From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (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 3CDC722611; Wed, 8 Jan 2025 19:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736365544; cv=none; b=cOOIng/jLs1PCUxJFVdoGiCojkrLXzfdBCled5iO0gTlCV7kVc1TbbZLCzhRViRIK8/Si5BkcU4n7Eb7rZurUxxnBi1Mjk+e0t5um/76MUJU3z58/zG8ynqnnceSdHKqPHJla/VCgC/BRFly7E4DAqrcMd3GAhw5SzN+iiTcZmY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736365544; c=relaxed/simple; bh=ESNIhBVidArw1PzHx6nFQNXSzGZ8ukWaPMDbnFED78U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=crGOW3JJpTOw1TFEIlyphHJ/6sDqN9A5Llr1fEudFuV2tUDAzcQ9TcLcXzs/HtHAOz3P1Nk+j84RVq6zF0F3z9HTAYzxo493ScDPSCKksZZgLNWs66oQUZ8LwRS+6XgGwWuQAbV5faVgcRCtTlDFH9zHEjseLahPiAfZYwYweMM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=IPDldci8; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="IPDldci8" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 073C640E0289; Wed, 8 Jan 2025 19:45:40 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=pass (4096-bit key) header.d=alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 7-Febcck8mql; Wed, 8 Jan 2025 19:45:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1736365535; bh=x610/Zndo4IGnCTdF90flcGR1Vy2KvG9JPGuM4xgiXg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IPDldci8dIqF0HYhoyvz6nR1FRz/rWBfNYMNGr/Gl0nlQkGqmcvIf9XQrj4A+tkYC vkDj2WjbdHyLCQbf3weOZDAqJAWd4hu75dPYVopmN6BsfmStlfBhsdR7nHhqQBWdFD L31sMhOtQweEFctcY2kEBkmYKuaUupOsiMRCmG2XND0kVJPXiHrkk3YAUgWlwyD4wp hzYcasM+E4rOG0EPKTJbBPLbbkOf79wFwrWS8TxYnDKuSlGs9WCZx+2H3koe4WihzI uza6ZhA3daCrRbNrpcWghut4ggmCn/FsEQJjGl+yTJl6ULKGX3+zML6DD2UyUFRPLU TRUjV+qCxMAsmQBlSGfrS+cP/+1XnIvCVQD0pnRZf1tMi65FPACdfA6WCyn4Xz5yb6 EgiockRI9S2LC3W5a7/js6Yg+WXbLg1pnv6BUxJKDTxAFgQGkSbm1zvToMx7plY47R tuut/ryS4224LJEkyrBMPPxsOqU3226wq9c1I5yVXjfCBOcq10oa3b3Rpd42WZibeG swBfI7sJtLNGFE7Tqhl9JXRFInGiS+qYX9nCtCNtnLF+PCRy70/S+CFoDoeB5xypF2 i6jppCjN5qGRw5/gzBZGmDyjMUWFxR9PkSCMasTzSX8fDgC/qJXeEYeJja7KdDz/h0 QiQrmVjVOWs8Iktb6uz9OQqQ= Received: from zn.tnic (p200300eA971f938F329C23FffEa6A903.dip0.t-ipconnect.de [IPv6:2003:ea:971f:938f:329c:23ff:fea6:a903]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 7605E40E01F9; Wed, 8 Jan 2025 19:45:26 +0000 (UTC) Date: Wed, 8 Jan 2025 20:45:20 +0100 From: Borislav Petkov To: Jim Mattson Cc: Sean Christopherson , Borislav Petkov , X86 ML , Paolo Bonzini , Josh Poimboeuf , Pawan Gupta , KVM , LKML Subject: Re: [PATCH v2 3/4] x86/bugs: KVM: Add support for SRSO_MSR_FIX Message-ID: <20250108194520.GIZ37V0OVGLtRAWSF_@fat_crate.local> References: <20241216173142.GDZ2Bj_uPBG3TTPYd_@fat_crate.local> <20241230111456.GBZ3KAsLTrVs77UmxL@fat_crate.local> <20250108154901.GFZ36ebXAZMFZJ7D8t@fat_crate.local> <20250108181434.GGZ37AiioQkcYbqugO@fat_crate.local> <20250108191447.GHZ37Op2mdA5Zu6aKM@fat_crate.local> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Wed, Jan 08, 2025 at 11:43:14AM -0800, Jim Mattson wrote: > > We don't need safe-RET with SRSO_USER_KERNEL_NO=1. And there's no safe-RET for > > virt only. So IBPB-on-VMEXIT is the next best thing. The good thing is, those > > machines have BpSpecReduce too so you won't be doing IBPB-on-VMEXIT either but > > what we're talking about here - BpSpecReduce. > > I'm suggesting that IBPB-on-VMexit is probably the *worst* thing. I know what you're suggesting and I don't think so but I'd need to look at the numbers. > If it weren't for BpSpecReduce, I would want safe-RET for virt only. Read my reply again. > (Well, if it weren't for ASI, I would want that, anyway.) I'm sure Brendan is waiting for reviews there. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette