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SubjectRe: [PATCH 6/6] KVM: X86: Implement userspace interface to set virtual_tsc_khz
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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