Commit 3d30bfcb authored by David Matlack's avatar David Matlack Committed by Sean Christopherson
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KVM: x86/mmu: Stop kicking vCPUs to sync the dirty log when PML is disabled 



Stop kicking vCPUs in kvm_arch_sync_dirty_log() when PML is disabled.
Kicking vCPUs when PML is disabled serves no purpose and could
negatively impact guest performance.

This restores KVM's behavior to prior to 5.12 commit a018eba5 ("KVM:
x86: Move MMU's PML logic to common code"), which replaced a
static_call_cond(kvm_x86_flush_log_dirty) with unconditional calls to
kvm_vcpu_kick().

Fixes: a018eba5 ("KVM: x86: Move MMU's PML logic to common code")
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20231016221228.1348318-1-dmatlack@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 26951ec8

arch/x86/kvm/x86.c

+3 −0
Original line number Diff line number Diff line
@@ -6355,6 +6355,9 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) 
	struct kvm_vcpu *vcpu;

	unsigned long i;



	if (!kvm_x86_ops.cpu_dirty_log_size)

		return;



	kvm_for_each_vcpu(i, vcpu, kvm)

		kvm_vcpu_kick(vcpu);

}