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/[email protected]/ Signed-off-by: Radu Rendec <[email protected]> --- 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
