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 1EAD8C433F5 for ; Wed, 16 Mar 2022 17:52:51 +0000 (UTC) Received: from localhost ([::1]:33718 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nUXpJ-0002AW-Uo for qemu-devel@archiver.kernel.org; Wed, 16 Mar 2022 13:52:50 -0400 Received: from eggs.gnu.org ([209.51.188.92]:55198) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nUXnj-00011A-8h for qemu-devel@nongnu.org; Wed, 16 Mar 2022 13:51:13 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:23928) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nUXnf-000844-CP for qemu-devel@nongnu.org; Wed, 16 Mar 2022 13:51:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647453066; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TdRLl7jRzmLItVI9/Mwhd0xPliK3Eg/Xpmi8xtiF3N8=; b=dm8rpolQ/3p6pLuO3tPGVkfw6o7l7y2FapgLB2lphSoo4zzM5d+TBAzhFSaCr6jhiDhtgJ PvSk2qVIL6XixlQ8G8iV+uKbstwrR9tjA0js/7RHXwwyIDK+VUdxNLo824OosGlWmeZLfQ 1p0ue02tkMTsW49x6JW7x+yCOAa5Ps4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-166-bnUPLBZmNsOtFZaMUzNIUg-1; Wed, 16 Mar 2022 13:50:53 -0400 X-MC-Unique: bnUPLBZmNsOtFZaMUzNIUg-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 383DE1066558; Wed, 16 Mar 2022 17:50:53 +0000 (UTC) Received: from redhat.com (unknown [10.39.195.81]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CDFAE432485; Wed, 16 Mar 2022 17:50:51 +0000 (UTC) Date: Wed, 16 Mar 2022 17:50:49 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: David Edmondson Subject: Re: [PULL 15/22] x86: Grant AMX permission for guest Message-ID: References: <20220308113445.859669-1-pbonzini@redhat.com> <20220308113445.859669-16-pbonzini@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit 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: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, 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_H5=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?= Cc: Yang Zhong , Paolo Bonzini , Peter Krempa , qemu-devel@nongnu.org, Jing Liu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Mar 16, 2022 at 05:48:04PM +0000, David Edmondson wrote: > On Wednesday, 2022-03-16 at 16:05:01 GMT, Daniel P. Berrangé wrote: > > > On Wed, Mar 16, 2022 at 04:57:39PM +0100, Peter Krempa wrote: > >> On Tue, Mar 08, 2022 at 12:34:38 +0100, Paolo Bonzini wrote: > >> > From: Yang Zhong > >> > > >> > Kernel allocates 4K xstate buffer by default. For XSAVE features > >> > which require large state component (e.g. AMX), Linux kernel > >> > dynamically expands the xstate buffer only after the process has > >> > acquired the necessary permissions. Those are called dynamically- > >> > enabled XSAVE features (or dynamic xfeatures). > >> > > >> > There are separate permissions for native tasks and guests. > >> > > >> > Qemu should request the guest permissions for dynamic xfeatures > >> > which will be exposed to the guest. This only needs to be done > >> > once before the first vcpu is created. > >> > > >> > KVM implemented one new ARCH_GET_XCOMP_SUPP system attribute API to > >> > get host side supported_xcr0 and Qemu can decide if it can request > >> > dynamically enabled XSAVE features permission. > >> > https://lore.kernel.org/all/20220126152210.3044876-1-pbonzini@redhat.com/ > >> > > >> > Suggested-by: Paolo Bonzini > >> > Signed-off-by: Yang Zhong > >> > Signed-off-by: Jing Liu > >> > Message-Id: <20220217060434.52460-4-yang.zhong@intel.com> > >> > Signed-off-by: Paolo Bonzini > >> > --- > >> > target/i386/cpu.c | 7 +++++ > >> > target/i386/cpu.h | 4 +++ > >> > target/i386/kvm/kvm-cpu.c | 12 ++++---- > >> > target/i386/kvm/kvm.c | 57 ++++++++++++++++++++++++++++++++++++++ > >> > target/i386/kvm/kvm_i386.h | 1 + > >> > 5 files changed, 75 insertions(+), 6 deletions(-) > >> > >> With this commit qemu crashes for me when invoking the following > >> QMP command: > > > > It is way worse than that even. If you remove '-S' you get an > > immediate kaboom on startup on AMD hosts > > Which AMD CPU is in this host? AMD EPYC 7302P 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 :|