_vmexit()
> +	 * if an INIT signal is pending.
>  	 */
>  	return !gif_set(svm) ||
>  		   (svm->vmcb->control.intercept & (1ULL << INTERCEPT_INIT));
> @@ -4025,6 +4025,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
>  	.sched_in = svm_sched_in,
>  
>  	.pmu_ops = &amd_pmu_ops,
> +	.nested_ops = &svm_nested_ops,
> +
>  	.deliver_posted_interrupt = svm_deliver_avic_intr,
>  	.dy_apicv_has_pending_interrupt = svm_dy_apicv_has_pending_interrupt,
>  	.update_pi_irte = svm_update_pi_irte,
> @@ -4039,14 +4041,9 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
>  	.mem_enc_reg_region = svm_register_enc_region,
>  	.mem_enc_unreg_region = svm_unregister_enc_region,
>  
> -	.nested_enable_evmcs = NULL,
> -	.nested_get_evmcs_version = NULL,
> -
>  	.need_emulation_on_page_fault = svm_need_emulation_on_page_fault,
>  
>  	.apic_init_signal_blocked = svm_apic_init_signal_blocked,
> -
> -	.check_nested_events = svm_check_nested_events,
>  };
>  
>  static struct kvm_x86_init_ops svm_init_ops __initdata = {
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index ca95204f9dde..98c2890d561d 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -398,9 +398,10 @@ int nested_svm_exit_handled(struct vcpu_svm *svm);
>  int nested_svm_check_permissions(struct vcpu_svm *svm);
>  int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
>  			       bool has_error_code, u32 error_code);
> -int svm_check_nested_events(struct kvm_vcpu *vcpu);
>  int nested_svm_exit_special(struct vcpu_svm *svm);
>  
> +extern struct kvm_x86_nested_ops svm_nested_ops;
> +
>  /* avic.c */
>  
>  #define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK	(0xFF)
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index f228339cd0a0..8597141bd1c7 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -6440,12 +6440,14 @@ __init int nested_vmx_hardware_setup(struct kvm_x86_ops *ops,
>  	exit_handlers[EXIT_REASON_INVVPID]	= handle_invvpid;
>  	exit_handlers[EXIT_REASON_VMFUNC]	= handle_vmfunc;
>  
> -	ops->check_nested_events = vmx_check_nested_events;
> -	ops->get_nested_state = vmx_get_nested_state;
> -	ops->set_nested_state = vmx_set_nested_state;
> -	ops->get_vmcs12_pages = nested_get_vmcs12_pages;
> -	ops->nested_enable_evmcs = nested_enable_evmcs;
> -	ops->nested_get_evmcs_version = nested_get_evmcs_version;
> -
>  	return 0;
>  }
> +
> +struct kvm_x86_nested_ops vmx_nested_ops = {
> +	.check_nested_events = vmx_check_nested_events,
> +	.get_nested_state = vmx_get_nested_state,
> +	.set_nested_state = vmx_set_nested_state,
> +	.get_vmcs12_pages = nested_get_vmcs12_pages,
> +	.nested_enable_evmcs = nested_enable_evmcs,
> +	.nested_get_evmcs_version = nested_get_evmcs_version,
> +};
> diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
> index 1514ff4db77f..7ce9572c3d3a 100644
> --- a/arch/x86/kvm/vmx/nested.h
> +++ b/arch/x86/kvm/vmx/nested.h
> @@ -278,4 +278,6 @@ static inline bool nested_cr4_valid(struct kvm_vcpu *vcpu, unsigned long val)
>  #define nested_guest_cr4_valid	nested_cr4_valid
>  #define nested_host_cr4_valid	nested_cr4_valid
>  
> +extern struct kvm_x86_nested_ops vmx_nested_ops;
> +
>  #endif /* __KVM_X86_VMX_NESTED_H */
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 766303b31949..455cd2c8dbce 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7862,6 +7862,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
>  	.post_block = vmx_post_block,
>  
>  	.pmu_ops = &intel_pmu_ops,
> +	.nested_ops = &vmx_nested_ops,
>  
>  	.update_pi_irte = vmx_update_pi_irte,
>  
> @@ -7877,12 +7878,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
>  	.pre_leave_smm = vmx_pre_leave_smm,
>  	.enable_smi_window = enable_smi_window,
>  
> -	.check_nested_events = NULL,
> -	.get_nested_state = NULL,
> -	.set_nested_state = NULL,
> -	.get_vmcs12_pages = NULL,
> -	.nested_enable_evmcs = NULL,
> -	.nested_get_evmcs_version = NULL,
>  	.need_emulation_on_page_fault = vmx_need_emulation_on_page_fault,
>  	.apic_init_signal_blocked = vmx_apic_init_signal_blocked,
>  };
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0492baeb78ab..5bcb4569196a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3442,14 +3442,14 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  		r = KVM_X2APIC_API_VALID_FLAGS;
>  		break;
>  	case KVM_CAP_NESTED_STATE:
> -		r = kvm_x86_ops.get_nested_state ?
