[PATCH v5 31/33] KVM: x86: Track required APICv inhibits with variable, not callback

Sean Christopherson
2023-01-06T01:16:34Z

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.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/kvm-x86-ops.h | 1 -
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm/avic.c | 19 -------------------
arch/x86/kvm/svm/svm.c | 2 +-
arch/x86/kvm/svm/svm.h | 16 +++++++++++++++-
arch/x86/kvm/vmx/vmx.c | 24 +++++++++++-------------
arch/x86/kvm/x86.c | 2 +-
7 files changed, 29 insertions(+), 36 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index abccd51dcfca..84f43caef9b7 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 b41a01b3a4af..7ca854714ccd 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1623,6 +1623,7 @@ struct kvm_x86_ops {
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;
bool allow_apicv_in_x2apic_without_x2apic_virtualization;
void (*refresh_apicv_exec_ctrl)(struct kvm_vcpu *vcpu);
void (*hwapic_irr_update)(struct kvm_vcpu *vcpu, int max_irr);
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 80f346b79c62..14677bc31b83 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -963,25 +963,6 @@ 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_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 9f172f2de195..f2453df77727 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4773,8 +4773,8 @@ 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 546825c82490..41eabb098b13 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -621,6 +621,21 @@ 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_LOGICAL_ID_ALIASED) \
+)

bool avic_hardware_setup(struct kvm_x86_ops *ops);
int avic_ga_log_notifier(u32 ga_tag);
@@ -634,7 +649,6 @@ 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 ef84d11a0fe4..ad2ac66ef32e 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8023,18 +8023,16 @@ 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)
{
@@ -8118,7 +8116,7 @@ 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 1abe3f1e821c..5becce5bd45a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10112,7 +10112,7 @@ 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_x86_ops.required_apicv_inhibits & BIT(reason)))
return;

old = new = kvm->arch.apicv_inhibit_reasons;
--
2.39.0.314.g84b9a713c41-goog