[PATCH v7 12/41] KVM: arm64: gic-v5: Sanitize ID_AA64PFR2_EL1.GCIE

[Mark Brown]

On Thu, Mar 19, 2026 at 03:52:50PM +0000, Sascha Bischoff wrote:
> Add in a sanitization function for ID_AA64PFR2_EL1, preserving the
> already-present behaviour for the FPMR, MTEFAR, and MTESTOREONLY
> fields. Add sanitisation for the GCIE field, which is set to IMP if
> the host supports a GICv5 guest and NI, otherwise.

...

> All of this extra work is required to make sure that "legacy" GICv3
> guests based on QEMU transparently work on compatible GICv5 hosts
> without modification.

I'm seeing a regression in -next in set_id_regs on a range of platforms,
including physical ones like the Toradex Verdin AM62 and i.MX8MP-EVK,
with a GICv3:

# ok 105 # SKIP MTE capability not supported, nothing to test
# ==== Test Assertion Failure ====
#   arm64/set_id_regs.c:651: test_reg_vals[encoding_to_range_idx(uc.args[2])] == uc.args[3]
#   pid=3573 tid=3573 errno=4 - Interrupted system call
#      1	0x0000000000403047: test_guest_reg_read at set_id_regs.c:651
#      2	0x00000000004024cb: main at set_id_regs.c:805
#      3	0x0000ffff9e85251b: ?? ??:0
#      4	0x0000ffff9e8525fb: ?? ??:0
#      5	0x00000000004027af: _start at ??:?
#   0x1111 != 0x1001111 (test_reg_vals[encoding_to_range_idx(uc.args[2])] != uc.args[3])
not ok 20 selftests: kvm: set_id_regs # exit=254

Platforms without a GICv3 appear unaffected.

Full log:

   https://lava.sirena.org.uk/scheduler/job/2584795#L4111

bisect log:

# bad: [0ec822710d040a1e4a13be04494dc9f0462f8ba7] Merge branch 'for-linux-next-fixes' of https://gitlab.freedesktop.org/drm/misc/kernel.git
# good: [0e4f8f1a3d081e834be5fd0a62bdb2554fadd307] Merge tag 'parisc-for-7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
# good: [09e70e4f119ff650d24c96161fd2f62ac7e424b0] regmap: Synchronize cache for the page selector
git bisect start '0ec822710d040a1e4a13be04494dc9f0462f8ba7' '0e4f8f1a3d081e834be5fd0a62bdb2554fadd307' '09e70e4f119ff650d24c96161fd2f62ac7e424b0'
# test job: [09e70e4f119ff650d24c96161fd2f62ac7e424b0] https://lava.sirena.org.uk/scheduler/job/2565604
# test job: [0ec822710d040a1e4a13be04494dc9f0462f8ba7] https://lava.sirena.org.uk/scheduler/job/2584795
# bad: [0ec822710d040a1e4a13be04494dc9f0462f8ba7] Merge branch 'for-linux-next-fixes' of https://gitlab.freedesktop.org/drm/misc/kernel.git
git bisect bad 0ec822710d040a1e4a13be04494dc9f0462f8ba7
# test job: [a5d4dfaac4b2810ec2be80d2a9a1facce7dc554d] https://lava.sirena.org.uk/scheduler/job/2584889
# good: [a5d4dfaac4b2810ec2be80d2a9a1facce7dc554d] Merge branch 'mtd/fixes' of https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git
git bisect good a5d4dfaac4b2810ec2be80d2a9a1facce7dc554d
# test job: [d04c0e637ff3323b010804dbfe349fb9c1309253] https://lava.sirena.org.uk/scheduler/job/2585075
# bad: [d04c0e637ff3323b010804dbfe349fb9c1309253] Merge branch 'dma-mapping-fixes' of https://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux.git
git bisect bad d04c0e637ff3323b010804dbfe349fb9c1309253
# test job: [e3d585ed3ff891a00c2284fef4be9cf8581735ab] https://lava.sirena.org.uk/scheduler/job/2585150
# bad: [e3d585ed3ff891a00c2284fef4be9cf8581735ab] Merge branch kvm-arm64/vgic-v5-ppi into kvmarm-master/next
git bisect bad e3d585ed3ff891a00c2284fef4be9cf8581735ab
# test job: [0a9f38bf612b195e04236d366ed9f769ce14cc27] https://lava.sirena.org.uk/scheduler/job/2585330
# bad: [0a9f38bf612b195e04236d366ed9f769ce14cc27] KVM: arm64: selftests: Introduce a minimal GICv5 PPI selftest
git bisect bad 0a9f38bf612b195e04236d366ed9f769ce14cc27
# test job: [4d591252bacb2d004b7c7f5db439bfa23b552ee7] https://lava.sirena.org.uk/scheduler/job/2585661
# bad: [4d591252bacb2d004b7c7f5db439bfa23b552ee7] KVM: arm64: gic-v5: Implement PPI interrupt injection
git bisect bad 4d591252bacb2d004b7c7f5db439bfa23b552ee7
# test job: [da92ff15ca4c5b0f75ec1cb3d2e275db2ff2c810] https://lava.sirena.org.uk/scheduler/job/2585906
# good: [da92ff15ca4c5b0f75ec1cb3d2e275db2ff2c810] KVM: arm64: gic-v5: Add Arm copyright header
git bisect good da92ff15ca4c5b0f75ec1cb3d2e275db2ff2c810
# test job: [070543a85adce329672012a1fe35fa48c76e02d5] https://lava.sirena.org.uk/scheduler/job/2586294
# bad: [070543a85adce329672012a1fe35fa48c76e02d5] KVM: arm64: gic-v5: Trap and emulate ICC_IDR0_EL1 accesses
git bisect bad 070543a85adce329672012a1fe35fa48c76e02d5
# test job: [a258a383b91774ac646517ec1003a442964d8946] https://lava.sirena.org.uk/scheduler/job/2586455
# bad: [a258a383b91774ac646517ec1003a442964d8946] KVM: arm64: gic-v5: Sanitize ID_AA64PFR2_EL1.GCIE
git bisect bad a258a383b91774ac646517ec1003a442964d8946
# test job: [f656807150e3e1c6f76cab918e5adfad6d881d58] https://lava.sirena.org.uk/scheduler/job/2586592
# good: [f656807150e3e1c6f76cab918e5adfad6d881d58] KVM: arm64: gic-v5: Detect implemented PPIs on boot
git bisect good f656807150e3e1c6f76cab918e5adfad6d881d58
# first bad commit: [a258a383b91774ac646517ec1003a442964d8946] KVM: arm64: gic-v5: Sanitize ID_AA64PFR2_EL1.GCIE
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20260323/5653e33f/attachment.sig>