From 529df65e394e30a78f2633b575fd81fa5b973e30 Mon Sep 17 00:00:00 2001 From: Chris Lalancette Date: Mon, 21 Jun 2010 11:29:40 -0400 Subject: [PATCH] KVM: Search the LAPIC's for one that will accept a PIC interrupt Older versions of 32-bit linux have a "Checking 'hlt' instruction" test where they repeatedly call the 'hlt' instruction, and then expect a timer interrupt to kick the CPU out of halt. This happens before any LAPIC or IOAPIC setup happens, which means that all of the APIC's are in virtual wire mode at this point. Unfortunately, the current implementation of virtual wire mode is hardcoded to only kick the BSP, so if a crash+kexec occurs on a different vcpu, it will never get kicked. This patch makes pic_unlock() do the equivalent of kvm_irq_delivery_to_apic() for the IOAPIC code. That is, it runs through all of the vcpus looking for one that is in virtual wire mode. In the normal case where LAPICs and IOAPICs are configured, this won't be used at all. In the bootstrap phase of a modern OS, before the LAPICs and IOAPICs are configured, this will have exactly the same behavior as today; VCPU0 is always looked at first, so it will always get out of the loop after the first iteration. This will only go through the loop more than once during a kexec/kdump, in which case it will only do it a few times until the kexec'ed kernel programs the LAPIC and IOAPIC. Signed-off-by: Chris Lalancette Signed-off-by: Avi Kivity --- arch/x86/kvm/i8259.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c index bc10f0bd3819..819b748a33f9 100644 --- a/arch/x86/kvm/i8259.c +++ b/arch/x86/kvm/i8259.c @@ -46,16 +46,25 @@ static void pic_unlock(struct kvm_pic *s) __releases(&s->lock) { bool wakeup = s->wakeup_needed; - struct kvm_vcpu *vcpu; + struct kvm_vcpu *vcpu, *found = NULL; + int i; s->wakeup_needed = false; raw_spin_unlock(&s->lock); if (wakeup) { - vcpu = s->kvm->bsp_vcpu; - if (vcpu) - kvm_vcpu_kick(vcpu); + kvm_for_each_vcpu(i, vcpu, s->kvm) { + if (kvm_apic_accept_pic_intr(vcpu)) { + found = vcpu; + break; + } + } + + if (!found) + found = s->kvm->bsp_vcpu; + + kvm_vcpu_kick(found); } } -- 2.39.5