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 E534B2DBBAD; Mon, 14 Apr 2025 13:31:49 +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=1744637510; cv=none; b=hXNA5TCVZqh1PJOG28WW7AXNPln6Cbz590rFQ/FazYsshQMJgiLix3kXQ/zbbPkvxVxm3BPHtIscIS930ynynsOxnyJjUYrkYbmhprwXJD9NslwNp4d5AEa35BfsNM/y3E5xgzfLowpSyZrU0B21tSRlVDPIiHg6MbTfJ099Z0I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744637510; c=relaxed/simple; bh=ABGrbOOCHy9TvIkq7lavDKL7D/kyz6ySl69itUYd3lQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=hQWRQZBmE5cBhRBWeTeUbbPX57U2naQFUItGwxIrgh7gccnFca8vOS1hcQXZ2sbo8a/z7o//KGTAL48rr2jVa8toQZ1agwAdI/G1cdm7OS8hVTRjH9Dhey3DzM23371ymKF87BgXW1wthlK/WbvVc79lcAhEogrHPBYYaIYsEMk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KDyLqQ6n; 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="KDyLqQ6n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79B38C4CEE2; Mon, 14 Apr 2025 13:31:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744637509; bh=ABGrbOOCHy9TvIkq7lavDKL7D/kyz6ySl69itUYd3lQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KDyLqQ6ngJAMQp1BZfAyP9jNBOUFmOs/JDjwHNo0ho2Qk9cLmGXu17lkPyOntl6Cd feDAP9ztcWHA6goOZWgZrxFwDRery+Qgq9G4nkj7hGCtFVeUZPCS6sHHRI7rQpM9h0 5wgQHIAkxcC4RTKSRJm+3uSptCRjQr+evm153DGWjuItZsK0iiPxo3yhM+tyIqWNVf LI4lO0lUZW7ijxutQo8TZN10w2emHtjof8yQvBWCrX2fmaGTLfbylrQHo+REHDMhOX IBiDqYGa0+GzU2TKvKYoTIkEKfHG4HMvqXIyoDAnudxGjNzZ74VCkVviTvq4ZIkqKd F6EVIfnC2SI8Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Josh Poimboeuf , Pawan Gupta , Ingo Molnar , Amit Shah , Nikolay Borisov , Paolo Bonzini , Vitaly Kuznetsov , Sean Christopherson , David Woodhouse , Sasha Levin , tglx@linutronix.de, bp@alien8.de, peterz@infradead.org, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org Subject: [PATCH AUTOSEL 5.15 11/15] x86/bugs: Don't fill RSB on VMEXIT with eIBRS+retpoline Date: Mon, 14 Apr 2025 09:31:21 -0400 Message-Id: <20250414133126.680846-11-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250414133126.680846-1-sashal@kernel.org> References: <20250414133126.680846-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.180 Content-Transfer-Encoding: 8bit From: Josh Poimboeuf [ Upstream commit 18bae0dfec15b24ec14ca17dc18603372f5f254f ] eIBRS protects against guest->host RSB underflow/poisoning attacks. Adding retpoline to the mix doesn't change that. Retpoline has a balanced CALL/RET anyway. So the current full RSB filling on VMEXIT with eIBRS+retpoline is overkill. Disable it or do the VMEXIT_LITE mitigation if needed. Suggested-by: Pawan Gupta Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Reviewed-by: Pawan Gupta Reviewed-by: Amit Shah Reviewed-by: Nikolay Borisov Cc: Paolo Bonzini Cc: Vitaly Kuznetsov Cc: Sean Christopherson Cc: David Woodhouse Link: https://lore.kernel.org/r/84a1226e5c9e2698eae1b5ade861f1b8bf3677dc.1744148254.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin --- arch/x86/kernel/cpu/bugs.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index dfc02fb32375c..018ef230f02ce 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1579,20 +1579,20 @@ static void __init spectre_v2_determine_rsb_fill_type_at_vmexit(enum spectre_v2_ case SPECTRE_V2_NONE: return; - case SPECTRE_V2_EIBRS_LFENCE: case SPECTRE_V2_EIBRS: + case SPECTRE_V2_EIBRS_LFENCE: + case SPECTRE_V2_EIBRS_RETPOLINE: if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) { - setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT_LITE); pr_info("Spectre v2 / PBRSB-eIBRS: Retire a single CALL on VMEXIT\n"); + setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT_LITE); } return; - case SPECTRE_V2_EIBRS_RETPOLINE: case SPECTRE_V2_RETPOLINE: case SPECTRE_V2_LFENCE: case SPECTRE_V2_IBRS: - setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT); pr_info("Spectre v2 / SpectreRSB : Filling RSB on VMEXIT\n"); + setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT); return; } -- 2.39.5