On Tue, 6 Mar 2018 14:27:58 +0100
David Hildenbrand <david@xxxxxxxxxx> wrote:
> Even if we don't have extended SCA support, we can have more than 64 CPUs
> if we don't enable any HW features that might use the SCA entries.
>
> Now, this works just fine, but we missed a return, which is why we
> would actually store the SCA entries. If we have more than 64 CPUs, this
> means writing outside of the basic SCA - bad.
>
> Let's fix this. This allows > 64 CPUs when running nested (under vSIE)
> without random crashes.
>
> Fixes: a6940674c384 ("KVM: s390: allow 255 VCPUs when sca entries aren't used")
cc: stable?
> Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Tested-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> ---
> arch/s390/kvm/kvm-s390.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 77d7818130db..321bfbc67d3d 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2146,6 +2146,7 @@ static void sca_add_vcpu(struct kvm_vcpu *vcpu)
> /* we still need the basic sca for the ipte control */
> vcpu->arch.sie_block->scaoh = (__u32)(((__u64)sca) >> 32);
> vcpu->arch.sie_block->scaol = (__u32)(__u64)sca;
> + return;
> }
> read_lock(&vcpu->kvm->arch.sca_lock);
> if (vcpu->kvm->arch.use_esca) {
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
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