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Date: Fri, 09 Dec 2022 00:03:35 +0200
From: Maxim Levitsky <mlevitsk@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>,
Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
Alejandro Jimenez <alejandro.j.jimenez@...cle.com>,
Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
Li RongQing <lirongqing@...du.com>
Subject: Re: [PATCH v4 32/32] KVM: x86: Track required APICv inhibits with
variable, not callback
On Sat, 2022-10-01 at 00:59 +0000, Sean Christopherson wrote:
> Track the per-vendor required APICv inhibits with a variable instead of
> calling into vendor code every time KVM wants to query the set of
> required inhibits. The required inhibits are a property of the vendor's
> virtualization architecture, i.e. are 100% static.
>
> Using a variable allows the compiler to inline the check, e.g. generate
> a single-uop TEST+Jcc, and thus eliminates any desire to avoid checking
> inhibits for performance reasons.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
> arch/x86/include/asm/kvm-x86-ops.h | 1 -
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/svm/avic.c | 20 --------------------
> arch/x86/kvm/svm/svm.c | 2 +-
> arch/x86/kvm/svm/svm.h | 17 ++++++++++++++++-
> arch/x86/kvm/vmx/vmx.c | 24 +++++++++++-------------
> arch/x86/kvm/x86.c | 9 +++++++--
> 7 files changed, 36 insertions(+), 39 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> index 82ba4a564e58..533d0e804e5a 100644
> --- a/arch/x86/include/asm/kvm-x86-ops.h
> +++ b/arch/x86/include/asm/kvm-x86-ops.h
> @@ -76,7 +76,6 @@ KVM_X86_OP(set_nmi_mask)
> KVM_X86_OP(enable_nmi_window)
> KVM_X86_OP(enable_irq_window)
> KVM_X86_OP_OPTIONAL(update_cr8_intercept)
> -KVM_X86_OP(check_apicv_inhibit_reasons)
> KVM_X86_OP(refresh_apicv_exec_ctrl)
> KVM_X86_OP_OPTIONAL(hwapic_irr_update)
> KVM_X86_OP_OPTIONAL(hwapic_isr_update)
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 4fd06965c773..41d1c684a1e1 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1566,7 +1566,7 @@ struct kvm_x86_ops {
> void (*enable_nmi_window)(struct kvm_vcpu *vcpu);
> void (*enable_irq_window)(struct kvm_vcpu *vcpu);
> void (*update_cr8_intercept)(struct kvm_vcpu *vcpu, int tpr, int irr);
> - bool (*check_apicv_inhibit_reasons)(enum kvm_apicv_inhibit reason);
> + const unsigned long required_apicv_inhibits;
> void (*refresh_apicv_exec_ctrl)(struct kvm_vcpu *vcpu);
> void (*hwapic_irr_update)(struct kvm_vcpu *vcpu, int max_irr);
> void (*hwapic_isr_update)(int isr);
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 35b0ef877e53..5b25944274b5 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -966,26 +966,6 @@ int avic_pi_update_irte(struct kvm *kvm, unsigned int host_irq,
> return ret;
> }
>
> -bool avic_check_apicv_inhibit_reasons(enum kvm_apicv_inhibit reason)
> -{
> - ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
> - BIT(APICV_INHIBIT_REASON_ABSENT) |
> - BIT(APICV_INHIBIT_REASON_HYPERV) |
> - BIT(APICV_INHIBIT_REASON_NESTED) |
> - BIT(APICV_INHIBIT_REASON_IRQWIN) |
> - BIT(APICV_INHIBIT_REASON_PIT_REINJ) |
> - BIT(APICV_INHIBIT_REASON_BLOCKIRQ) |
> - BIT(APICV_INHIBIT_REASON_SEV) |
> - BIT(APICV_INHIBIT_REASON_PHYSICAL_ID_ALIASED) |
> - BIT(APICV_INHIBIT_REASON_APIC_ID_MODIFIED) |
> - BIT(APICV_INHIBIT_REASON_APIC_BASE_MODIFIED) |
> - BIT(APICV_INHIBIT_REASON_X2APIC) |
> - BIT(APICV_INHIBIT_REASON_LOGICAL_ID_ALIASED);
> -
> - return supported & BIT(reason);
> -}
> -
> -
> static inline int
> avic_update_iommu_vcpu_affinity(struct kvm_vcpu *vcpu, int cpu, bool r)
> {
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 37fe7bcf8496..6bca3f9f39e6 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4800,8 +4800,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
> .update_cr8_intercept = svm_update_cr8_intercept,
> .set_virtual_apic_mode = avic_refresh_virtual_apic_mode,
> .refresh_apicv_exec_ctrl = avic_refresh_apicv_exec_ctrl,
> - .check_apicv_inhibit_reasons = avic_check_apicv_inhibit_reasons,
> .apicv_post_state_restore = avic_apicv_post_state_restore,
> + .required_apicv_inhibits = AVIC_REQUIRED_APICV_INHIBITS,
>
> .get_exit_info = svm_get_exit_info,
>
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 29c334a932c3..dfde85782da5 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -619,6 +619,22 @@ void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb);
