From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933537Ab0EEIXd (ORCPT ); Wed, 5 May 2010 04:23:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48771 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932155Ab0EEIXb (ORCPT ); Wed, 5 May 2010 04:23:31 -0400 Message-ID: <4BE12B00.803@redhat.com> Date: Wed, 05 May 2010 11:23:28 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Glauber Costa CC: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, zamsden@redhat.com Subject: Re: [PATCH v2 4/7] export paravirtual cpuid flags in KVM_GET_SUPPORTED_CPUID References: <1272901927-829-1-git-send-email-glommer@redhat.com> <1272901927-829-2-git-send-email-glommer@redhat.com> <1272901927-829-3-git-send-email-glommer@redhat.com> <1272901927-829-4-git-send-email-glommer@redhat.com> <1272901927-829-5-git-send-email-glommer@redhat.com> In-Reply-To: <1272901927-829-5-git-send-email-glommer@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/03/2010 06:52 PM, Glauber Costa wrote: > Right now, we were using individual KVM_CAP entities to communicate > userspace about which cpuids we support. This is suboptimal, since it > generates a delay between the feature arriving in the host, and > being available at the guest. > > A much better mechanism is to list para features in KVM_GET_SUPPORTED_CPUID. > This makes userspace automatically aware of what we provide. And if we > ever add a new cpuid bit in the future, we have to do that again, > which create some complexity and delay in feature adoption. > > Signed-off-by: Glauber Costa > --- > arch/x86/include/asm/kvm_para.h | 4 ++++ > arch/x86/kvm/x86.c | 27 +++++++++++++++++++++++++++ > 2 files changed, 31 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h > index 9734808..f019f8c 100644 > --- a/arch/x86/include/asm/kvm_para.h > +++ b/arch/x86/include/asm/kvm_para.h > @@ -16,6 +16,10 @@ > #define KVM_FEATURE_CLOCKSOURCE 0 > #define KVM_FEATURE_NOP_IO_DELAY 1 > #define KVM_FEATURE_MMU_OP 2 > +/* This indicates that the new set of kvmclock msrs > + * are available. The use of 0x11 and 0x12 is deprecated > + */ > +#define KVM_FEATURE_CLOCKSOURCE2 3 > Separate patch. > > #define MSR_KVM_WALL_CLOCK 0x11 > #define MSR_KVM_SYSTEM_TIME 0x12 > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index eb84947..8a7cdda 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1971,6 +1971,20 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > } > break; > } > + case 0x40000000: { > Use symbolic name, please. > + char signature[] = "KVMKVMKVM"; > + u32 *sigptr = (u32 *)signature; > + entry->eax = 1; > Where did this come from? > + entry->ebx = sigptr[0]; > + entry->ecx = sigptr[1]; > + entry->edx = sigptr[2]; > Overflow, you're reading 12 bytes from a 10-byte variable. > + break; > + } > + case 0x40000001: > + entry->eax = (1<< KVM_FEATURE_CLOCKSOURCE) | > + (1<< KVM_FEATURE_NOP_IO_DELAY) | > + (1<< KVM_FEATURE_CLOCKSOURCE2); > Indentation... Also, have to initialize all fields, since the real cpu won't initialize them for you. Sidenote: the real cpu may be a kvm vcpu, so it may in fact support those features. > + break; > case 0x80000000: > entry->eax = min(entry->eax, 0x8000001a); > break; > @@ -2017,6 +2031,19 @@ static int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid, > for (func = 0x80000001; func<= limit&& nent< cpuid->nent; ++func) > do_cpuid_ent(&cpuid_entries[nent], func, 0, > &nent, cpuid->nent); > + > + > + > + r = -E2BIG; > + if (nent>= cpuid->nent) > + goto out_free; > + > + do_cpuid_ent(&cpuid_entries[nent], 0x40000000, 0,&nent, cpuid->nent); > + limit = cpuid_entries[nent - 1].eax; > The kvm cpuid does not follow the limit thing. > + for (func = 0x40000001; func<= limit&& nent< cpuid->nent; ++func) > + do_cpuid_ent(&cpuid_entries[nent], func, 0, > + &nent, cpuid->nent); > + > r = -E2BIG; > To avoid confusion, please write Documentation/kvm/cpuid.txt based on the current qemu-kvm code, and implement this patch according to the documentation. -- error compiling committee.c: too many arguments to function