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authorJason Wang <jasowang@redhat.com>2021-10-19 09:01:47 +0200
committerMichael S. Tsirkin <mst@redhat.com>2021-11-01 10:26:48 +0100
commit080cd7c3ac8701081d143a15ba17dd9475313188 (patch)
tree4f05ff73855daeacdd2bad9098b1c9ee4a22e9b2 /drivers/virtio
parentvirtio_pci: harden MSI-X interrupts (diff)
downloadlinux-080cd7c3ac8701081d143a15ba17dd9475313188.tar.xz
linux-080cd7c3ac8701081d143a15ba17dd9475313188.zip
virtio-pci: harden INTX interrupts
This patch tries to make sure the virtio interrupt handler for INTX won't be called after a reset and before virtio_device_ready(). We can't use IRQF_NO_AUTOEN since we're using shared interrupt (IRQF_SHARED). So this patch tracks the INTX enabling status in a new intx_soft_enabled variable and toggle it during in vp_disable/enable_vectors(). The INTX interrupt handler will check intx_soft_enabled before processing the actual interrupt. Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Jason Wang <jasowang@redhat.com> Link: https://lore.kernel.org/r/20211019070152.8236-6-jasowang@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio_pci_common.c23
-rw-r--r--drivers/virtio/virtio_pci_common.h1
2 files changed, 22 insertions, 2 deletions
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 3f51fdb7be45..fdbde1db5ec5 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -30,8 +30,16 @@ void vp_disable_cbs(struct virtio_device *vdev)
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
int i;
- if (vp_dev->intx_enabled)
+ if (vp_dev->intx_enabled) {
+ /*
+ * The below synchronize() guarantees that any
+ * interrupt for this line arriving after
+ * synchronize_irq() has completed is guaranteed to see
+ * intx_soft_enabled == false.
+ */
+ WRITE_ONCE(vp_dev->intx_soft_enabled, false);
synchronize_irq(vp_dev->pci_dev->irq);
+ }
for (i = 0; i < vp_dev->msix_vectors; ++i)
disable_irq(pci_irq_vector(vp_dev->pci_dev, i));
@@ -43,8 +51,16 @@ void vp_enable_cbs(struct virtio_device *vdev)
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
int i;
- if (vp_dev->intx_enabled)
+ if (vp_dev->intx_enabled) {
+ disable_irq(vp_dev->pci_dev->irq);
+ /*
+ * The above disable_irq() provides TSO ordering and
+ * as such promotes the below store to store-release.
+ */
+ WRITE_ONCE(vp_dev->intx_soft_enabled, true);
+ enable_irq(vp_dev->pci_dev->irq);
return;
+ }
for (i = 0; i < vp_dev->msix_vectors; ++i)
enable_irq(pci_irq_vector(vp_dev->pci_dev, i));
@@ -97,6 +113,9 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
struct virtio_pci_device *vp_dev = opaque;
u8 isr;
+ if (!READ_ONCE(vp_dev->intx_soft_enabled))
+ return IRQ_NONE;
+
/* reading the ISR has the effect of also clearing it so it's very
* important to save off the value. */
isr = ioread8(vp_dev->isr);
diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
index d3c6f72c7390..23f6c5c678d5 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -63,6 +63,7 @@ struct virtio_pci_device {
/* MSI-X support */
int msix_enabled;
int intx_enabled;
+ bool intx_soft_enabled;
cpumask_var_t *msix_affinity_masks;
/* Name strings for interrupts. This size should be enough,
* and I'm too lazy to allocate each name separately. */