Add an API to inject IRQ from atomic context.
Return EWOULDBLOCK if impossible (e.g. for multicast).
Only MSI is supported ATM.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
include/linux/kvm_host.h | 1 +
virt/kvm/irq_comm.c | 83 +++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 72 insertions(+), 12 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 93bfc9f..e165c09 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -677,6 +677,7 @@ void kvm_get_intr_delivery_bitmask(struct kvm_ioapic *ioapic,
unsigned long *deliver_bitmask);
#endif
int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level);
+int kvm_set_irq_inatomic(struct kvm *kvm, int irq_source_id, u32 irq, int level);
int kvm_set_msi(struct kvm_kernel_irq_routing_entry *irq_entry, struct kvm *kvm,
int irq_source_id, int level);
void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin);
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 2eb58af..656fa45 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -102,6 +102,23 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
return r;
}
+static inline void kvm_set_msi_irq(struct kvm_kernel_irq_routing_entry *e,
+ struct kvm_lapic_irq *irq)
+{
+ trace_kvm_msi_set_irq(e->msi.address_lo, e->msi.data);
+
+ irq->dest_id = (e->msi.address_lo &
+ MSI_ADDR_DEST_ID_MASK) >> MSI_ADDR_DEST_ID_SHIFT;
+ irq->vector = (e->msi.data &
+ MSI_DATA_VECTOR_MASK) >> MSI_DATA_VECTOR_SHIFT;
+ irq->dest_mode = (1 << MSI_ADDR_DEST_MODE_SHIFT) & e->msi.address_lo;
+ irq->trig_mode = (1 << MSI_DATA_TRIGGER_SHIFT) & e->msi.data;
+ irq->delivery_mode = e->msi.data & 0x700;
+ irq->level = 1;
+ irq->shorthand = 0;
+ /* TODO Deal with RH bit of MSI message address */
+}
+
int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
struct kvm *kvm, int irq_source_id, int level)
{
@@ -110,22 +127,26 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
if (!level)
return -1;
- trace_kvm_msi_set_irq(e->msi.address_lo, e->msi.data);
+ kvm_set_msi_irq(e, &irq);
- irq.dest_id = (e->msi.address_lo &
- MSI_ADDR_DEST_ID_MASK) >> MSI_ADDR_DEST_ID_SHIFT;
- irq.vector = (e->msi.data &
- MSI_DATA_VECTOR_MASK) >> MSI_DATA_VECTOR_SHIFT;
- irq.dest_mode = (1 << MSI_ADDR_DEST_MODE_SHIFT) & e->msi.address_lo;
- irq.trig_mode = (1 << MSI_DATA_TRIGGER_SHIFT) & e->msi.data;
- irq.delivery_mode = e->msi.data & 0x700;
- irq.level = 1;
- irq.shorthand = 0;
-
- /* TODO Deal with RH bit of MSI message address */
return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
}
+
+static int kvm_set_msi_inatomic(struct kvm_kernel_irq_routing_entry *e,
+ struct kvm *kvm)
+{
+ struct kvm_lapic_irq irq;
+ int r;
+
+ kvm_set_msi_irq(e, &irq);
+
+ if (kvm_irq_delivery_to_apic_fast(kvm, NULL, &irq, &r))
+ return r;
+ else
+ return -EWOULDBLOCK;
+}
+
int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi)
{
struct kvm_kernel_irq_routing_entry route;
@@ -178,6 +199,44 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level)
return ret;
}
+/*
+ * Deliver an IRQ in an atomic context if we can, or return a failure,
+ * user can retry in a process context.
+ * Return value:
+ * -EWOULDBLOCK - Can't deliver in atomic context: retry in a process context.
+ * Other values - No need to retry.
+ */
+int kvm_set_irq_inatomic(struct kvm *kvm, int irq_source_id, u32 irq, int level)
+{
+ struct kvm_kernel_irq_routing_entry *e;
+ int ret = -EINVAL;
+ struct kvm_irq_routing_table *irq_rt;
+ struct hlist_node *n;
+
+ trace_kvm_set_irq(irq, level, irq_source_id);
+
+ /*
+ * Injection into either PIC or IOAPIC might need to scan all CPUs,
+ * which would need to be retried from thread context; when same GSI
+ * is connected to both PIC and IOAPIC, we'd have to report a
+ * partial failure here.
+ * Since there's no easy way to do this, we only support injecting MSI
+ * which is limited to 1:1 GSI mapping.
+ */
+ rcu_read_lock();
+ irq_rt = rcu_dereference(kvm->irq_routing);
+ if (irq < irq_rt->nr_rt_entries)
+ hlist_for_each_entry(e, n, &irq_rt->map[irq], link) {
+ if (likely(e->type == KVM_IRQ_ROUTING_MSI))
+ ret = kvm_set_msi_inatomic(e, kvm);
+ else
+ ret = -EWOULDBLOCK;
+ break;
+ }
+ rcu_read_unlock();
+ return ret;
+}
+
void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
{
struct kvm_irq_ack_notifier *kian;
--
MST
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