From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:35847) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TrqdI-0004P1-Mq for qemu-devel@nongnu.org; Sun, 06 Jan 2013 08:51:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TrqdH-0002Bc-Lw for qemu-devel@nongnu.org; Sun, 06 Jan 2013 08:51:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:3720) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TrqdH-0002BS-EG for qemu-devel@nongnu.org; Sun, 06 Jan 2013 08:51:23 -0500 Date: Sun, 6 Jan 2013 15:51:17 +0200 From: Gleb Natapov Message-ID: <20130106135117.GG3440@redhat.com> References: <1357336872-7200-1-git-send-email-ehabkost@redhat.com> <1357336872-7200-4-git-send-email-ehabkost@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1357336872-7200-4-git-send-email-ehabkost@redhat.com> Subject: Re: [Qemu-devel] [PATCH qom-cpu 03/11] target-i386: kvm: -cpu host: Use GET_SUPPORTED_CPUID for SVM features List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: kvm@vger.kernel.org, libvir-list@redhat.com, Joerg Roedel , Marcelo Tosatti , qemu-devel@nongnu.org, Igor Mammedov , Andreas =?utf-8?Q?F=C3=A4rber?= On Fri, Jan 04, 2013 at 08:01:04PM -0200, Eduardo Habkost wrote: > The existing -cpu host code simply set every bit inside svm_features > (initializing it to -1), and that makes it impossible to make the > enforce/check options work properly when the user asks for SVM features > explicitly in the command-line. > > So, instead of initializing svm_features to -1, use GET_SUPPORTED_CPUID > to fill only the bits that are supported by the host (just like we do > for all other CPUID feature words inside kvm_cpu_fill_host()). > > This will keep the existing behavior (as filter_features_for_kvm() > already uses GET_SUPPORTED_CPUID to filter svm_features), but will allow > us to properly check for KVM features inside > kvm_check_features_against_host() later. > > For example, we will be able to make this: > > $ qemu-system-x86_64 -cpu ...,+pfthreshold,enforce > > refuse to start if the SVM "pfthreshold" feature is not supported by the > host (after we fix kvm_check_features_against_host() to check SVM flags > as well). > > Signed-off-by: Eduardo Habkost Reviewed-by: Gleb Natapov > --- > Changes v2: > - Coding style (indentation) fix > > Cc: Gleb Natapov > Cc: Marcelo Tosatti > Cc: Joerg Roedel > Cc: kvm@vger.kernel.org > --- > target-i386/cpu.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c > index c83a566..c49a97c 100644 > --- a/target-i386/cpu.c > +++ b/target-i386/cpu.c > @@ -908,13 +908,10 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def) > } > } > > - /* > - * Every SVM feature requires emulation support in KVM - so we can't just > - * read the host features here. KVM might even support SVM features not > - * available on the host hardware. Just set all bits and mask out the > - * unsupported ones later. > - */ > - x86_cpu_def->svm_features = -1; > + /* Other KVM-specific feature fields: */ > + x86_cpu_def->svm_features = > + kvm_arch_get_supported_cpuid(s, 0x8000000A, 0, R_EDX); > + > #endif /* CONFIG_KVM */ > } > > -- > 1.7.11.7 -- Gleb.