From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E74F047D928 for ; Thu, 8 Jan 2026 13:54:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767880452; cv=none; b=r6YMwHrOc5zrdaQvkNUg7DdjKvc3sQJ4/9Iq/Iz44rFj0CO3MH/kwFWWfh+IMcunK4HjeIs3gN8b0RMt+b8FVFaNiD0/Cxzz+xnk27kdjRftJGMJX2eAVtm6TJwdyM/q8pHM24Rm3JWzW++Nt4I0CcOT97h8Yzef05ff0esDqTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767880452; c=relaxed/simple; bh=cuQ2dPAO2JBpXVAxUbPVmACLuq/If4emBH+mP+jKAQE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gvaHhaXGZOvS48GdXycWMzIsp3r7zcwG65FxYsmc0Y2fPKte9btU9bwsWkdnSEGtdjfEPMvS5+qQwiCDJYJqn5zPUuQLk6w++YiI6gU/Avh5JTg5j+n9eASwdckGgPiIOWKjMbzj+r74vje3lVSj8nCPiK8DKzyyCXyCeLVydew= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=YvxsTmol; arc=none smtp.client-ip=91.218.175.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="YvxsTmol" Message-ID: <72a635cb-05c7-47d2-84aa-4d82d1e0aebd@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1767880444; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Jh/13QNGjy5fh8wgOgf8HymnWSbTi33cjlQA9koC/94=; b=YvxsTmolbA5Wh006Ic/eDgN5Y8b8wMd+GNxCbgYGADxMD56bjxULHCu+vf6mXH4k2YLauU NVET58bUTHjTlxu+mGw7H0XewJd3EQNea4b2nJ9pE7OcATnbwHJOe+h7Bq6x9O1V71iJ0N 6Ywbx67nFoyJaggMc0o18MxQpqeQAqw= Date: Thu, 8 Jan 2026 21:53:46 +0800 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 6.6.y 0/4] perf/x86/amd: add LBR capture support outside of hardware events To: Greg KH Cc: stable@vger.kernel.org, Andrii Nakryiko , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260102090320.32843-1-leon.hwang@linux.dev> <2026010809-matchless-reporter-3129@gregkh> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Leon Hwang In-Reply-To: <2026010809-matchless-reporter-3129@gregkh> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 2026/1/8 19:11, Greg KH wrote: > On Fri, Jan 02, 2026 at 05:03:16PM +0800, Leon Hwang wrote: >> Hi all, >> >> This backport wires up AMD perfmon v2 so BPF and other software clients >> can snapshot LBR stacks on demand, similar to the Intel support >> upstream. The series keeps the LBR-freeze path branchless, adds the >> perf_snapshot_branch_stack callback for AMD, and drops the >> sampling-only restriction now that snapshots can be taken from software >> contexts. >> >> Leon Hwang (4): >> perf/x86/amd: Ensure amd_pmu_core_disable_all() is always inlined >> perf/x86/amd: Avoid taking branches before disabling LBR >> perf/x86/amd: Support capturing LBR from software events >> perf/x86/amd: Don't reject non-sampling events with configured LBR > > > Why is this for a stable kernel? Isn't it a new feature? If you need > this feature, why not use a newer kernel tree? > This series enables LBR snapshot support on AMD CPUs. You are right that this is not a bug fix but a feature enablement. If backporting this to the stable tree is not appropriate, that is totally fine. In that case, I will carry these changes in our in-house stable kernel instead. Thanks for the clarification. Thanks, Leon > thanks, > > greg k-h