From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D99B215D1 for ; Sun, 2 Nov 2025 06:55:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762066523; cv=none; b=uS9WoaIf0WOizNSgj2Tfh81wPFKtqWxPoD57O4F9KYKI7ffAdaAjhAcOP0wNrMvXfDklHm0D3leQAU05l0j8Z683GtYUe9cWNYErfcpQ/erYueLBjcRE06HiwBvBF51PaLkHEd6N9GD+POOY49YNXpxcMNdZLIfebfFZNqY+3hM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762066523; c=relaxed/simple; bh=tBYnTGyH9qfXFlc8Aao4j3dp21bBQ/38W4gFxr38L7c=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=BKY/FZlh2ctEV/3GUrj0rN7HYZmdSrV1MUaGpjH6JBW2pDC/J9kgQPGs761kO4sics6u0l9a40o2BK3B9Fqqd9qq8MvLLr2+gp9BLyhTkaAyhlt/IfY1IT3NeTEKPSci2bUh5fQgUQigixPkwrK/1mrn4XRRuh43gNoCyFbesQU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=svzr873t; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="svzr873t" Received: by smtp.kernel.org (Postfix) with ESMTPS id 5ADA2C4CEF7 for ; Sun, 2 Nov 2025 06:55:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762066523; bh=tBYnTGyH9qfXFlc8Aao4j3dp21bBQ/38W4gFxr38L7c=; h=From:To:Subject:Date:In-Reply-To:References:From; b=svzr873tOdvFdAgL2DMSX0Yug8I0NIYWUxAEUVU791aGOQ/ULEI8FyrAXbuBXuR1e /CtCnWY4QmzrHpmO7/O8vuShyCnYD/XvAngmFLNUB0o1UQgC+d3xppCHnp1sEKy8cm 4w40+7Bc5VwJ6fRufKojBp82e5dH0JZU8anZcpEoYva8d7w00145njowWjQ8L8wQVb p3trfOaoTWQD8JA5fSRAM+tzW4RUZ5rkmLF4EqOveWddj9yfgtKe4rNnuS8A8b2XA/ cZNLDE/3bVYAj/DZTXQtUczcPRqlutJ6nNFa15j8j1PQSxs1l3M+wp3IzjH6K4x9CG 2GRjTqfTK0Mww== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 4EFA8C41613; Sun, 2 Nov 2025 06:55:23 +0000 (UTC) From: bugzilla-daemon@kernel.org To: linux-pm@vger.kernel.org Subject: [Bug 220715] [REGRESSION] AMD P-State fails with "_CPC object is not present" on AMD Zen 4 between 6.10 and 6.11 Date: Sun, 02 Nov 2025 06:55:23 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Power Management X-Bugzilla-Component: cpufreq X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: chris.harris79@gmail.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: linux-pm@vger.kernel.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 https://bugzilla.kernel.org/show_bug.cgi?id=3D220715 --- Comment #8 from Chris Harris (chris.harris79@gmail.com) --- Thank you for the continued engagement 1) Good suggestion to test removal of 'nosmt' in the presence of 'amd_pstate=3Dpassive' on the problem kernel versions, results: In the absence of 'nosmt=3Dforce' *I am* successfully getting the "amd-psta= te" scaling driver. In the presence of 'nosmt=3Dforce' I fail to get the "amd-pstate" driver, and instead receive "acpi-cpufreq", along with the err= or "amd_pstate: the _CPC object is not present in SBIOS or ACPI disabled". Th= is behavior of 'amd_pstate=3Dpassive' failing in the presence of 'nosmt' did n= ot occur on the kernels prior to the commit identified. In my view, it does se= em to be a bug, as one should be able to achieve both 'amd_pstate=3Dpassive' a= nd 'nosmt' (as I have been on kernels prior to the affected kernels). 2) I can confirm the Ryzen 7950X is affected. I primarily tested against 4484PX on seven identical servers, all which behave similarly -- the logs shared are from one of these servers. I did a sanity-check on a single 795= 0X server, which as I said was also similarly affected, but I did not share lo= gs from that server. 3) LLM: I'll test this patch shortly. Based on the findings from question 1= ,=20 this makes perfect sense - the issue is specifically the interaction betwee= n=20 the commit and nosmt=3Dforce. Your patch changes the loop to check only ena= bled=20 CPUs rather than all present CPUs, which should skip the disabled SMT threa= ds=20 that don't have CPC structures initialized. I'll apply this to a current kernel (6.11+) and test with both: - amd_pstate=3Dpassive + nosmt=3Dforce (currently broken) - amd_pstate=3Dpassive without nosmt (currently works) Will report back with results tomorrow. --=20 You may reply to this email to add a comment. You are receiving this mail because: You are the assignee for the bug.=