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. The deprecation of this flag has nothing to do with this series. Anyway, we can't pick its number, even if it is really deprecated, since we can still have old hvs around, so, don't really see the point here > > > + (1 << KVM_FEATURE_CLOCKSOURCE2); > > + break; > > default: > > Also missing qemu-kvm/qemu patches. > Of course it is missing. It is a totally separate story. -- 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
