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 997B239EB59 for ; Thu, 24 Sep 2026 01:45:50 +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=1790214353; cv=none; b=KSRDQj3MU5TpZCP5E4FJXCsGiObi2J8Nt46bJ6S5/u07blGji467KfIj79QqYb+qkr1kUJP96RmoA8eFl0xysoQqvy9cixaoaAWhzhkdsuPD4TIin+jbg9Z3OkL1yqKnpHcTO9jzS7RKSY9dkLJXyo99ujFX7WeKG0OhRAJwfsE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790214353; c=relaxed/simple; bh=aRRi6RHOjTOyCJ/5HtsiLAqhCPs9CduVQPKUndFydks=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=M1wRhJEEUQ2RoEEYTdoFGSVyrcFpL5OMTICGI9rpj6l4teCQ+rXQUN3tiG0OZstwMpcFLH6a66lyMybth+AEFg0lKDP9jPFgI0KNvIqA6Su9/5+nOb/aoG8rtE5uOSElblmlPFp2efR1HA8MRwhz1TjcNlGYflmG9j+91CafcAE= 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=fail (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=dLh1rHhN reason="signature verification failed"; 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=fail reason="signature verification failed" (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="dLh1rHhN" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 06C9340E015D; Thu, 24 Sep 2026 01:45:48 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=fail (4096-bit key) reason="fail (body has been altered)" 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 TvbiNa2KeqAs; Thu, 24 Sep 2026 01:45:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1790214337; bh=K4Rjc0zg3eS2N5HthlBowVt5KP/fUl4gPGDlXBupBBw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dLh1rHhN3tOa99B2mh2ge76ptxzketW9gjSmLr8l4gv4G7u3hfzhmwMEK/7qkYe+D yu3rUcu0HlmHG77mGrKWBMkhL6weYHntcHxtDbubnh7tGy/dKxh5qHeSzcCQo84Whh Woj8NuO+PEQCztKPWVtV6gjy5Dy0nOK0KNEmCdkDQpqDvCcOTXJVPg+/hr/8C5CKRR hcstMLw9/3BbWys5JTg55jVQnd2BcNhMgThsKXInjGprHCOTxBzLIOMJ8aFJ1LgRp3 REQZ6FCSo8hqKy6ZbJF7xnUKp2vprPm23KCE8uo915nI4GNhCMXk7Liy1W6Hloni/D kSLWxEcTP6zyKg9KzbM9Ra/8dv/dmUsDKB+z4eowVONp8ATdVuP4vsMkjDlwDGmieW XkYc//1wAKjfMfdr42s+rRCme6T8/qI56Knz/+iy2s7y5B212R52IPYjviEjVK+LeO Hjru5IfRfhPXrx0VMTT06X0kIXNqAamSCKyhyZzWb+YZ8KMmJltuQf+d84rIM1MUwq ARqkW6uXnxiYyl9EWpIyfSy2qMxkbaB0dHFpVswcZlCRKiZKAcuJEOYuqoLda7NBfI wucrymXTfFqXfvE2clGg5agfBWVeTRre8xW9f5YQF+KhlSJLBhk1MyVfGyX2ZEfJCr QCwzwfsHbb5e6dOG3OHtvnoM= Received: from stx.tnic (unknown [IPv6:2600:1700:38ca:c00::48]) (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 3BB7540E00B8; Thu, 24 Sep 2026 01:45:21 +0000 (UTC) Date: Wed, 23 Sep 2026 18:45:17 -0700 From: Borislav Petkov To: Kim Phillips Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, Sean Christopherson , Paolo Bonzini , K Prateek Nayak , Nikunj A Dadhania , Tom Lendacky , Michael Roth , Naveen Rao , David Kaplan , Pawan Gupta , Dave Hansen , Nathan Fontenot Subject: Re: [PATCH v5 1/8] x86/bugs: Allow forcing Automatic IBRS with SNP active using spectre_v2=eibrs Message-ID: <20260924014517.GEarSArVM12m_ZshhA@fat_crate.local> References: <20260826223510.3669875-1-kim.phillips@amd.com> <20260826223510.3669875-2-kim.phillips@amd.com> <20260903040330.GNapjxkgMd2Ey38egR@fat_crate.local> <01b57e61-df45-44a6-848b-c19eae226ad0@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <01b57e61-df45-44a6-848b-c19eae226ad0@amd.com> Content-Transfer-Encoding: quoted-printable On Fri, Sep 18, 2026 at 06:00:21PM -0500, Kim Phillips wrote: > That fallback cannot be overridden.=C2=A0 An admin running an SNP host = whose > workload is dominated by guest activity rather than host userspace may > well prefer AutoIBRS Why would she/he prefer to do that? Any persuasive arguments to make her/= him do that? --=20 Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette