From: Fuad Tabba <fuad.tabba@linux.dev> mainline inclusion from mainline-v7.3-rc1 commit c6c156d931c33b92362383cf76f6d6e1291dcbfe category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19092 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- MAPC with V=0 drops ite->collection but leaves the ITE on the device's ITT list, and vgic_its_save_ite() dereferences it unconditionally. A guest that issues MAPD, MAPTI and then MAPC(V=0) therefore oopses the host when the VMM issues KVM_DEV_ARM_ITS_SAVE_TABLES to migrate it. That sequence is UNPREDICTABLE per the architecture, but KVM already handles the resulting state in the translate, MOVI and DISCARD paths. Save a zeroed entry, which vgic_its_restore_ite() reads back as invalid. Skipping the ITE instead would leave the ITT slot holding whatever is in guest memory, and restore rejects an entry naming a collection the restored collection table does not have. Fixes: eff484e0298da ("KVM: arm64: vgic-its: ITT save and restore") Cc: stable@vger.kernel.org Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev> Link: https://patch.msgid.link/20260807104102.2410744-2-fuad.tabba@linux.dev Signed-off-by: Oliver Upton <oupton@kernel.org> Conflicts: arch/arm64/kvm/vgic/vgic-its.c [ 3b2c81d5feb2 ("KVM: arm64: vgic-its: Add stronger type-checking to the ITS entry sizes") not merged] Signed-off-by: Zhang Kunbo <zhangkunbo@huawei.com> --- arch/arm64/kvm/vgic/vgic-its.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index acf611bc6f7e..c76591f17a1c 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -2234,6 +2234,14 @@ static int vgic_its_save_ite(struct vgic_its *its, struct its_device *dev, u32 next_offset; u64 val; + /* + * MAPC with V=0 keeps the ITEs mapped but drops their collection, + * and with it the ICID. Save a zeroed entry, which the restore path + * reads back as invalid. + */ + if (!ite->collection) + return vgic_its_write_entry_lock(its, gpa, 0ULL, ite_esz); + next_offset = compute_next_eventid_offset(&dev->itt_head, ite); val = ((u64)next_offset << KVM_ITS_ITE_NEXT_SHIFT) | ((u64)ite->irq->intid << KVM_ITS_ITE_PINTID_SHIFT) | -- 2.34.1