Messages in this thread Patch in this message | | | Date | Sun, 13 Feb 2011 17:12:14 +0200 | From | Avi Kivity <> | Subject | Re: [PATCH 6/6] KVM: X86: Implement userspace interface to set virtual_tsc_khz |
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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@amd.com> > --- > 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.
-- error compiling committee.c: too many arguments to function
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