From mboxrd@z Thu Jan 1 00:00:00 1970 From: Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH v5 untested] kvm: better MWAIT emulation for guests Date: Tue, 4 Apr 2017 15:44:46 +0200 Message-ID: <20170404134445.GB9525@potion> References: <1489612895-12799-1-git-send-email-mst@redhat.com> <87f187de-64ef-22a2-7714-a811883bce02@suse.de> <20170328142837.GA21738@potion> <20170329121147.GA5129@potion> <20170404123915.GA9525@potion> <20170404131308.GA9826@potion> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: Jim Mattson , "Michael S. Tsirkin" , LKML , "Gabriel L. Somlo" , Paolo Bonzini , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , the arch/x86 maintainers , Joerg Roedel , kvm list , linux-doc@vger.kernel.org, qemu-devel@nongnu.org To: Alexander Graf Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org [Cc qemu-devel as we've gone off-topic] 2017-04-04 15:15+0200, Alexander Graf: > On 04/04/2017 03:13 PM, Radim Krčmář wrote: >> 2017-04-04 14:51+0200, Alexander Graf: >> > Please see my patch to force enable CPUID bits ;). >> Nice. MWAIT could also use setting of arbitrary values for its leaf, >> but a generic interface for that would probably look clunky on the >> command line ... > > > I think we should have an interface similar to smbios for that eventually. > Something where you can explicitly set arbitrary CPUID leaf information > using leaf specific syntax. There are more leafs where it would make sense - > cache topology for example. Right, separating cpuid from -cpu makes it bearable, like -cpuid leaf=%x[,subleaf=%x][,eax=%x][,ebx=%x][,ecx=%x][,edx=%x] And Having multiple interfaces for the same thing would result in some corner case decisions ... I think QEMU should check that feature flags specified flags specified by -cpu are not cleared by -cpuid. I'm not sure if setters like "|=" and "&=~" would be beneficial in some cases. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33404) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cvOlW-0003M7-PC for qemu-devel@nongnu.org; Tue, 04 Apr 2017 09:44:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cvOlT-00087v-Lh for qemu-devel@nongnu.org; Tue, 04 Apr 2017 09:44:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54922) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cvOlT-00087V-FG for qemu-devel@nongnu.org; Tue, 04 Apr 2017 09:44:55 -0400 Date: Tue, 4 Apr 2017 15:44:46 +0200 From: Radim =?utf-8?B?S3LEjW3DocWZ?= Message-ID: <20170404134445.GB9525@potion> References: <1489612895-12799-1-git-send-email-mst@redhat.com> <87f187de-64ef-22a2-7714-a811883bce02@suse.de> <20170328142837.GA21738@potion> <20170329121147.GA5129@potion> <20170404123915.GA9525@potion> <20170404131308.GA9826@potion> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v5 untested] kvm: better MWAIT emulation for guests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: Jim Mattson , "Michael S. Tsirkin" , LKML , "Gabriel L. Somlo" , Paolo Bonzini , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , the arch/x86 maintainers , Joerg Roedel , kvm list , linux-doc@vger.kernel.org, qemu-devel@nongnu.org [Cc qemu-devel as we've gone off-topic] 2017-04-04 15:15+0200, Alexander Graf: > On 04/04/2017 03:13 PM, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote: >> 2017-04-04 14:51+0200, Alexander Graf: >> > Please see my patch to force enable CPUID bits ;). >> Nice. MWAIT could also use setting of arbitrary values for its leaf, >> but a generic interface for that would probably look clunky on the >> command line ... >=20 >=20 > I think we should have an interface similar to smbios for that eventual= ly. > Something where you can explicitly set arbitrary CPUID leaf information > using leaf specific syntax. There are more leafs where it would make se= nse - > cache topology for example. Right, separating cpuid from -cpu makes it bearable, like -cpuid leaf=3D%x[,subleaf=3D%x][,eax=3D%x][,ebx=3D%x][,ecx=3D%x][,edx=3D= %x] And Having multiple interfaces for the same thing would result in some corner case decisions ... I think QEMU should check that feature flags specified flags specified by -cpu are not cleared by -cpuid. I'm not sure if setters like "|=3D" and "&=3D~" would be beneficial in so= me cases.