This patch-set fixes perf kvm commands issues, like missed memory
allocation check/free, out of range memory access and especially the
issue that fails to sample guest with "perf kvm record/top" commands on
Intel platforms.
The commit 634d36f82517 ("perf record: Just use "cycles:P" as the
default event") changes to use PEBS event to do sampling by default
including guest sampling. This breaks host to sample guest with commands
"perf kvm record/top" on Intel platforms.
Since the change "KVM: x86/pmu: Add basic support to enable guest PEBS
via DS"[1] starts, host loses the capability to sample guest with PEBS
since all PEBS related MSRs are switched to guest value after vm-entry,
like IA32_DS_AREA MSR is switched to guest GVA at vm-entry. This leads
to PEBS events can't be used to sample guest by host, otherwise no guest
PEBS records can be really sampled. The patches 4-5/5 fix this issue by
using "cycles" event instead of PEBS event "cycles:P" to sample guest on
Intel platforms.
Tests:
* Run command "perf kvm record -a && perf kvm report" and "perf kvm
top" on Intel Sapphire Rapids platform, guest records can be
captured successfully.
* Since no powerpc platforms on hand, doesn't check the patches on
powerpc. Any test on powerpc is appreciated.
Ref:
[1] https://lore.kernel.org/all/20220411101946.20262-1-likexu@tencent.com/
Dapeng Mi (5):
perf tools kvm: Add missed memory allocation check and free
perf tools kvm: Fix the potential out of range memory access issue
perf tools: Add helper x86__is_intel_cpu()
perf tools kvm: Use "cycles" to sample guest for "kvm record" on Intel
perf tools kvm: Use "cycles" to sample guest for "kvm top" on Intel
tools/perf/arch/x86/util/kvm-stat.c | 46 ++++++++++++++++++
tools/perf/builtin-kvm.c | 73 ++++++++++++++++++++++++-----
tools/perf/util/env.c | 22 +++++++++
tools/perf/util/env.h | 2 +
4 files changed, 131 insertions(+), 12 deletions(-)
base-commit: 6235ce77749f45cac27f630337e2fdf04e8a6c73
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2.34.1