[RFC PATCH] virtio: avoid hanging forever in reset
From: Radu Rendec
Date: Tue Sep 01 2026 - 22:08:29 EST
Under certain conditions(*) vp_modern_get_status() can always return
0xff. This has a ripple effect that ultimately makes the system fail to
boot if the drivers are built-in and the virtio devices are probed
during boot:
* vp_reset() for the virtio-net-pci device spins forever in the loop
around vp_modern_get_status(mdev), which always returns 0xff.
* vp_reset() is called in the context of the probe() function for the
virtio-net-pci device, so probe() never returns.
* the init task gets stuck in wait_for_device_probe() before it
executes the real init binary.
Add a timeout to the reset function and make the device probing fail if
the reset function times out.
(*) This is not a theoretical problem. It happens on imx8mp-evk under
Qemu due to a relatively recent change to the dw_pcie driver that's
incompatible with the dw_pcie emulation in Qemu. I reported that bug
separately as a follow up to the patch that introduced it:
https://lore.kernel.org/all/ed86629d74368c6811e9f3b8f169584c0faf71ce.camel@xxxxxxxxxx/
Signed-off-by: Radu Rendec <radu@xxxxxxxxxx>
---
drivers/remoteproc/remoteproc_virtio.c | 4 +++-
drivers/virtio/virtio.c | 8 +++++---
drivers/virtio/virtio_mmio.c | 5 ++++-
drivers/virtio/virtio_pci_legacy.c | 4 +++-
drivers/virtio/virtio_pci_modern.c | 15 ++++++++++++---
include/linux/virtio.h | 2 +-
include/linux/virtio_config.h | 2 +-
7 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
index d5e9ff045a28..d103b80b1faf 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -231,7 +231,7 @@ static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
dev_dbg(&vdev->dev, "status: %d\n", status);
}
-static void rproc_virtio_reset(struct virtio_device *vdev)
+static int rproc_virtio_reset(struct virtio_device *vdev)
{
struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
struct fw_rsc_vdev *rsc;
@@ -240,6 +240,8 @@ static void rproc_virtio_reset(struct virtio_device *vdev)
rsc->status = 0;
dev_dbg(&vdev->dev, "reset !\n");
+
+ return 0;
}
/* provide the vdev features as retrieved from the firmware */
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 75bb4ffe3b87..9542e4f7cb31 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -250,7 +250,7 @@ static int virtio_features_ok(struct virtio_device *dev)
* call/workqueue/bh. Invoking virtio_break_device then flushing any such
* contexts is one way to handle that.
* */
-void virtio_reset_device(struct virtio_device *dev)
+int virtio_reset_device(struct virtio_device *dev)
{
#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
/*
@@ -263,7 +263,7 @@ void virtio_reset_device(struct virtio_device *dev)
virtio_synchronize_cbs(dev);
#endif
- dev->config->reset(dev);
+ return dev->config->reset(dev);
}
EXPORT_SYMBOL_GPL(virtio_reset_device);
@@ -567,7 +567,9 @@ int register_virtio_device(struct virtio_device *dev)
/* We always start by resetting the device, in case a previous
* driver messed it up. This also tests that code path a little. */
- virtio_reset_device(dev);
+ err = virtio_reset_device(dev);
+ if (err)
+ goto out_of_node_put;
/* Acknowledge that we've seen the device. */
virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 316f03b97356..537d38841331 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -249,7 +249,7 @@ static void vm_set_status(struct virtio_device *vdev, u8 status)
writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
}
-static void vm_reset(struct virtio_device *vdev)
+static int vm_reset(struct virtio_device *vdev)
{
struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
@@ -260,7 +260,10 @@ static void vm_reset(struct virtio_device *vdev)
/* Wait for reset to complete. */
while (vm_get_status(vdev))
fsleep(1000);
+ /* TODO: add timeout */
}
+
+ return 0;
}
diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
index d9cbb02b35a1..2882756c7084 100644
--- a/drivers/virtio/virtio_pci_legacy.c
+++ b/drivers/virtio/virtio_pci_legacy.c
@@ -90,7 +90,7 @@ static void vp_set_status(struct virtio_device *vdev, u8 status)
vp_legacy_set_status(&vp_dev->ldev, status);
}
-static void vp_reset(struct virtio_device *vdev)
+static int vp_reset(struct virtio_device *vdev)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
/* 0 status means a reset. */
@@ -100,6 +100,8 @@ static void vp_reset(struct virtio_device *vdev)
vp_legacy_get_status(&vp_dev->ldev);
/* Flush pending VQ/configuration callbacks. */
vp_synchronize_vectors(vdev);
+
+ return 0;
}
static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index 6d8ae2a6a8ca..4a6906a18cfa 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -21,6 +21,7 @@
#include "virtio_pci_common.h"
#define VIRTIO_AVQ_SGS_MAX 4
+#define VIRTIO_PCI_RESET_TIMEOUT_MS 1000
static void vp_get_features(struct virtio_device *vdev, u64 *features)
{
@@ -543,10 +544,11 @@ static void vp_set_status(struct virtio_device *vdev, u8 status)
vp_modern_avq_activate(vdev);
}
-static void vp_reset(struct virtio_device *vdev)
+static int vp_reset(struct virtio_device *vdev)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
+ int timeout = VIRTIO_PCI_RESET_TIMEOUT_MS;
/* 0 status means a reset. */
vp_modern_set_status(mdev, 0);
@@ -555,13 +557,20 @@ static void vp_reset(struct virtio_device *vdev)
* This will flush out the status write, and flush in device writes,
* including MSI-X interrupts, if any.
*/
- while (vp_modern_get_status(mdev))
- msleep(1);
+ while (vp_modern_get_status(mdev)) {
+ if (!timeout--) {
+ dev_warn(&vdev->dev, "reset timeout");
+ return -ETIMEDOUT;
+ }
+ msleep(1000);
+ }
vp_modern_avq_cleanup(vdev);
/* Flush pending VQ/configuration callbacks. */
vp_synchronize_vectors(vdev);
+
+ return 0;
}
static int vp_active_vq(struct virtqueue *vq, u16 msix_vec)
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index f923e42cfd01..568e1bd95e4c 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -212,7 +212,7 @@ void virtio_config_driver_enable(struct virtio_device *dev);
int virtio_device_freeze(struct virtio_device *dev);
int virtio_device_restore(struct virtio_device *dev);
#endif
-void virtio_reset_device(struct virtio_device *dev);
+int virtio_reset_device(struct virtio_device *dev);
void virtio_device_shutdown(struct virtio_device *dev);
int virtio_device_reset_prepare(struct virtio_device *dev);
int virtio_device_reset_done(struct virtio_device *dev);
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 69f84ea85d71..153426b0ae79 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -117,7 +117,7 @@ struct virtio_config_ops {
u32 (*generation)(struct virtio_device *vdev);
u8 (*get_status)(struct virtio_device *vdev);
void (*set_status)(struct virtio_device *vdev, u8 status);
- void (*reset)(struct virtio_device *vdev);
+ int (*reset)(struct virtio_device *vdev);
int (*find_vqs)(struct virtio_device *vdev, unsigned int nvqs,
struct virtqueue *vqs[],
struct virtqueue_info vqs_info[],
--
2.55.0