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/tools/rtla/rtla-timerlat.rst | 54 ++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 Documentation/tools/rtla/rtla-timerlat.rst (limited to 'Documentation/tools/rtla/rtla-timerlat.rst') diff --git a/Documentation/tools/rtla/rtla-timerlat.rst b/Documentation/tools/rtla/rtla-timerlat.rst new file mode 100644 index 000000000..63718c52a --- /dev/null +++ b/Documentation/tools/rtla/rtla-timerlat.rst @@ -0,0 +1,54 @@ +================ +rtla-timerlat +================ +------------------------------------------- +Measures the operating system timer latency +------------------------------------------- + +:Manual section: 1 + +SYNOPSIS +======== +**rtla timerlat** [*MODE*] ... + +DESCRIPTION +=========== + +.. include:: common_timerlat_description.txt + +The **rtla timerlat top** mode displays a summary of the periodic output +from the *timerlat* tracer. The **rtla timerlat hist** mode displays +a histogram of each tracer event occurrence. For further details, please +refer to the respective man page. + +MODES +===== +**top** + + Prints the summary from *timerlat* tracer. + +**hist** + + Prints a histogram of timerlat samples. + +If no *MODE* is given, the top mode is called, passing the arguments. + +OPTIONS +======= +**-h**, **--help** + + Display the help text. + +For other options, see the man page for the corresponding mode. + +SEE ALSO +======== +**rtla-timerlat-top**\(1), **rtla-timerlat-hist**\(1) + +`Timerlat tracer `__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira + +.. include:: common_appendix.txt -- cgit v1.3.1