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H A D | nvme.c | 15a730e7 Fri Jul 23 19:58:43 GMT 2021 Philippe Mathieu-Daudé <philmd@redhat.com> block/nvme: Fix VFIO_MAP_DMA failed: No space left on device
When the NVMe block driver was introduced (see commit bdd6a90a9e5, January 2018), Linux VFIO_IOMMU_MAP_DMA ioctl was only returning -ENOMEM in case of error. The driver was correctly handling the error path to recycle its volatile IOVA mappings.
To fix CVE-2019-3882, Linux commit 492855939bdb ("vfio/type1: Limit DMA mappings per container", April 2019) added the -ENOSPC error to signal the user exhausted the DMA mappings available for a container.
The block driver started to mis-behave:
qemu-system-x86_64: VFIO_MAP_DMA failed: No space left on device (qemu) (qemu) info status VM status: paused (io-error) (qemu) c VFIO_MAP_DMA failed: No space left on device (qemu) c VFIO_MAP_DMA failed: No space left on device
(The VM is not resumable from here, hence stuck.)
Fix by handling the new -ENOSPC error (when DMA mappings are exhausted) without any distinction to the current -ENOMEM error, so we don't change the behavior on old kernels where the CVE-2019-3882 fix is not present.
An easy way to reproduce this bug is to restrict the DMA mapping limit (65535 by default) when loading the VFIO IOMMU module:
# modprobe vfio_iommu_type1 dma_entry_limit=666
Cc: qemu-stable@nongnu.org Cc: Fam Zheng <fam@euphon.net> Cc: Maxim Levitsky <mlevitsk@redhat.com> Cc: Alex Williamson <alex.williamson@redhat.com> Reported-by: Michal Prívozník <mprivozn@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20210723195843.1032825-1-philmd@redhat.com Fixes: bdd6a90a9e5 ("block: Add VFIO based NVMe driver") Buglink: https://bugs.launchpad.net/qemu/+bug/1863333 Resolves: https://gitlab.com/qemu-project/qemu/-/issues/65 Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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