From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 48C7CCD11DC for ; Wed, 20 Mar 2024 12:33:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rmv8J-0005Dz-ED; Wed, 20 Mar 2024 08:33:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmv8I-00058Q-1Z for qemu-devel@nongnu.org; Wed, 20 Mar 2024 08:33:26 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmv8F-0005Nf-Kf for qemu-devel@nongnu.org; Wed, 20 Mar 2024 08:33:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1710938003; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=LI54pxdGKEWVTWxWzs7S5KmA8mpkqqZDrOFVx2kvCH0=; b=egAZAaNh5rZHFPSns2pKudBzvKyzU66QSJmp4Z0TklCXn2Z9FtHF2NO2O/IY/Vgvco9JaV T9S96NpqZaZwyIPrnxQVJt+pNrCwcIKfStMWJNoM3gky8wie/y1ktAcYD4O/VB0Lfo5QyA EK3STXXoz/r/pntM0+v50oJARghgmFc= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-220-URfAf05JNkG4lG_Pftr4Uw-1; Wed, 20 Mar 2024 08:33:17 -0400 X-MC-Unique: URfAf05JNkG4lG_Pftr4Uw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2EE8F1C54460; Wed, 20 Mar 2024 12:33:17 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.205]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 10A69112132A; Wed, 20 Mar 2024 12:33:15 +0000 (UTC) Date: Wed, 20 Mar 2024 12:33:10 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Michael Roth Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Tom Lendacky , Paolo Bonzini , Markus Armbruster , Pankaj Gupta , Xiaoyao Li , Isaku Yamahata Subject: Re: [PATCH v3 29/49] i386/sev: Don't disable block discarding for SNP Message-ID: References: <20240320083945.991426-1-michael.roth@amd.com> <20240320083945.991426-30-michael.roth@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240320083945.991426-30-michael.roth@amd.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.417, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Mar 20, 2024 at 03:39:25AM -0500, Michael Roth wrote: > SEV/SEV-ES rely on pinned memory to back guest RAM so discarding > isn't actually possible. With SNP, only guest_memfd pages are used > for private guest memory, so discarding of shared memory is still > possible, so only disable discard for SEV/SEV-ES. > > Signed-off-by: Michael Roth > --- > target/i386/sev.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/target/i386/sev.c b/target/i386/sev.c > index 134e8f7c22..43e6c0172f 100644 > --- a/target/i386/sev.c > +++ b/target/i386/sev.c > @@ -888,10 +888,18 @@ static int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp) > uint32_t host_cbitpos; > struct sev_user_data_status status = {}; > > - ret = ram_block_discard_disable(true); > - if (ret) { > - error_report("%s: cannot disable RAM discard", __func__); > - return -1; > + /* > + * SEV/SEV-ES rely on pinned memory to back guest RAM so discarding > + * isn't actually possible. With SNP, only guest_memfd pages are used > + * for private guest memory, so discarding of shared memory is still > + * possible.. > + */ > + if (!sev_snp_enabled()) { > + ret = ram_block_discard_disable(true); > + if (ret) { > + error_report("%s: cannot disable RAM discard", __func__); > + return -1; > + } > } Pre-existing code bug, but this method must use 'error_setg' to fill the 'Error **errp' parameter. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|