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. > + (1 << KVM_FEATURE_CLOCKSOURCE2); > + break; > default: Also missing qemu-kvm/qemu patches. -- 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
