Commit 080cd7c3 authored by Jason Wang's avatar Jason Wang Committed by Michael S. Tsirkin
Browse files

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: default avatarJason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20211019070152.8236-6-jasowang@redhat.com


Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 9e35276a

drivers/virtio/virtio_pci_common.c

+21 −2
Original line number Diff line number Diff line
@@ -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);

drivers/virtio/virtio_pci_common.h

+1 −0
Original line number Diff line number Diff line
@@ -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. */