Add more resiliency to disk image format handling by rbradford · Pull Request #7728 · cloud-hypervisor/cloud-hypervisor · GitHub
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Add more resiliency to disk image format handling#7728

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likebreath merged 4 commits intocloud-hypervisor:mainfrom
rbradford:202602/image-type-resiliency
Feb 19, 2026
Merged

Add more resiliency to disk image format handling#7728
likebreath merged 4 commits intocloud-hypervisor:mainfrom
rbradford:202602/image-type-resiliency

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  • vmm: Improve resiliency of image type handling
  • vmm, virtio-devices: Deny zero sector writes for autodetected raw images
  • vhost_user_blk: Disable use of backing files in test implementation
  • virtio-devices, block: Reject sector 0 discard/"write zeroes" requests

@rbradford rbradford requested a review from a team as a code owner February 19, 2026 20:13
@likebreath likebreath force-pushed the 202602/image-type-resiliency branch 2 times, most recently from 1a11d53 to 3cb6aac Compare February 19, 2026 21:10
Add an image_type to DiskConfig to specify the image type. If none is
specified autodetect the image type but disable potentially unsafe
behaviour in the QCOW2 backend by disabling the backing file support.

If the image type is autodetected then fix it in the config so that it
will be persistant across reboots and migrations/snapshot & restores.
This also handles the case where the image type was not specified as
part of the disk configuration.

Signed-off-by: Rob Bradford <rbradford@meta.com>
If the disk image was autodetected to raw (not specified with image_type
= 0) then in the virtio-block subsystem generate errors for writes to
block 0 (treat as if read-only). This gives an immediate error vs using
the image implementations in the block subsystem.

Signed-off-by: Rob Bradford <rbradford@meta.com>
Remove the use of QCOW2 backing files in the test implementation used
for CI.

Signed-off-by: Rob Bradford <rbradford@meta.com>
As well as rejecting writes to sector 0 in the case of raw files where
the user hasn't specified the image_type also reject virtio requests of
type discard and write_zeroes.

Signed-off-by: Rob Bradford <rbradford@meta.com>
@rbradford rbradford force-pushed the 202602/image-type-resiliency branch from 3cb6aac to a33bfb4 Compare February 19, 2026 21:48
@likebreath likebreath enabled auto-merge February 19, 2026 22:37
@likebreath likebreath added this pull request to the merge queue Feb 19, 2026
Merged via the queue into cloud-hypervisor:main with commit a63315d Feb 19, 2026
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2 participants