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.