Re: [PATCH v3 12/16] KVM: Move x86's perf guest info callbacks to generic KVM

Paolo Bonzini
2021-09-22T06:41:47Z

On 22/09/21 02:05, Sean Christopherson wrote:
> Move x86's perf guest callbacks into common KVM, as they are semantically
> identical to arm64's callbacks (the only other such KVM callbacks).
> arm64 will convert to the common versions in a future patch.
>
> Implement the necessary arm64 arch hooks now to avoid having to provide
> stubs or a temporary #define (from x86) to avoid arm64 compilation errors
> when CONFIG_GUEST_PERF_EVENTS=y.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/arm64/include/asm/kvm_host.h | 8 +++++
> arch/arm64/kvm/arm.c | 5 +++
> arch/x86/include/asm/kvm_host.h | 3 ++
> arch/x86/kvm/x86.c | 53 +++++++------------------------
> include/linux/kvm_host.h | 10 ++++++
> virt/kvm/kvm_main.c | 44 +++++++++++++++++++++++++
> 6 files changed, 81 insertions(+), 42 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index ed940aec89e0..828b6eaa2c56 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -673,6 +673,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
> void kvm_perf_init(void);
> void kvm_perf_teardown(void);
>
> +#ifdef CONFIG_GUEST_PERF_EVENTS
> +static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
> +{
> + /* Any callback while a vCPU is loaded is considered to be in guest. */
> + return !!vcpu;
> +}
> +#endif
> +
> long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu);
> gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu);
> void kvm_update_stolen_time(struct kvm_vcpu *vcpu);
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index e9a2b8f27792..2b542fdc237e 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -500,6 +500,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
> return vcpu_mode_priv(vcpu);
> }
>
> +unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
> +{
> + return *vcpu_pc(vcpu);
> +}
> +
> /* Just ensure a guest exit from a particular CPU */
> static void exit_vm_noop(void *info)
> {
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 2d86a2dfc775..6efe4e03a6d2 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1543,6 +1543,9 @@ static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
> return -ENOTSUPP;
> }
>
> +#define kvm_arch_pmi_in_guest(vcpu) \
> + ((vcpu) && (vcpu)->arch.handling_intr_from_guest)
> +
> int kvm_mmu_module_init(void);
> void kvm_mmu_module_exit(void);
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 412646b973bb..1bea616402e6 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8264,43 +8264,12 @@ static void kvm_timer_init(void)
> kvmclock_cpu_online, kvmclock_cpu_down_prep);
> }
>
> -static inline bool kvm_pmi_in_guest(struct kvm_vcpu *vcpu)
> -{
> - return vcpu && vcpu->arch.handling_intr_from_guest;
> -}
> -
> -static unsigned int kvm_guest_state(void)
> -{
> - struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> - unsigned int state;
> -
> - if (!kvm_pmi_in_guest(vcpu))
> - return 0;
> -
> - state = PERF_GUEST_ACTIVE;
> - if (static_call(kvm_x86_get_cpl)(vcpu))
> - state |= PERF_GUEST_USER;
> -
> - return state;
> -}
> -
> -static unsigned long kvm_guest_get_ip(void)
> -{
> - struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> -
> - /* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
> - if (WARN_ON_ONCE(!kvm_pmi_in_guest(vcpu)))
> - return 0;
> -
> - return kvm_rip_read(vcpu);
> -}
> -
> static unsigned int kvm_handle_intel_pt_intr(void)
> {
> struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
>
> /* '0' on failure so that the !PT case can use a RET0 static call. */
> - if (!kvm_pmi_in_guest(vcpu))
> + if (!kvm_arch_pmi_in_guest(vcpu))
> return 0;
>
> kvm_make_request(KVM_REQ_PMI, vcpu);
> @@ -8309,12 +8278,6 @@ static unsigned int kvm_handle_intel_pt_intr(void)
> return 1;
> }
>
> -static struct perf_guest_info_callbacks kvm_guest_cbs = {
> - .state = kvm_guest_state,
> - .get_ip = kvm_guest_get_ip,
> - .handle_intel_pt_intr = NULL,
> -};
> -
> #ifdef CONFIG_X86_64
> static void pvclock_gtod_update_fn(struct work_struct *work)
> {
> @@ -11068,9 +11031,11 @@ int kvm_arch_hardware_setup(void *opaque)
> memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
> kvm_ops_static_call_update();
>
> + /* Temporary ugliness. */
> if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
> - kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
> - perf_register_guest_info_callbacks(&kvm_guest_cbs);
> + kvm_register_perf_callbacks(kvm_handle_intel_pt_intr);
> + else
> + kvm_register_perf_callbacks(NULL);
>
> if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
> supported_xss = 0;
> @@ -11099,8 +11064,7 @@ int kvm_arch_hardware_setup(void *opaque)
>
> void kvm_arch_hardware_unsetup(void)
> {
> - perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
> - kvm_guest_cbs.handle_intel_pt_intr = NULL;
> + kvm_unregister_perf_callbacks();
>
> static_call(kvm_x86_hardware_unsetup)();
> }
> @@ -11727,6 +11691,11 @@ bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
> return vcpu->arch.preempted_in_kernel;
> }
>
> +unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu)
> +{
> + return kvm_rip_read(vcpu);
> +}
> +
> int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
> {
> return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index e4d712e9f760..b9255a6439f2 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1163,6 +1163,16 @@ static inline bool kvm_arch_intc_initialized(struct kvm *kvm)
> }
> #endif
>
> +#ifdef CONFIG_GUEST_PERF_EVENTS
> +unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu);
> +
> +void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void));
> +void kvm_unregister_perf_callbacks(void);
> +#else
> +static inline void kvm_register_perf_callbacks(void *ign) {}
> +static inline void kvm_unregister_perf_callbacks(void) {}
> +#endif /* CONFIG_GUEST_PERF_EVENTS */
> +
> int kvm_arch_init_vm(struct kvm *kvm, unsigned long type);
> void kvm_arch_destroy_vm(struct kvm *kvm);
> void kvm_arch_sync_events(struct kvm *kvm);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 3e67c93ca403..179fb110a00f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -5460,6 +5460,50 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
> return &kvm_running_vcpu;
> }
>
> +#ifdef CONFIG_GUEST_PERF_EVENTS
> +static unsigned int kvm_guest_state(void)
> +{
> + struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> + unsigned int state;
> +
> + if (!kvm_arch_pmi_in_guest(vcpu))
> + return 0;
> +
> + state = PERF_GUEST_ACTIVE;
> + if (!kvm_arch_vcpu_in_kernel(vcpu))
> + state |= PERF_GUEST_USER;
> +
> + return state;
> +}
> +
> +static unsigned long kvm_guest_get_ip(void)
> +{
> + struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
> +
> + /* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
> + if (WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)))
> + return 0;
> +
> + return kvm_arch_vcpu_get_ip(vcpu);
> +}
> +
> +static struct perf_guest_info_callbacks kvm_guest_cbs = {
> + .state = kvm_guest_state,
> + .get_ip = kvm_guest_get_ip,
> + .handle_intel_pt_intr = NULL,
> +};
> +
> +void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
> +{
> + kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
> + perf_register_guest_info_callbacks(&kvm_guest_cbs);
> +}
> +void kvm_unregister_perf_callbacks(void)
> +{
> + perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
> +}
> +#endif
> +
> struct kvm_cpu_compat_check {
> void *opaque;
> int *ret;
>

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