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 86F45295502 for ; Wed, 14 May 2025 20:13:40 +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=1747253621; cv=none; b=kO+wKC2T9HXPvXCy29JFap6ZGGXTIbMTuNUyNeGQkjO3stu8ih9sfCdyM3JMC66dm24GLIBruIt/l53JHp2rALnEu4QMc91n1CXJzuiu9tYlLwmIVtgMADZBZXLYNfP8r5wiFd6pqMm052qLn6x9jOZnmGNEZp40BkkRUf7ufNc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747253621; c=relaxed/simple; bh=AEl70ACJzLqV82ZPjpUpFuGVrV8h39v5aAPB8niW+Lc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=ufrEkO03mJcOvrCSsTb0bz8AWs9T4BQDMS28V1a3o5h/KQGTZW9oer8PHVPJMXWoSAIL2inopBsw9ufW9ZDgISStvUGiTrKv6QaAUyMLqAjKojdl94VKZycaQTb3uW0BlFn7dshPDP9iEMoFQ96UpMXqWygL1H1KqmlsKdbKT1w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uVJJPBq6; 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="uVJJPBq6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FBDBC4CEE3; Wed, 14 May 2025 20:13:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747253620; bh=AEl70ACJzLqV82ZPjpUpFuGVrV8h39v5aAPB8niW+Lc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uVJJPBq6tcr0/dFw7bf/K9gdjylqg1xd5Z4z6hUDtAd9ipjdf0FmZduV90nPflAQp bwX6ZE1bDbs7Q9/l2AGJhlrIpSQoBRCaA9IAxIcWSjcCnWd/DXvKaL/wguw0GZB/Jp 53NRI8SQTmFNEXUnvN3b+gAlxEkJJNzjZCINOog3JLa3qYt8+XQls1TH1b3uOrnXL3 /0X4Bn4IqJCV30arRgrjWaBypTA6LBA9wxPlhISIoZUxkfmMa+2kAgX5DpVdTfemKP B35lWZtgWzc7MtNZGWiCR8hAjwKEJLpJiukBZdbVLIZd9J6KUBzuMhmR4QXyw15npq 22KiSRB0HtLig== From: Sasha Levin To: stable@vger.kernel.org Cc: Pawan Gupta , Sasha Levin Subject: Re: [PATCH 5.15 v2 13/14] x86/its: Align RETs in BHB clear sequence to avoid thunking Date: Wed, 14 May 2025 16:13:37 -0400 Message-Id: <20250514113946-23aea5f5b7d675ec@stable.kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250513-its-5-15-v2-13-90690efdc7e0@linux.intel.com> References: Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Sasha's backport helper bot ] Hi, ✅ All tests passed successfully. No issues detected. No action required from the submitter. The upstream commit SHA1 provided is correct: f0cd7091cc5a032c8870b4285305d9172569d126 Status in newer kernel trees: 6.14.y | Present (different SHA1: 375fe8890b23) 6.12.y | Present (different SHA1: 5eaa60e1baf1) 6.6.y | Present (different SHA1: f17249f8a872) 6.1.y | Present (different SHA1: 724e897203bd) Note: The patch differs from the upstream commit: --- 1: f0cd7091cc5a0 ! 1: 9b2b6206dceda x86/its: Align RETs in BHB clear sequence to avoid thunking @@ Metadata ## Commit message ## x86/its: Align RETs in BHB clear sequence to avoid thunking + commit f0cd7091cc5a032c8870b4285305d9172569d126 upstream. + The software mitigation for BHI is to execute BHB clear sequence at syscall entry, and possibly after a cBPF program. ITS mitigation thunks RETs in the lower half of the cacheline. This causes the RETs in the BHB clear sequence @@ arch/x86/entry/entry_64.S: SYM_CODE_END(rewind_stack_and_make_dead) + * Target Selection, rather than taking the slowpath via its_return_thunk. */ SYM_FUNC_START(clear_bhb_loop) - ANNOTATE_NOENDBR + push %rbp @@ arch/x86/entry/entry_64.S: SYM_FUNC_START(clear_bhb_loop) call 1f jmp 5f --- Results of testing on various branches: | Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-6.1.y | Success | Success |