[PATCH v9 1/2] kvm: Use a reserved IRQ source ID for irqfd

Alex Williamson
2012-08-21T19:29:15Z

KVM_IRQFD currently uses the reserved KVM_USERSPACE_IRQ_SOURCE_ID
which is also shared with userspace injection methods like
KVM_IRQ_LINE. This can cause a conflict if an irqfd triggers on
a GSI asserted through KVM_IRQ_LINE. Move irqfd to it's own
reserved IRQ source ID. Add a capability for userspace to test
for this fix.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

arch/x86/kvm/x86.c | 3 +++
include/linux/kvm.h | 1 +
include/linux/kvm_host.h | 1 +
virt/kvm/eventfd.c | 6 +++---
4 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 42bce48..cd98673 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2174,6 +2174,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_GET_TSC_KHZ:
case KVM_CAP_PCI_2_3:
case KVM_CAP_KVMCLOCK_CTRL:
+ case KVM_CAP_IRQFD_IRQ_SOURCE_ID:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -6258,6 +6259,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)

/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap);
+ /* Reserve bit 1 of irq_sources_bitmap for irqfd irq source */
+ set_bit(KVM_IRQFD_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap);

raw_spin_lock_init(&kvm->arch.tsc_write_lock);

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 2ce09aa..ae66b9c 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -618,6 +618,7 @@ struct kvm_ppc_smmu_info {
#define KVM_CAP_PPC_GET_SMMU_INFO 78
#define KVM_CAP_S390_COW 79
#define KVM_CAP_PPC_ALLOC_HTAB 80
+#define KVM_CAP_IRQFD_IRQ_SOURCE_ID 81

#ifdef KVM_CAP_IRQ_ROUTING

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b70b48b..b763230 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -71,6 +71,7 @@
#define KVM_REQ_PMI 17

#define KVM_USERSPACE_IRQ_SOURCE_ID 0
+#define KVM_IRQFD_IRQ_SOURCE_ID 1

struct kvm;
struct kvm_vcpu;
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 7d7e2aa..2245cfa 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -67,8 +67,8 @@ irqfd_inject(struct work_struct *work)
struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
struct kvm *kvm = irqfd->kvm;

- kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
- kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
+ kvm_set_irq(kvm, KVM_IRQFD_IRQ_SOURCE_ID, irqfd->gsi, 1);
+ kvm_set_irq(kvm, KVM_IRQFD_IRQ_SOURCE_ID, irqfd->gsi, 0);
}

/*
@@ -138,7 +138,7 @@ irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
irq = rcu_dereference(irqfd->irq_entry);
/* An event has been signaled, inject an interrupt */
if (irq)
- kvm_set_msi(irq, kvm, KVM_USERSPACE_IRQ_SOURCE_ID, 1);
+ kvm_set_msi(irq, kvm, KVM_IRQFD_IRQ_SOURCE_ID, 1);
else
schedule_work(&irqfd->inject);
rcu_read_unlock();