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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jason Wang <jasowang@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>
Subject: [PATCH 5.16 0950/1017] Revert "virtio-pci: harden INTX interrupts"
Date:   Tue,  5 Apr 2022 09:31:03 +0200
Message-Id: <20220405070422.411415860@linuxfoundation.org>
In-Reply-To: <20220405070354.155796697@linuxfoundation.org>
References: <20220405070354.155796697@linuxfoundation.org>
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From: Jason Wang <jasowang@redhat.com>

commit 7b79edfb862d6b1ecc66479419ae67a7db2d02e3 upstream.

This reverts commit 080cd7c3ac8701081d143a15ba17dd9475313188. Since
the MSI-X interrupts hardening will be reverted in the next patch. We
will rework the interrupt hardening in the future.

Fixes: 080cd7c3ac87 ("virtio-pci: harden INTX interrupts")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220323031524.6555-1-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/virtio/virtio_pci_common.c |   23 ++---------------------
 drivers/virtio/virtio_pci_common.h |    1 -
 2 files changed, 2 insertions(+), 22 deletions(-)

--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -30,16 +30,8 @@ void vp_disable_cbs(struct virtio_device
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	int i;
 
-	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);
+	if (vp_dev->intx_enabled)
 		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));
@@ -51,16 +43,8 @@ void vp_enable_cbs(struct virtio_device
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	int i;
 
-	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);
+	if (vp_dev->intx_enabled)
 		return;
-	}
 
 	for (i = 0; i < vp_dev->msix_vectors; ++i)
 		enable_irq(pci_irq_vector(vp_dev->pci_dev, i));
@@ -113,9 +97,6 @@ static irqreturn_t vp_interrupt(int irq,
 	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);
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -63,7 +63,6 @@ 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. */