> -			kvm_x86_ops.get_nested_state(NULL, NULL, 0) : 0;
> +		r = kvm_x86_ops.nested_ops->get_nested_state ?
> +			kvm_x86_ops.nested_ops->get_nested_state(NULL, NULL, 0) : 0;
>  		break;
>  	case KVM_CAP_HYPERV_DIRECT_TLBFLUSH:
>  		r = kvm_x86_ops.enable_direct_tlbflush != NULL;
>  		break;
>  	case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
> -		r = kvm_x86_ops.nested_enable_evmcs != NULL;
> +		r = kvm_x86_ops.nested_ops->nested_enable_evmcs != NULL;
>  		break;
>  	default:
>  		break;
> @@ -4235,9 +4235,9 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
>  		return kvm_hv_activate_synic(vcpu, cap->cap ==
>  					     KVM_CAP_HYPERV_SYNIC2);
>  	case KVM_CAP_HYPERV_ENLIGHTENED_VMCS:
> -		if (!kvm_x86_ops.nested_enable_evmcs)
> +		if (!kvm_x86_ops.nested_ops->nested_enable_evmcs)
>  			return -ENOTTY;
> -		r = kvm_x86_ops.nested_enable_evmcs(vcpu, &vmcs_version);
> +		r = kvm_x86_ops.nested_ops->nested_enable_evmcs(vcpu, &vmcs_version);
>  		if (!r) {
>  			user_ptr = (void __user *)(uintptr_t)cap->args[0];
>  			if (copy_to_user(user_ptr, &vmcs_version,
> @@ -4552,7 +4552,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>  		u32 user_data_size;
>  
>  		r = -EINVAL;
> -		if (!kvm_x86_ops.get_nested_state)
> +		if (!kvm_x86_ops.nested_ops->get_nested_state)
>  			break;
>  
>  		BUILD_BUG_ON(sizeof(user_data_size) != sizeof(user_kvm_nested_state->size));
> @@ -4560,8 +4560,8 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>  		if (get_user(user_data_size, &user_kvm_nested_state->size))
>  			break;
>  
> -		r = kvm_x86_ops.get_nested_state(vcpu, user_kvm_nested_state,
> -						  user_data_size);
> +		r = kvm_x86_ops.nested_ops->get_nested_state(vcpu, user_kvm_nested_state,
> +							     user_data_size);
>  		if (r < 0)
>  			break;
>  
> @@ -4582,7 +4582,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>  		int idx;
>  
>  		r = -EINVAL;
> -		if (!kvm_x86_ops.set_nested_state)
> +		if (!kvm_x86_ops.nested_ops->set_nested_state)
>  			break;
>  
>  		r = -EFAULT;
> @@ -4604,7 +4604,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>  			break;
>  
>  		idx = srcu_read_lock(&vcpu->kvm->srcu);
> -		r = kvm_x86_ops.set_nested_state(vcpu, user_kvm_nested_state, &kvm_state);
> +		r = kvm_x86_ops.nested_ops->set_nested_state(vcpu, user_kvm_nested_state, &kvm_state);
>  		srcu_read_unlock(&vcpu->kvm->srcu, idx);
>  		break;
>  	}
> @@ -7700,7 +7700,7 @@ static int inject_pending_event(struct kvm_vcpu *vcpu)
>  	 * from L2 to L1.
>  	 */
>  	if (is_guest_mode(vcpu)) {
> -		r = kvm_x86_ops.check_nested_events(vcpu);
> +		r = kvm_x86_ops.nested_ops->check_nested_events(vcpu);
>  		if (r != 0)
>  			return r;
>  	}
> @@ -7762,7 +7762,7 @@ static int inject_pending_event(struct kvm_vcpu *vcpu)
>  		 * KVM_REQ_EVENT only on certain events and not unconditionally?
>  		 */
>  		if (is_guest_mode(vcpu)) {
> -			r = kvm_x86_ops.check_nested_events(vcpu);
> +			r = kvm_x86_ops.nested_ops->check_nested_events(vcpu);
>  			if (r != 0)
>  				return r;
>  		}
> @@ -8185,7 +8185,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>  
>  	if (kvm_request_pending(vcpu)) {
>  		if (kvm_check_request(KVM_REQ_GET_VMCS12_PAGES, vcpu)) {
> -			if (unlikely(!kvm_x86_ops.get_vmcs12_pages(vcpu))) {
> +			if (unlikely(!kvm_x86_ops.nested_ops->get_vmcs12_pages(vcpu))) {
>  				r = 0;
>  				goto out;
>  			}
> @@ -8528,7 +8528,7 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu)
>  static inline bool kvm_vcpu_running(struct kvm_vcpu *vcpu)
>  {
>  	if (is_guest_mode(vcpu))
> -		kvm_x86_ops.check_nested_events(vcpu);
> +		kvm_x86_ops.nested_ops->check_nested_events(vcpu);
>  
>  	return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE &&
>  		!vcpu->arch.apf.halted);

-- 
Vitaly

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