On Tue, Apr 27, 2010 at 10:30:48AM -0300, Marcelo Tosatti wrote: > On Mon, Apr 26, 2010 at 01:46:26PM -0400, Glauber Costa wrote: > > Since we're changing the msrs kvmclock uses, we have to communicate > > that to the guest, through cpuid. We can add a new KVM_CAP to the > > hypervisor, and then patch userspace to recognize it. > > > > 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. > > > > Instead, what I'm proposing in this patch is a new capability, called > > KVM_CAP_X86_CPUID_FEATURE_LIST, that returns the current feature list > > currently supported by the hypervisor. If we ever want to add or remove > > some feature, we only need to tweak into the HV, leaving userspace untouched. > > > > Signed-off-by: Glauber Costa <glommer@xxxxxxxxxx> > > --- > > arch/x86/include/asm/kvm_para.h | 4 ++++ > > arch/x86/kvm/x86.c | 6 ++++++ > > include/linux/kvm.h | 1 + > > 3 files changed, 11 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 > > > > #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 a2ead7f..04f04aa 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -1545,6 +1545,12 @@ int kvm_dev_ioctl_check_extension(long ext) > > case KVM_CAP_MCE: > > r = KVM_MAX_MCE_BANKS; > > break; > > + case KVM_CAP_X86_CPUID_FEATURE_LIST: > > + r = (1 << KVM_FEATURE_CLOCKSOURCE) | > > + (1 << KVM_FEATURE_NOP_IO_DELAY) | > > + (1 << KVM_FEATURE_MMU_OP) | > > Remove this flag, it has been deprecated. Ok, sorry. My bad here. at a quick glance, I did not realize you were commenting on this patch specifically. KVM_CAP_X86_CPUID_FEATURE_LIST is a new entity, so there is no need to return a deprecated feature. I will remove that. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
