linux-stable.git/drivers/virtio, branch v6.5.2

virtio-mem: check if the config changed before fake offlining memory

2023-08-10T19:51:46+00:00

If we repeatedly fail to fake offline memory to unplug it, we won't be
sending any unplug requests to the device. However, we only check if the
config changed when sending such (un)plug requests.

We could end up trying for a long time to unplug memory, even though
the config changed already and we're not supposed to unplug memory
anymore. For example, the hypervisor might detect a low-memory situation
while unplugging memory and decide to replug some memory. Continuing
trying to unplug memory in that case can be problematic.

So let's check on a more regular basis.

Signed-off-by: David Hildenbrand 
Message-Id: <20230713145551.2824980-5-david@redhat.com>
Signed-off-by: Michael S. Tsirkin

virtio-mem: keep retrying on offline_and_remove_memory() errors in Sub Block Mode (SBM)

2023-08-10T19:51:46+00:00

In case offline_and_remove_memory() fails in SBM, we leave a completely
unplugged Linux memory block stick around until we try plugging memory
again. We won't try removing that memory block again.

offline_and_remove_memory() may, for example, fail if we're racing with
another alloc_contig_range() user, if allocating temporary memory fails,
or if some memory notifier rejected the offlining request.

Let's handle that case better, by simple retrying to offline and remove
such memory.

Tested using CONFIG_MEMORY_NOTIFIER_ERROR_INJECT.

Signed-off-by: David Hildenbrand 
Message-Id: <20230713145551.2824980-4-david@redhat.com>
Signed-off-by: Michael S. Tsirkin

virtio-mem: convert most offline_and_remove_memory() errors to -EBUSY

2023-08-10T19:51:46+00:00

Just like we do with alloc_contig_range(), let's convert all unknown
errors to -EBUSY, but WARN so we can look into the issue. For example,
offline_pages() could fail with -EINTR, which would be unexpected in our
case.

Signed-off-by: David Hildenbrand 
Message-Id: <20230713145551.2824980-3-david@redhat.com>
Signed-off-by: Michael S. Tsirkin

virtio-mem: remove unsafe unplug in Big Block Mode (BBM)

2023-08-10T19:51:46+00:00

When "unsafe unplug" is enabled, we don't fake-offline all memory ahead of
actual memory offlining using alloc_contig_range(). Instead, we rely on
offline_pages() to also perform actual page migration, which might fail
or take a very long time.

In that case, it's possible to easily run into endless loops that cannot be
aborted anymore (as offlining is triggered by a workqueue then): For
example, a single (accidentally) permanently unmovable page in
ZONE_MOVABLE results in an endless loop. For ZONE_NORMAL, races between
isolating the pageblock (and checking for unmovable pages) and
concurrent page allocation are possible and similarly result in endless
loops.

The idea of the unsafe unplug mode was to make it possible to more
reliably unplug large memory blocks. However, (a) we really should be
tackling that differently, by extending the alloc_contig_range()-based
mechanism; and (b) this mode is not the default and as far as I know,
it's unused either way.

So let's simply get rid of it.

Signed-off-by: David Hildenbrand 
Message-Id: <20230713145551.2824980-2-david@redhat.com>
Signed-off-by: Michael S. Tsirkin

virtio-vdpa: Fix cpumask memory leak in virtio_vdpa_find_vqs()

2023-08-10T19:24:28+00:00

Free the cpumask allocated by create_affinity_masks() before returning
from the function.

Fixes: 3dad56823b53 ("virtio-vdpa: Support interrupt affinity spreading mechanism")
Signed-off-by: Gal Pressman 
Reviewed-by: Dragos Tatulea 
Message-Id: <20230726191036.14324-1-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin 
Acked-by: Jason Wang 
Reviewed-by: Xie Yongji

virtio-pci: Fix legacy device flag setting error in probe

2023-08-10T19:24:28+00:00

The 'is_legacy' flag is used to differentiate between legacy vs modern
device. Currently, it is based on the value of vp_dev->ldev.ioaddr.
However, due to the shared memory of the union between struct
virtio_pci_legacy_device and struct virtio_pci_modern_device, when
virtio_pci_modern_probe modifies the content of struct
virtio_pci_modern_device, it affects the content of struct
virtio_pci_legacy_device, and ldev.ioaddr is no longer zero, causing
the 'is_legacy' flag to be set as true. To resolve issue, when legacy
device is probed, mark 'is_legacy' as true, when modern device is
probed, keep 'is_legacy' as false.

