From: Michael Petlan <mpetlan@redhat.com>
To: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Ian Rogers <irogers@google.com>,
Dapeng Mi <dapeng1.mi@linux.intel.com>,
James Clark <james.clark@linaro.org>,
Sadasivan Shaiju <sadasivan.shaiju2@amd.com>,
x86@kernel.org, linux-perf-users@vger.kernel.org,
linux-kernel@vger.kernel.org,
Manali Shukla <manali.shukla@amd.com>,
Santosh Shukla <santosh.shukla@amd.com>,
Ananth Narayan <ananth.narayan@amd.com>,
Sandipan Das <sandipan.das@amd.com>
Subject: Re: [PATCH v2 4/5] perf/amd/ibs: Avoid calling perf_allow_kernel() from the IBS NMI handler
Date: Mon, 9 Mar 2026 20:06:56 +0100 (CET) [thread overview]
Message-ID: <21f41878-254f-191e-eaa9-26a9faf68d45@redhat.com> (raw)
In-Reply-To: <9145b8b7-fb83-49c4-aa17-acdba069359a@amd.com>
On Mon, 9 Mar 2026, Ravi Bangoria wrote:
> Hi Michael,
>
> > By evaluating the privileges at the event-init moment and using cached
> > value later, couldn't it lead to the cached value being obsolete at
> > some point? E.g. a setuid program later dropping the privileges but
> > still being able to read physical addresses?
>
> Yes, but wouldn't the same concern apply to all other call sites of
> perf_allow_kernel() ?
Well, I don't say this case is worse than the others, just raising a
more generic question whether this design is fairly acceptable or would
deserve e.g. privilege adjusting at the time when they are dropped or
something... Nothing more, just a note... :)
Michael
>
> Thanks,
> Ravi
>
>
next prev parent reply other threads:[~2026-03-09 19:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-16 4:22 [PATCH v2 0/5] perf/amd/ibs: Assorted fixes Ravi Bangoria
2026-02-16 4:22 ` [PATCH v2 1/5] perf/amd/ibs: Account interrupt for discarded samples Ravi Bangoria
2026-02-23 12:25 ` Michael Petlan
2026-02-24 8:11 ` Ravi Bangoria
2026-02-26 13:06 ` Peter Zijlstra
2026-02-28 10:56 ` [tip: perf/core] " tip-bot2 for Ravi Bangoria
2026-02-16 4:22 ` [PATCH v2 2/5] perf/amd/ibs: Limit ldlat->l3missonly dependency to Zen5 Ravi Bangoria
2026-02-28 10:56 ` [tip: perf/core] " tip-bot2 for Ravi Bangoria
2026-02-16 4:22 ` [PATCH v2 3/5] perf/amd/ibs: Preserve PhyAddrVal bit when clearing PhyAddr MSR Ravi Bangoria
2026-02-28 10:56 ` [tip: perf/core] " tip-bot2 for Ravi Bangoria
2026-02-16 4:22 ` [PATCH v2 4/5] perf/amd/ibs: Avoid calling perf_allow_kernel() from the IBS NMI handler Ravi Bangoria
2026-02-28 10:56 ` [tip: perf/core] " tip-bot2 for Ravi Bangoria
2026-03-06 21:13 ` [PATCH v2 4/5] " Michael Petlan
2026-03-09 9:07 ` Michael Petlan
2026-03-09 11:40 ` Ravi Bangoria
2026-03-09 19:06 ` Michael Petlan [this message]
2026-03-10 16:46 ` Ravi Bangoria
2026-02-16 4:22 ` [PATCH v2 5/5] perf/amd/ibs: Avoid race between event add and NMI Ravi Bangoria
2026-02-28 10:56 ` [tip: perf/core] " tip-bot2 for Ravi Bangoria
2026-02-18 5:51 ` [PATCH v2 0/5] perf/amd/ibs: Assorted fixes Namhyung Kim
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