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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>
This commit is contained in:
Jason Wang 2021-10-19 15:01:47 +08:00 committed by Michael S. Tsirkin
parent 9e35276a53
commit 080cd7c3ac
2 changed files with 22 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/virtio/virtio_pci_common.c
View File

@ -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);

1
drivers/virtio/virtio_pci_common.h
View File

@ -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. */