From: Peter Zijlstra <peterz@infradead.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Xin Li <xin@zytor.com>, Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Sean Christopherson <seanjc@google.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
Tony Luck <tony.luck@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Zhang Rui <rui.zhang@intel.com>,
Lukasz Luba <lukasz.luba@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Brian Gerst <brgerst@gmail.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Jacob Pan <jacob.pan@linux.microsoft.com>,
Andi Kleen <ak@linux.intel.com>, Kai Huang <kai.huang@intel.com>,
Nikolay Borisov <nik.borisov@suse.com>,
linux-perf-users@vger.kernel.org, linux-edac@vger.kernel.org,
kvm@vger.kernel.org, linux-pm@vger.kernel.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH v5 5/9] x86/nmi: Add support to handle NMIs with source information
Date: Thu, 8 May 2025 22:49:06 +0200 [thread overview]
Message-ID: <20250508204906.GJ4439@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <D368D488-6D4E-4590-8E98-A7D7CD5E7F20@zytor.com>
On Thu, May 08, 2025 at 01:23:04PM -0700, H. Peter Anvin wrote:
> On May 8, 2025 5:15:44 AM PDT, Peter Zijlstra <peterz@infradead.org> wrote:
> >> Looks good, except when fred_event_data() returns 0. I don't expect it
> >> to happen in practice. But, maybe with new hardware and eventually
> >> different hypervisors being involved, it is a possibility.
> >>
> >> We can either call it a bug that an NMI happened without source
> >> information. Or be extra nice and do this:
> >>
> >> if (cpu_feature_enabled(X86_FEATURE_NMI_SOURCE) && type == NMI_LOCAL) {
> >> source = fred_event_data(regs);
> >> if (!source || (source & BIT(0)))
> >> source = ~0UL;
> >> }
> >
> >Perhaps also WARN about the !source case?
>
> A 0 should be interpreted such that NMI source is not available, e.g.
> due to a broken hypervisor or similar.
I'm reading that as an agreement for WARN-ing on 0. We should definitely
WARN on broken hypervisors and similar.
next prev parent reply other threads:[~2025-05-08 20:49 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-07 1:21 [PATCH v5 0/9] x86: Add support for NMI-source reporting with FRED Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 1/9] x86/fred, KVM: VMX: Pass event data to the FRED entry point from KVM Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 2/9] x86/cpufeatures: Add the CPUID feature bit for NMI-source reporting Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 3/9] x86/nmi: Extend the registration interface to include the NMI-source vector Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 4/9] x86/nmi: Assign and register NMI-source vectors Sohil Mehta
2025-05-07 8:22 ` Peter Zijlstra
2025-05-07 20:43 ` Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 5/9] x86/nmi: Add support to handle NMIs with source information Sohil Mehta
2025-05-07 9:14 ` Peter Zijlstra
2025-05-07 21:48 ` Sohil Mehta
2025-05-08 12:15 ` Peter Zijlstra
2025-05-08 20:23 ` H. Peter Anvin
2025-05-08 20:49 ` Peter Zijlstra [this message]
2025-05-09 0:45 ` Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 6/9] x86/nmi: Prepare for the new NMI-source vector encoding Sohil Mehta
2025-05-07 9:17 ` Peter Zijlstra
2025-05-07 22:10 ` Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 7/9] x86/nmi: Enable NMI-source for IPIs delivered as NMIs Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 8/9] perf/x86: Enable NMI-source reporting for perfmon Sohil Mehta
2025-05-08 11:20 ` Sandipan Das
2025-05-09 0:46 ` Sohil Mehta
2025-05-07 1:21 ` [PATCH v5 9/9] x86/nmi: Include NMI-source information in tracepoint and debug prints Sohil Mehta
2025-05-07 21:48 ` Steven Rostedt
2025-05-08 0:02 ` Sohil Mehta
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