On Sun, Feb 13, 2011 at 10:12:14AM -0500, Avi Kivity wrote:
> On 02/09/2011 07:29 PM, Joerg Roedel wrote:
> > This patch implements two new vm-ioctls to get and set the
> > virtual_tsc_khz if the machine supports tsc-scaling. Setting
> > the tsc-frequency is only possible before userspace creates
> > any vcpu.
> >
> > Signed-off-by: Joerg Roedel<joerg.roedel@xxxxxxx>
> > ---
> > arch/x86/include/asm/kvm_host.h | 1 +
> > arch/x86/kvm/svm.c | 3 +++
> > arch/x86/kvm/x86.c | 38 ++++++++++++++++++++++++++++++++++++++
> > include/linux/kvm.h | 4 ++++
> > 4 files changed, 46 insertions(+), 0 deletions(-)
> >
>
> Documentation/kvm/api.txt +++++++++++++
>
> > @@ -633,6 +633,7 @@ int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
> > u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
> >
> > extern bool tdp_enabled;
> > +extern int kvm_has_tsc_control;
>
> bool
>
>
> > + case KVM_SET_TSC_KHZ: {
> > + u32 user_tsc_khz;
> > +
> > + if (!kvm_has_tsc_control)
> > + break;
> > +
> > + /*
> > + * We force the tsc frequency to be set before any
> > + * vcpu is created
> > + */
> > + if (atomic_read(&kvm->online_vcpus)> 0)
> > + goto out;
>
> What if a vcpu is created here? No locking AFAICS.
>
> > +
> > + user_tsc_khz = arg;
> > +
> > + kvm_arch_set_tsc_khz(kvm, user_tsc_khz);
> > +
>
> Error check for impossible values (0, values the tsc multiplier can't
> reach)?
>
> > + r = 0;
> > + goto out;
> > + }
> > + case KVM_GET_TSC_KHZ: {
> > +
> > + if (!kvm_has_tsc_control)
> > + break;
> > +
> > + r = -EFAULT;
> > + if (copy_to_user(argp,&kvm->arch.virtual_tsc_khz, sizeof(__u32)))
> > + goto out;
>
> Should be the return value, no?
>
> > +
> > + r = 0;
> > + goto out;
> > + }
> >
> > default:
> > ;
> >
> >
> > @@ -677,6 +678,9 @@ struct kvm_clock_data {
> > #define KVM_SET_PIT2 _IOW(KVMIO, 0xa0, struct kvm_pit_state2)
> > /* Available with KVM_CAP_PPC_GET_PVINFO */
> > #define KVM_PPC_GET_PVINFO _IOW(KVMIO, 0xa1, struct kvm_ppc_pvinfo)
> > +/* Available with KVM_CAP_TSC_CONTROL */
> > +#define KVM_SET_TSC_KHZ _IOW(KVMIO, 0xa2, __u32)
> > +#define KVM_GET_TSC_KHZ _IOR(KVMIO, 0xa3, __u32)
> >
>
> _IO() - use arg or return value
> _IOW/_IOR - copy_to/from_user()
>
> pick one, but don't mix.
Thanks, I'll fix these issued in the next version.
Regards,
Joerg
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