To pick up the changes in:
765a0542fd ("x86/virt/tdx: Detect TDX during kernel boot")
Addressing this tools/perf build warning:
Warning: Kernel ABI header differences:
diff -u tools/arch/x86/include/asm/msr-index.h arch/x86/include/asm/msr-index.h
That makes the beautification scripts to pick some new entries:
$ tools/perf/trace/beauty/tracepoints/x86_msr.sh > before
$ cp arch/x86/include/asm/msr-index.h tools/arch/x86/include/asm/msr-index.h
$ tools/perf/trace/beauty/tracepoints/x86_msr.sh > after
$ diff -u before after
--- before 2024-01-25 11:08:12.363223880 -0300
+++ after 2024-01-25 11:08:24.839307699 -0300
@@ -21,6 +21,7 @@
[0x0000004f] = "PPIN",
[0x00000060] = "LBR_CORE_TO",
[0x00000079] = "IA32_UCODE_WRITE",
+ [0x00000087] = "IA32_MKTME_KEYID_PARTITIONING",
[0x0000008b] = "AMD64_PATCH_LEVEL",
[0x0000008C] = "IA32_SGXLEPUBKEYHASH0",
[0x0000008D] = "IA32_SGXLEPUBKEYHASH1",
$
Now one can trace systemwide asking to see backtraces to where that MSR
is being read/written, see this example with a previous update:
# perf trace -e msr:*_msr/max-stack=32/ --filter="msr==IA32_MKTME_KEYID_PARTITIONING"
^C#
If we use -v (verbose mode) we can see what it does behind the scenes:
# perf trace -v -e msr:*_msr/max-stack=32/ --filter="msr==IA32_MKTME_KEYID_PARTITIONING"
Using CPUID GenuineIntel-6-8E-A
0x87
New filter for msr:read_msr: (msr==0x87) && (common_pid != 58627 && common_pid != 3792)
0x87
New filter for msr:write_msr: (msr==0x87) && (common_pid != 58627 && common_pid != 3792)
mmap size 528384B
^C#
Example with a frequent msr:
# perf trace -v -e msr:*_msr/max-stack=32/ --filter="msr==IA32_SPEC_CTRL" --max-events 2
Using CPUID AuthenticAMD-25-21-0
0x48
New filter for msr:read_msr: (msr==0x48) && (common_pid != 2612129 && common_pid != 3841)
0x48
New filter for msr:write_msr: (msr==0x48) && (common_pid != 2612129 && common_pid != 3841)
mmap size 528384B
Looking at the vmlinux_path (8 entries long)
symsrc__init: build id mismatch for vmlinux.
Using /proc/kcore for kernel data
Using /proc/kallsyms for symbols
0.000 Timer/2525383 msr:write_msr(msr: IA32_SPEC_CTRL, val: 6)
do_trace_write_msr ([kernel.kallsyms])
do_trace_write_msr ([kernel.kallsyms])
__switch_to_xtra ([kernel.kallsyms])
__switch_to ([kernel.kallsyms])
__schedule ([kernel.kallsyms])
schedule ([kernel.kallsyms])
futex_wait_queue_me ([kernel.kallsyms])
futex_wait ([kernel.kallsyms])
do_futex ([kernel.kallsyms])
__x64_sys_futex ([kernel.kallsyms])
do_syscall_64 ([kernel.kallsyms])
entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
__futex_abstimed_wait_common64 (/usr/lib64/libpthread-2.33.so)
0.030 :0/0 msr:write_msr(msr: IA32_SPEC_CTRL, val: 2)
do_trace_write_msr ([kernel.kallsyms])
do_trace_write_msr ([kernel.kallsyms])
__switch_to_xtra ([kernel.kallsyms])
__switch_to ([kernel.kallsyms])
__schedule ([kernel.kallsyms])
schedule_idle ([kernel.kallsyms])
do_idle ([kernel.kallsyms])
cpu_startup_entry ([kernel.kallsyms])
secondary_startup_64_no_verify ([kernel.kallsyms])
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kai Huang <kai.huang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/ZbJt27rjkQVU1YoP@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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