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/security/lsm-development.rst | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) create mode 100644 Documentation/security/lsm-development.rst (limited to 'Documentation/security/lsm-development.rst') diff --git a/Documentation/security/lsm-development.rst b/Documentation/security/lsm-development.rst new file mode 100644 index 000000000..5895e529d --- /dev/null +++ b/Documentation/security/lsm-development.rst @@ -0,0 +1,17 @@ +================================= +Linux Security Module Development +================================= + +Based on https://lore.kernel.org/r/20071026073721.618b4778@laptopd505.fenrus.org, +a new LSM is accepted into the kernel when its intent (a description of +what it tries to protect against and in what cases one would expect to +use it) has been appropriately documented in ``Documentation/admin-guide/LSM/``. +This allows an LSM's code to be easily compared to its goals, and so +that end users and distros can make a more informed decision about which +LSMs suit their requirements. + +For extensive documentation on the available LSM hook interfaces, please +see ``security/security.c`` and associated structures: + +.. kernel-doc:: security/security.c + :export: -- cgit v1.3.1