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| author | Fuad Tabba <fuad.tabba@linux.dev> | 2026-09-22 19:14:30 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2026-09-23 12:34:30 +0000 |
| commit | 2bc6b218717b9d08f466f88209251d54bc09b207 (patch) | |
| tree | cb91c941eccb15f94cbec4e96aa3a9c8736b5d66 /Documentation/admin-guide/abi-testing.rst | |
| download | linux-stable-2bc6b218717b9d08f466f88209251d54bc09b207.tar.gz linux-stable-2bc6b218717b9d08f466f88209251d54bc09b207.zip | |
arm64/boot: Disable trapping of PMZR_EL0 writes to EL2grafted
__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.
PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in
HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host
traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The
kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU
driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a
write from EL0 reaches the trap and takes the host down without a panic
message.
Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already
does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9
bits.
Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9")
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'Documentation/admin-guide/abi-testing.rst')
| -rw-r--r-- | Documentation/admin-guide/abi-testing.rst | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/admin-guide/abi-testing.rst b/Documentation/admin-guide/abi-testing.rst new file mode 100644 index 000000000..6153ebd38 --- /dev/null +++ b/Documentation/admin-guide/abi-testing.rst @@ -0,0 +1,22 @@ +.. SPDX-License-Identifier: GPL-2.0 + +ABI testing symbols +=================== + +Documents interfaces that are felt to be stable, +as the main development of this interface has been completed. + +The interface can be changed to add new features, but the +current interface will not break by doing this, unless grave +errors or security problems are found in them. + +Userspace programs can start to rely on these interfaces, but they must +be aware of changes that can occur before these interfaces move to +be marked stable. + +Programs that use these interfaces are strongly encouraged to add their +name to the description of these interfaces, so that the kernel +developers can easily notify them if any changes occur. + +.. kernel-abi:: testing + :no-files: |