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 052CD21772B; Tue, 29 Apr 2025 16:53:39 +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=1745945620; cv=none; b=HrdRpmT98A3So5gNLJzZJdAixVPoh5/NNCyspQsUWGG3oyIOOu0mDNbfmRAUMp6Gsvbl70GbT6jeSEdRkx46UvCkKM+rhZZTdFCOcHmUZd2ce/AfXgyj+wEaDBDobruHmz6VU9Zy/vpBoebyWuQWrfuPVqlxZ7vJCNNSGnUSx5A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745945620; c=relaxed/simple; bh=inuRLI9xkoKFOKHm2I76b56dKxL8l/BiZL59RStelFY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u8wx5n1CcT/lxx2MESz+UdA4aqzVP+rFYyf9dW8Z8SPnHN3QOibhze7ud8kCwqMISBrJr9k/nCH/WN1FpoR6EbhcrzeGN43xySedRNQ1tedPZRUVUO0Miwo2HAMAP+TRbZVpk/J18x8LVtnEgNBe1AwU4VLIvnm1dEg+n7tGM7M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SabriPpn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="SabriPpn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1835FC4CEE3; Tue, 29 Apr 2025 16:53:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1745945619; bh=inuRLI9xkoKFOKHm2I76b56dKxL8l/BiZL59RStelFY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SabriPpnZRxtxF0rOvWzk8zt8LgttoyOqFzT9cYPOADj2qdfdZWOX25v0eQ6+mOe1 0uWK9FUsqC6zgf6n/9AbwYjljoj3l9fNX8CSiE3gek2a8YY4G3UNO7ldgpkRE/OWql Df4Y2EiNCrvwfDLOrQ5f090Mt9EzD2sldaMeTmUQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pawan Gupta , Josh Poimboeuf , Ingo Molnar , Amit Shah , Nikolay Borisov , Paolo Bonzini , Vitaly Kuznetsov , Sean Christopherson , David Woodhouse , Sasha Levin Subject: [PATCH 5.4 173/179] x86/bugs: Dont fill RSB on VMEXIT with eIBRS+retpoline Date: Tue, 29 Apr 2025 18:41:54 +0200 Message-ID: <20250429161056.394306314@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250429161049.383278312@linuxfoundation.org> References: <20250429161049.383278312@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ 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 af748d1c78d41..4f803aed2ef0e 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1348,20 +1348,20 @@ 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