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Wed, 20 Nov 2019 09:40:07 -0800 (PST) Subject: Re: [PATCH for-4.2 1/2] i386: Add new versions of Skylake/Cascadelake/Icelake without TSX To: Eduardo Habkost , qemu-devel@nongnu.org References: <20191120164912.32384-1-ehabkost@redhat.com> <20191120164912.32384-2-ehabkost@redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Wed, 20 Nov 2019 18:40:06 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191120164912.32384-2-ehabkost@redhat.com> Content-Language: en-US X-MC-Unique: tWlVGYvsMm27uXgk3O8G2g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: Jiri Denemark , Kashyap Chamarthy , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 20/11/19 17:49, Eduardo Habkost wrote: > One of the mitigation methods for TAA[1] is to disable TSX > support on the host system. Linux added a mechanism to disable > TSX globally through the kernel command line, and many Linux > distributions now default to tsx=3Doff. This makes existing CPU > models that have HLE and RTM enabled not usable anymore. >=20 > Add new versions of all CPU models that have the HLE and RTM > features enabled, that can be used when TSX is disabled in the > host system. What is the effect of this when using "-cpu CascadeLake-Server" and upgrading QEMU? Would it automatically switch to the new version? If so, would it be better to include a duplicate of the models (and if so, that would conflict with my VMX features patch, which is also for 4.2). Paolo