KVM: arm64: vgic-its: Skip unreachable devices instead of failing the save

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vgic_its_save_device_tables() aborts with -EINVAL when a device's entry
falls outside the device table, which a guest can arrange on its own: an
indirect table lets it clear an L1 entry's valid bit without touching
GITS_BASER. That fails a save userspace should be able to issue
reliably.

Skip the device instead, and point the saved DTE chain past it, as
commit ad1e686e23 ("KVM: arm64: vgic-its: Point saved ITEs at the
next valid entry") does for ITEs. compute_next_devid_offset() takes the
next device off the list whether or not it was saved, so the predecessor
would otherwise point at an entry the save never wrote. Restore follows
that offset while it stays inside the table being scanned: within an L2
block, or anywhere in a flat table. Both need userspace to remove a
memslot under the table, since dropping an L1 entry takes the whole
block with it and scan_its_table() stops at the block boundary.

Fixes: 57a9a11715 ("KVM: arm64: vgic-its: Device table save/restore")
Suggested-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/all/86bjaz5s6v.wl-maz@kernel.org/
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://patch.msgid.link/20260821064445.615838-4-fuad.tabba@linux.dev
Signed-off-by: Oliver Upton <oupton@kernel.org>

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Fuad Tabba 2026-08-21 07:44:44 +01:00 • committed by Oliver Upton

parent 30908e7272

commit cc5d96036e

1 changed files with 19 additions and 13 deletions

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arch/arm64/kvm/vgic/vgic-its.c

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