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KVM: x86: Open code setting/clearing of bits in the ISR

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Remove __apic_test_and_set_vector() and __apic_test_and_clear_vector(),
because the _only_ register that's safe to modify with a non-atomic
operation is ISR, because KVM isn't running the vCPU, i.e. hardware can't
service an IRQ or process an EOI for the relevant (virtual) APIC.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20250709033242.267892-2-Neeraj.Upadhyay@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Neeraj Upadhyay 2025-07-09 09:02:08 +05:30 committed by Sean Christopherson
parent d7b8f8e208
commit ac48017020
1 changed files with 7 additions and 12 deletions
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19
arch/x86/kvm/lapic.c
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@ -125,16 +125,6 @@ bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector)
apic_test_vector(vector, apic->regs + APIC_IRR);
}
static inline int __apic_test_and_set_vector(int vec, void *bitmap)
{
return __test_and_set_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
}
static inline int __apic_test_and_clear_vector(int vec, void *bitmap)
{
return __test_and_clear_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
}
__read_mostly DEFINE_STATIC_KEY_FALSE(kvm_has_noapic_vcpu);
EXPORT_SYMBOL_GPL(kvm_has_noapic_vcpu);
@ -744,9 +734,14 @@ void kvm_apic_clear_irr(struct kvm_vcpu *vcpu, int vec)
}
EXPORT_SYMBOL_GPL(kvm_apic_clear_irr);
static void *apic_vector_to_isr(int vec, struct kvm_lapic *apic)
{
return apic->regs + APIC_ISR + REG_POS(vec);
}
static inline void apic_set_isr(int vec, struct kvm_lapic *apic)
{
if (__apic_test_and_set_vector(vec, apic->regs + APIC_ISR))
if (__test_and_set_bit(VEC_POS(vec), apic_vector_to_isr(vec, apic)))
return;
/*
@ -789,7 +784,7 @@ static inline int apic_find_highest_isr(struct kvm_lapic *apic)
static inline void apic_clear_isr(int vec, struct kvm_lapic *apic)
{
if (!__apic_test_and_clear_vector(vec, apic->regs + APIC_ISR))
if (!__test_and_clear_bit(VEC_POS(vec), apic_vector_to_isr(vec, apic)))
return;
/*