[PATCH 7/9] virtio-pci: harden INTX interrupts
From: Jason Wang <jasowang@redhat.com>
Date: 2021-09-13 05:55:04
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lkml
Subsystem:
the rest, virtio core · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang
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. Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/virtio/virtio_pci_common.c | 18 ++++++++++++++++-- drivers/virtio/virtio_pci_common.h | 1 + 2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 0b9523e6dd39..835197151dc1 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c@@ -30,8 +30,12 @@ void vp_disable_vectors(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) { + vp_dev->intx_soft_enabled = false; + /* ensure the vp_interrupt see this intx_soft_enabled value */ + smp_wmb(); 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 +47,12 @@ void vp_enable_vectors(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) { + vp_dev->intx_soft_enabled = true; + /* ensure the vp_interrupt see this intx_soft_enabled value */ + smp_wmb(); return; + } for (i = 0; i < vp_dev->msix_vectors; ++i) enable_irq(pci_irq_vector(vp_dev->pci_dev, i));
@@ -97,6 +105,12 @@ static irqreturn_t vp_interrupt(int irq, void *opaque) struct virtio_pci_device *vp_dev = opaque; u8 isr; + if (!vp_dev->intx_soft_enabled) + return IRQ_NONE; + + /* read intx_soft_enabled before read others */ + smp_rmb(); + /* 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 a235ce9ff6a5..3c06e0f92ee4 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h@@ -64,6 +64,7 @@ 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. */
--
2.25.1
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