Re: [PATCH 1/4] kvm: Add support for querying supported cpu features

Anthony Liguori
2009-05-08T20:50:21Z

Avi Kivity wrote:
> kvm does not support all cpu features; add support for dunamically querying
> the supported feature set.
>
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
> kvm.h | 3 ++
> target-i386/kvm.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 83 insertions(+), 0 deletions(-)
>
> diff --git a/kvm.h b/kvm.h
> index bd4e8d4..c134c45 100644
> --- a/kvm.h
> +++ b/kvm.h
> @@ -124,6 +124,9 @@ void kvm_arch_remove_all_hw_breakpoints(void);
>
> void kvm_arch_update_guest_debug(CPUState *env, struct kvm_guest_debug *dbg);
>
> +uint32_t kvm_arch_get_supported_cpuid(CPUState *env, uint32_t function,
> + int reg);
> +
> /* generic hooks - to be moved/refactored once there are more users */
>
> static inline void cpu_synchronize_state(CPUState *env, int modified)
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index b534b2d..5f54ff5 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -34,6 +34,86 @@
> do { } while (0)
> #endif
>
> +#ifdef KVM_CAP_EXT_CPUID
> +
> +static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max)
> +{
> + struct kvm_cpuid2 *cpuid;
> + int r, size;
> +
> + size = sizeof(*cpuid) + max * sizeof(*cpuid->entries);
> + cpuid = (struct kvm_cpuid2 *)qemu_mallocz(size);
> + cpuid->nent = max;
> + r = kvm_ioctl(s, KVM_GET_SUPPORTED_CPUID, cpuid);
> + if (r < 0) {
> + if (r == -E2BIG) {
> + qemu_free(cpuid);
> + return NULL;
> + } else {
> + fprintf(stderr, "KVM_GET_SUPPORTED_CPUID failed: %s\n",
> + strerror(-r));
> + exit(1);
> + }
> + }
> + return cpuid;
> +}
> +
> +uint32_t kvm_arch_get_supported_cpuid(CPUState *env, uint32_t function, int reg)
> +{
> + struct kvm_cpuid2 *cpuid;
> + int i, max;
> + uint32_t ret = 0;
> + uint32_t cpuid_1_edx;
> +
> + if (!kvm_check_extension(KVM_CAP_EXT_CPUID)) {
> + return -1U;
> +

kvm_check_extension doesn't exist in upstream QEMU. It's a good idea
though so I added it in a previous commit. However, I changed the
signature to it to take a KVMState * as the first argument (which is
available in env->kvm_state). I updated this patch to pass the extra
's' parameter.

Regards,

Anthony Liguori

--
Regards,

Anthony Liguori