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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48132 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kKP4x-0006Vz-4x for qemu-devel@archiver.kernel.org; Mon, 21 Sep 2020 12:54:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34172) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kKP1Q-0004id-26 for qemu-devel@nongnu.org; Mon, 21 Sep 2020 12:50:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:22040) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kKP1N-0002N5-Va for qemu-devel@nongnu.org; Mon, 21 Sep 2020 12:50:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600707033; h=from:from: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; 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auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ehabkost@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/21 01:43:11 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.455, 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 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Strong, Beeman" , "qemu-devel@nongnu.org" , Robert Hoo , "pbonzini@redhat.com" , Jiri Denemark , "rth@twiddle.net" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Sep 21, 2020 at 07:49:22AM +0000, Kang, Luwei wrote: > Hi Eduardo, > This patch set will remove some limitations of Intel PT CPUID information. > 1. The "IP payloads" feature will disable the Intel PT in guests and it will be coming soon. > 2. To make the live migration safe, we set the Intel PT CPUID as a constant value(Icelake server CPUID). It will mask off the new feature of Intel PT. Isn't this series doing the opposite of 2? It replaces all constant CPUID values with kvm_arch_get_supported_cpuid(), making the feature unavailable in migration-safe mode. Does it mean the plan is to drop intel-pt migration support entirely? > > About this issue https://bugzilla.redhat.com/show_bug.cgi?id=1853972, Intel PT is disabled in the guest by default, we should use "-cpu Icelake-Server,+intel-pt" to enable the Intel PT. That's correct. The point of the BZ is that libvirt mode=host-model was expected to include intel-pt automatically when available. With this series, the request in the BZ stops making sense (because intel-pt won't be migration-safe anymore), but I'm not sure yet that's really the plan. > > Thanks, > Luwei Kang > > > -----Original Message----- > > From: Eduardo Habkost > > Sent: Saturday, September 19, 2020 6:03 AM > > To: Kang, Luwei > > Cc: pbonzini@redhat.com; rth@twiddle.net; qemu-devel@nongnu.org; Strong, > > Beeman ; Jiri Denemark > > ; Robert Hoo > > Subject: Re: [PATCH v1 0/3] Remove the limitation of Intel PT CPUID info > > > > Hi Luwei Kang, > > > > I was looking for info on intel-pt and just saw this series, and it was never > > reviewed or merged (sorry for missing it!). Is this still the approach we want to > > follow for intel-pt? > > > > I'm CCing Jiri Denemark because this might be relevant for a libvirt issue related > > to intel-pt we were investigating[1]. > > > > [1] https://bugzilla.redhat.com/show_bug.cgi?id=1853972 > > > > > > On Mon, Mar 30, 2020 at 09:56:09AM +0000, Kang, Luwei wrote: > > > > -----Original Message----- > > > > From: Kang, Luwei > > > > Sent: Tuesday, February 25, 2020 5:38 AM > > > > To: pbonzini@redhat.com; rth@twiddle.net; ehabkost@redhat.com > > > > Cc: qemu-devel@nongnu.org; Strong, Beeman > > ; > > > > Kang, Luwei > > > > Subject: [PATCH v1 0/3] Remove the limitation of Intel PT CPUID info > > > > > > > > The Intel PT feature includes some > > > > sub-features(CPUID.(EAX=14H,ECX=0H)) > > > > and these sub-features are different on different HW platforms. To > > > > make the live migration safety(get the same CPUID info with same cpu > > > > model on different HW platform), the current Intel PT CPUID > > > > information is set to a constant value(from ICELAKE Server). > > > > > > > > It will block the new feature in the later HW platform. what's more, > > > > the support of "IP payloads" will disable the Intel PT in KVM > > > > guest(patch 1) but it will come soon. > > > > > > > > This patchset remove this limitation and expose all the capabilities > > > > to KVM guest. As it will break the live migration safe, Intel PT > > > > will be masked as unmigratable. > > > > > > Ping. > > > > > > Thanks, > > > Luwei Kang > > > > > > > > > > > Luwei Kang (3): > > > > i386: Remove the limitation of IP payloads for Intel PT > > > > i386: Remove the CPUID limitation of Intel PT > > > > i386: Mark the 'INTEL_PT' CPUID bit as unmigratable > > > > > > > > target/i386/cpu.c | 69 > > > > ++++--------------------------------------------------- > > > > 1 file changed, 5 insertions(+), 64 deletions(-) > > > > > > > > -- > > > > 1.8.3.1 > > > > > > > -- > > Eduardo > -- Eduardo