Re: [Qemu-ppc] [PATCH 1/2] target-ppc/kvm: Add a wrapper function to check for KVM-PR

[David Gibson]

On Thu, Sep 29, 2016 at 12:48:06PM +0200, Thomas Huth wrote:
> It makes more sense if we have a proper function to check
> for KVM-PR than to check for the GET_PVINFO extension all
> over the place.
> 
> Signed-off-by: Thomas Huth <address@hidden>

Applied to ppc-for-2.8.  I expanded your comment to say this should
only be used for fallback tests, though.

> ---
>  target-ppc/kvm.c | 23 +++++++++++++----------
>  1 file changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
> index e9a9faf..dca50bc 100644
> --- a/target-ppc/kvm.c
> +++ b/target-ppc/kvm.c
> @@ -102,6 +102,13 @@ static void kvm_kick_cpu(void *opaque)
>      qemu_cpu_kick(CPU(cpu));
>  }
>  
> +/* Check whether we are running with KVM-PR (instead of KVM-HV) */
> +static bool kvmppc_is_pr(KVMState *ks)
> +{
> +    /* Assume KVM-PR if the GET_PVINFO capability is available */
> +    return kvm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
> +}
> +
>  static int kvm_ppc_register_host_cpu_type(void);
>  
>  int kvm_arch_init(MachineState *ms, KVMState *s)
> @@ -223,10 +230,9 @@ static void kvm_get_fallback_smmu_info(PowerPCCPU *cpu,
>       *
>       * For that to work we make a few assumptions:
>       *
> -     * - If KVM_CAP_PPC_GET_PVINFO is supported we are running "PR"
> -     *   KVM which only supports 4K and 16M pages, but supports them
> -     *   regardless of the backing store characteritics. We also don't
> -     *   support 1T segments.
> +     * - Check whether we are running "PR" KVM which only supports 4K
> +     *   and 16M pages, but supports them regardless of the backing
> +     *   store characteritics. We also don't support 1T segments.
>       *
>       *   This is safe as if HV KVM ever supports that capability or PR
>       *   KVM grows supports for more page/segment sizes, those versions
> @@ -241,7 +247,7 @@ static void kvm_get_fallback_smmu_info(PowerPCCPU *cpu,
>       *   implements KVM_CAP_PPC_GET_SMMU_INFO and thus doesn't hit
>       *   this fallback.
>       */
> -    if (kvm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_PVINFO)) {
> +    if (kvmppc_is_pr(cs->kvm_state)) {
>          /* No flags */
>          info->flags = 0;
>          info->slb_size = 64;
> @@ -2270,11 +2276,8 @@ int kvmppc_reset_htab(int shift_hint)
>  
>      /* We have a kernel that predates the htab reset calls.  For PR
>       * KVM, we need to allocate the htab ourselves, for an HV KVM of
> -     * this era, it has allocated a 16MB fixed size hash table
> -     * already.  Kernels of this era have the GET_PVINFO capability
> -     * only on PR, so we use this hack to determine the right
> -     * answer */
> -    if (kvm_check_extension(kvm_state, KVM_CAP_PPC_GET_PVINFO)) {
> +     * this era, it has allocated a 16MB fixed size hash table already. */
> +    if (kvmppc_is_pr(kvm_state)) {
>          /* PR - tell caller to allocate htab */
>          return 0;
>      } else {

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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