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| author | Madhavan Srinivasan <maddy@linux.vnet.ibm.com> | 2019-11-18 04:44:52 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-12-05 07:06:40 +0100 |
| commit | 249fad734a25889a4f23ed014d43634af6798063 (patch) | |
| tree | aa148af2d2dde458e06d3dd42cbe393d6a39c387 /arch/powerpc | |
| parent | powerpc/powernv: Avoid re-registration of imc debugfs directory (diff) | |
| download | linux-249fad734a25889a4f23ed014d43634af6798063.tar.xz linux-249fad734a25889a4f23ed014d43634af6798063.zip | |
powerpc/perf: Disable trace_imc pmu
When a root user or a user with CAP_SYS_ADMIN privilege uses any
trace_imc performance monitoring unit events, to monitor application
or KVM threads, it may result in a checkstop (System crash).
The cause is frequent switching of the "trace/accumulation" mode of
the In-Memory Collection hardware (LDBAR).
This patch disables the trace_imc PMU unit entirely to avoid
triggering the checkstop. A future patch will reenable it at a later
stage once a workaround has been developed.
Fixes: 012ae244845f ("powerpc/perf: Trace imc PMU functions")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Tested-by: Hariharan T.S. <hari@linux.ibm.com>
[mpe: Add pr_info_once() so dmesg shows the PMU has been disabled]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191118034452.9939-1-maddy@linux.vnet.ibm.com
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/platforms/powernv/opal-imc.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c index 3b4518f4b643..000b350d4060 100644 --- a/arch/powerpc/platforms/powernv/opal-imc.c +++ b/arch/powerpc/platforms/powernv/opal-imc.c @@ -278,7 +278,14 @@ static int opal_imc_counters_probe(struct platform_device *pdev) domain = IMC_DOMAIN_THREAD; break; case IMC_TYPE_TRACE: - domain = IMC_DOMAIN_TRACE; + /* + * FIXME. Using trace_imc events to monitor application + * or KVM thread performance can cause a checkstop + * (system crash). + * Disable it for now. + */ + pr_info_once("IMC: disabling trace_imc PMU\n"); + domain = -1; break; default: pr_warn("IMC Unknown Device type \n"); |