> extern struct kvm_x86_nested_ops svm_nested_ops;
>
> /* avic.c */
> +#define AVIC_REQUIRED_APICV_INHIBITS \
> +( \
> + BIT(APICV_INHIBIT_REASON_DISABLE) | \
> + BIT(APICV_INHIBIT_REASON_ABSENT) | \
> + BIT(APICV_INHIBIT_REASON_HYPERV) | \
> + BIT(APICV_INHIBIT_REASON_NESTED) | \
> + BIT(APICV_INHIBIT_REASON_IRQWIN) | \
> + BIT(APICV_INHIBIT_REASON_PIT_REINJ) | \
> + BIT(APICV_INHIBIT_REASON_BLOCKIRQ) | \
> + BIT(APICV_INHIBIT_REASON_SEV) | \
> + BIT(APICV_INHIBIT_REASON_PHYSICAL_ID_ALIASED) | \
> + BIT(APICV_INHIBIT_REASON_APIC_ID_MODIFIED) | \
> + BIT(APICV_INHIBIT_REASON_APIC_BASE_MODIFIED) | \
> + BIT(APICV_INHIBIT_REASON_X2APIC) | \
> + BIT(APICV_INHIBIT_REASON_LOGICAL_ID_ALIASED) \
> +)
>
> bool avic_hardware_setup(struct kvm_x86_ops *ops);
> int avic_ga_log_notifier(u32 ga_tag);
> @@ -632,7 +648,6 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
> void avic_vcpu_put(struct kvm_vcpu *vcpu);
> void avic_apicv_post_state_restore(struct kvm_vcpu *vcpu);
> void avic_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu);
> -bool avic_check_apicv_inhibit_reasons(enum kvm_apicv_inhibit reason);
> int avic_pi_update_irte(struct kvm *kvm, unsigned int host_irq,
> uint32_t guest_irq, bool set);
> void avic_vcpu_blocking(struct kvm_vcpu *vcpu);
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 5920166d7260..54bc447ba87e 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7949,18 +7949,16 @@ static void vmx_hardware_unsetup(void)
> free_kvm_area();
> }
>
> -static bool vmx_check_apicv_inhibit_reasons(enum kvm_apicv_inhibit reason)
> -{
> - ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
> - BIT(APICV_INHIBIT_REASON_ABSENT) |
> - BIT(APICV_INHIBIT_REASON_HYPERV) |
> - BIT(APICV_INHIBIT_REASON_BLOCKIRQ) |
> - BIT(APICV_INHIBIT_REASON_PHYSICAL_ID_ALIASED) |
> - BIT(APICV_INHIBIT_REASON_APIC_ID_MODIFIED) |
> - BIT(APICV_INHIBIT_REASON_APIC_BASE_MODIFIED);
> -
> - return supported & BIT(reason);
> -}
> +#define VMX_REQUIRED_APICV_INHIBITS \
> +( \
> + BIT(APICV_INHIBIT_REASON_DISABLE)| \
> + BIT(APICV_INHIBIT_REASON_ABSENT) | \
> + BIT(APICV_INHIBIT_REASON_HYPERV) | \
> + BIT(APICV_INHIBIT_REASON_BLOCKIRQ) | \
> + BIT(APICV_INHIBIT_REASON_PHYSICAL_ID_ALIASED) | \
> + BIT(APICV_INHIBIT_REASON_APIC_ID_MODIFIED) | \
> + BIT(APICV_INHIBIT_REASON_APIC_BASE_MODIFIED) \
> +)
>
> static void vmx_vm_destroy(struct kvm *kvm)
> {
> @@ -8044,7 +8042,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
> .refresh_apicv_exec_ctrl = vmx_refresh_apicv_exec_ctrl,
> .load_eoi_exitmap = vmx_load_eoi_exitmap,
> .apicv_post_state_restore = vmx_apicv_post_state_restore,
> - .check_apicv_inhibit_reasons = vmx_check_apicv_inhibit_reasons,
> + .required_apicv_inhibits = VMX_REQUIRED_APICV_INHIBITS,
> .hwapic_irr_update = vmx_hwapic_irr_update,
> .hwapic_isr_update = vmx_hwapic_isr_update,
> .guest_apic_has_interrupt = vmx_guest_apic_has_interrupt,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a20002924eb4..b307637d9200 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10251,6 +10251,11 @@ void kvm_make_scan_ioapic_request(struct kvm *kvm)
> kvm_make_all_cpus_request(kvm, KVM_REQ_SCAN_IOAPIC);
> }
>
> +static bool kvm_is_required_apicv_inhibit(enum kvm_apicv_inhibit reason)
> +{
> + return kvm_x86_ops.required_apicv_inhibits & BIT(reason);
> +}
> +
> void __kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu)
> {
> struct kvm_lapic *apic = vcpu->arch.apic;
> @@ -10294,7 +10299,7 @@ static void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu)
> return;
>
> if (apic_x2apic_mode(vcpu->arch.apic) &&
> - static_call(kvm_x86_check_apicv_inhibit_reasons)(APICV_INHIBIT_REASON_X2APIC))
> + kvm_is_required_apicv_inhibit(APICV_INHIBIT_REASON_X2APIC))
> kvm_inhibit_apic_access_page(vcpu);
>
> __kvm_vcpu_update_apicv(vcpu);
> @@ -10307,7 +10312,7 @@ void __kvm_set_or_clear_apicv_inhibit(struct kvm *kvm,
>
> lockdep_assert_held_write(&kvm->arch.apicv_update_lock);
>
> - if (!static_call(kvm_x86_check_apicv_inhibit_reasons)(reason))
> + if (!kvm_is_required_apicv_inhibit(reason))
> return;
>
> old = new = kvm->arch.apicv_inhibit_reasons;
Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
Best regards,
Maxim Levitsky
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