Andi Kleen 9b545c04ab perf/x86/kvm: Avoid unnecessary work in guest filtering ... KVM added a workaround for PEBS events leaking into guests with commit: 26a4f3c08d ("perf/x86: disable PEBS on a guest entry.") This uses the VT entry/exit list to add an extra disable of the PEBS_ENABLE MSR. Intel also added a fix for this issue to microcode updates on Haswell/Broadwell/Skylake. It turns out using the MSR entry/exit list makes VM exits significantly slower. The list is only needed for disabling PEBS, because the GLOBAL_CTRL change gets optimized by KVM into changing the VMCS. Check for the microcode updates that have the microcode fix for leaking PEBS, and disable the extra entry/exit list entry for PEBS_ENABLE. In addition we always clear the GLOBAL_CTRL for the PEBS counter while running in the guest, which is enough to make them never fire at the wrong side of the host/guest transition. The overhead for VM exits with the filtering active with the patch is reduced from 8% to 4%. The microcode patch has already been merged into future platforms. This patch is one-off thing. The quirks is used here. For other old platforms which doesn't have microcode patch and quirks, extra disable of the PEBS_ENABLE MSR is still required. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: bp@alien8.de Link: https://lkml.kernel.org/r/1549319013-4522-2-git-send-email-kan.liang@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>		2019-02-11 08:00:39 +01:00
..
amd	perf/core, arch/x86: Strengthen exclusion checks with PERF_PMU_CAP_NO_EXCLUDE	2019-01-21 11:01:29 +01:00
intel	perf/x86/kvm: Avoid unnecessary work in guest filtering	2019-02-11 08:00:39 +01:00
core.c	perf/x86/intel: Move branch tracing setup to the Intel-specific source file	2018-11-22 09:45:09 +01:00
Kconfig	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
Makefile	perf/x86/events: Add an AMD-specific Makefile	2017-01-30 12:01:19 +01:00
msr.c	perf/core, arch/x86: Use PERF_PMU_CAP_NO_EXCLUDE for exclusion incapable PMUs	2019-01-21 11:01:27 +01:00
perf_event.h	perf/x86/kvm: Avoid unnecessary work in guest filtering	2019-02-11 08:00:39 +01:00