KVM: x86: Add CONFIG_KVM_IOAPIC to allow disabling in-kernel I/O APIC

Add a Kconfig to allow building KVM without support for emulating a I/O
APIC, PIC, and PIT, which is desirable for deployments that effectively
don't support a fully in-kernel IRQ chip, i.e. never expect any VMM to
create an in-kernel I/O APIC.  E.g. compiling out support eliminates a few
thousand lines of guest-facing code and gives security folks warm fuzzies.

As a bonus, wrapping relevant paths with CONFIG_KVM_IOAPIC #ifdefs makes
it much easier for readers to understand which bits and pieces exist
specifically for fully in-kernel IRQ chips.

Opportunistically convert all two in-kernel uses of __KVM_HAVE_IOAPIC to
CONFIG_KVM_IOAPIC, e.g. rather than add a second #ifdef to generate a stub
for kvm_arch_post_irq_routing_update().

Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/r/20250611213557.294358-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2025-06-11 14:35:53 -07:00
parent 2c938850d9
commit 628a27731e
12 changed files with 65 additions and 10 deletions

View File

@@ -1023,7 +1023,7 @@ void kvm_unlock_all_vcpus(struct kvm *kvm);
void vcpu_load(struct kvm_vcpu *vcpu);
void vcpu_put(struct kvm_vcpu *vcpu);
#ifdef __KVM_HAVE_IOAPIC
#ifdef CONFIG_KVM_IOAPIC
void kvm_arch_post_irq_ack_notifier_list_update(struct kvm *kvm);
#else
static inline void kvm_arch_post_irq_ack_notifier_list_update(struct kvm *kvm)