From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH 1/2] i386: define the AMD 'amd-ssbd' CPUID feature bit Date: Mon, 4 Jun 2018 16:20:53 -0400 Message-ID: <20180604202053.GG5867@char.us.oracle.com> References: <20180601145921.9500-1-konrad.wilk@oracle.com> <20180601153809.15259-1-konrad.wilk@oracle.com> <20180601153809.15259-2-konrad.wilk@oracle.com> <20180604085440.GB19749@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Cc: pbonzini@redhat.com, ehabkost@redhat.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, rth@twiddle.net To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Return-path: Content-Disposition: inline In-Reply-To: <20180604085440.GB19749@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel2=m.gmane.org@nongnu.org Sender: "Qemu-devel" List-Id: kvm.vger.kernel.org On Mon, Jun 04, 2018 at 09:54:40AM +0100, Daniel P. Berrang=E9 wrote: > On Fri, Jun 01, 2018 at 11:38:08AM -0400, Konrad Rzeszutek Wilk wrote: > > AMD future CPUs expose _two_ ways to utilize the Intel equivalant > > of the Speculative Store Bypass Disable. The first is via > > the virtualized VIRT_SPEC CTRL MSR (0xC001_011f) and the second > > is via the SPEC_CTRL MSR (0x48). The document titled: > > 124441_AMD64_SpeculativeStoreBypassDisable_Whitepaper_final.pdf > >=20 > > gives priority of SPEC CTRL MSR over the VIRT SPEC CTRL MSR. > >=20 > > A copy of this document is available at > > https://bugzilla.kernel.org/show_bug.cgi?id=3D199889 > >=20 > > Anyhow, this means that on future AMD CPUs there will be _two_ ways = to > > deal with SSBD. >=20 > Oh what fun ;-) >=20 > Unless I'm mistaken the current Linux kernel doesn't know about these > new amd-ssbd / amd-no-ssb flags either. Will you also be sending patche= s > for that half of the problem ? I sent them as well. But forgot to CC qemu-devel :-(