On Wed, 1 Aug 2018 12:25:08 +0100
Janosch Frank <frankja@xxxxxxxxxxxxx> wrote:
s/vms/VMs/ ? (throughout the patch description)
Otherwise, I keep wondering about supporting vms on s390 :)
> We currently do not notify all gmaps when using gmap_pmdp_xchg(), due
> to locking constraints. This makes ucontrol vms, which is the only vm
> type that creates multiple gmaps, incompatible with huge pages.
>
> ucontrol vms are rather exotic and creating a new locking concept is
> no easy task. Hence we return EINVAL when trying to active
> KVM_CAP_S390_HPAGE_1M and report it as being not available when
> checking for it.
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> ---
> arch/s390/kvm/kvm-s390.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index f9d90337e64a..549f38d1baa1 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -481,7 +481,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> break;
> case KVM_CAP_S390_HPAGE_1M:
> r = 0;
> - if (hpage)
> + if (hpage && !kvm_is_ucontrol(kvm))
> r = 1;
> break;
> case KVM_CAP_S390_MEM_OP:
> @@ -691,7 +691,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
> mutex_lock(&kvm->lock);
> if (kvm->created_vcpus)
> r = -EBUSY;
> - else if (!hpage || kvm->arch.use_cmma)
> + else if (!hpage || kvm->arch.use_cmma || kvm_is_ucontrol(kvm))
> r = -EINVAL;
> else {
> r = 0;
Update the documentation for the cap as well?
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