Re: [Qemu-devel] [PATCH 2/9] kvm: add kvm_enable_cap_{vm,vcpu}

[Alexander Graf]

On 14.04.14 18:48, Cornelia Huck wrote:
> Provide helper functions for enabling capabilities (on a vcpu and on a vm).
>
> Reviewed-by: Thomas Huth <address@hidden>
> Signed-off-by: Cornelia Huck <address@hidden>
> ---
>   include/sysemu/kvm.h |    4 ++++
>   kvm-all.c            |   33 ++++++++++++++++++++++++++++++++-
>   2 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 0bee1e8..2ff5ad3 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -294,6 +294,10 @@ bool kvm_arch_stop_on_emulation_error(CPUState *cpu);
>   
>   int kvm_check_extension(KVMState *s, unsigned int extension);
>   
> +int kvm_enable_cap_vm(KVMState *s, unsigned int capability, ...);
> +
> +int kvm_enable_cap_vcpu(CPUState *cpu, unsigned int capability, ...);
> +
>   uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
>                                         uint32_t index, int reg);
>   
> diff --git a/kvm-all.c b/kvm-all.c
> index cd4111d..658e50c 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -501,7 +501,38 @@ int kvm_check_extension(KVMState *s, unsigned int 
> extension)
>       return ret;
>   }
>   
> -static int kvm_set_ioeventfd_mmio(int fd, hwaddr addr, uint32_t val,
> +int kvm_enable_cap_vm(KVMState *s, unsigned int capability, ...)
> +{
> +    struct kvm_enable_cap cap = {};
> +    va_list ap;
> +    int i;
> +
> +    cap.cap = capability;
> +    va_start(ap, capability);
> +    for (i = 0; i < 4; i++) {
> +        cap.args[i] = va_arg(ap, uint64_t);

Is this legit? Can we just pull items off the stack without running beyond?


Alex

> +    }
> +    va_end(ap);
> +    return kvm_vm_ioctl(s, KVM_ENABLE_CAP, &cap);
> +}
> +
> +int kvm_enable_cap_vcpu(CPUState *cpu, unsigned int capability, ...)
> +{
> +    struct kvm_enable_cap cap = {};
> +    va_list ap;
> +    int i;
> +
> +    cap.cap = capability;
> +    va_start(ap, capability);
> +    for (i = 0; i < 4; i++) {
> +        cap.args[i] = va_arg(ap, uint64_t);
> +    }
> +    va_end(ap);
> +    return kvm_vcpu_ioctl(cpu, KVM_ENABLE_CAP, &cap);
> +}
> +
> +
> +static int kvm_set_ioeventfd_mmio(int fd, uint32_t addr, uint32_t val,
>                                     bool assign, uint32_t size, bool datamatch)
>   {
>       int ret;