From 2bc6b218717b9d08f466f88209251d54bc09b207 Mon Sep 17 00:00:00 2001 From: Fuad Tabba Date: Tue, 22 Sep 2026 19:14:30 +0100 Subject: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2 __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 Reviewed-by: Anshuman Khandual Reviewed-by: Oliver Upton Signed-off-by: Will Deacon --- Documentation/admin-guide/abi-testing.rst | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 Documentation/admin-guide/abi-testing.rst (limited to 'Documentation/admin-guide/abi-testing.rst') 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: -- cgit v1.3.1