Fixes: 4f0fc22534e3 ("virtio_pci: Optimize virtio_pci_device structure size")
Signed-off-by: Feng Liu 
Reviewed-by: Parav Pandit 
Reviewed-by: Jiri Pirko 
Message-Id: <20230719154550.79536-1-feliu@nvidia.com>
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Xuan Zhuo 
Acked-by: Jason Wang

virtio-mmio: don't break lifecycle of vm_dev

2023-08-10T19:24:27+00:00

vm_dev has a separate lifecycle because it has a 'struct device'
embedded. Thus, having a release callback for it is correct.

Allocating the vm_dev struct with devres totally breaks this protection,
though. Instead of waiting for the vm_dev release callback, the memory
is freed when the platform_device is removed. Resulting in a
use-after-free when finally the callback is to be called.

To easily see the problem, compile the kernel with
CONFIG_DEBUG_KOBJECT_RELEASE and unbind with sysfs.

The fix is easy, don't use devres in this case.

Found during my research about object lifetime problems.

Fixes: 7eb781b1bbb7 ("virtio_mmio: add cleanup for virtio_mmio_probe")
Signed-off-by: Wolfram Sang 
Message-Id: <20230629120526.7184-1-wsa+renesas@sang-engineering.com>
Signed-off-by: Michael S. Tsirkin

virtio: allow caller to override device DMA mask in vp_modern

2023-06-27T14:47:08+00:00

To add a bit of vendor flexibility with various virtio based devices,
allow the caller to specify a different DMA mask.  This adds a dma_mask
field to struct virtio_pci_modern_device.  If defined by the driver,
this mask will be used in a call to dma_set_mask_and_coherent() instead
of the traditional DMA_BIT_MASK(64).  This allows limiting the DMA space
on vendor devices with address limitations.

Signed-off-by: Shannon Nelson 
Acked-by: Jason Wang 
Message-Id: <20230519215632.12343-3-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin

virtio: allow caller to override device id in vp_modern

2023-06-27T14:47:08+00:00

To add a bit of vendor flexibility with various virtio based devices,
allow the caller to check for a different device id.  This adds a function
pointer field to struct virtio_pci_modern_device to specify an override
device id check.  If defined by the driver, this function will be called
to check that the PCI device is the vendor's expected device, and will
return the found device id to be stored in mdev->id.device.  This allows
vendors with alternative vendor device ids to use this library on their
own device BAR.

Note: A lot of the diff in this is simply indenting the existing code
into an else block.

Signed-off-by: Shannon Nelson 
Acked-by: Jason Wang 
Message-Id: <20230519215632.12343-2-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin

virtio_pci: Optimize virtio_pci_device structure size

2023-06-27T14:47:08+00:00

Improve the size of the virtio_pci_device structure, which is commonly
used to represent a virtio PCI device. A given virtio PCI device can
either of legacy type or modern type, with the
struct virtio_pci_legacy_device occupying 32 bytes and the
struct virtio_pci_modern_device occupying 88 bytes. Make them a union,
thereby save 32 bytes of memory as shown by the pahole tool. This
improvement is particularly beneficial when dealing with numerous
devices, as it helps conserve memory resources.

Before the modification, pahole tool reported the following:
struct virtio_pci_device {
[...]
        struct virtio_pci_legacy_device ldev;            /*   824    32 */
        /* --- cacheline 13 boundary (832 bytes) was 24 bytes ago --- */
        struct virtio_pci_modern_device mdev;            /*   856    88 */

        /* XXX last struct has 4 bytes of padding */
[...]
        /* size: 1056, cachelines: 17, members: 19 */
[...]
};

After the modification, pahole tool reported the following:
struct virtio_pci_device {
[...]
        union {
                struct virtio_pci_legacy_device ldev;    /*   824    32 */
                struct virtio_pci_modern_device mdev;    /*   824    88 */
        };                                               /*   824    88 */
[...]
	/* size: 1024, cachelines: 16, members: 18 */
[...]
};

Signed-off-by: Feng Liu 
Reviewed-by: Jiri Pirko 
Message-Id: <20230516135446.16266-1-feliu@nvidia.com>
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Xuan Zhuo 
Acked-by: Jason Wang