On 02/19/2018 12:20 PM, David Hildenbrand wrote:
> On 19.02.2018 09:53, Christian Borntraeger wrote:
>> Some facilities should only provided to the guest, if these are
>> enabled by a CPU model. This allows to avoid capabilities and
>> simply fallback to the cpumodel for deciding about a facility
>> without enabling it for older QEMUs or QEMUs without a CPU
>> model.
>>
>> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>> ---
>> arch/s390/kvm/kvm-s390.c | 40 ++++++++++++++++++++++++++++++++--------
>> arch/s390/kvm/kvm-s390.h | 2 --
>> arch/s390/tools/gen_facilities.c | 20 ++++++++++++++++++++
>> 3 files changed, 52 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index 5b7fe80cda56..7d982690b1fc 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -151,13 +151,27 @@ static int nested;
>> module_param(nested, int, S_IRUGO);
>> MODULE_PARM_DESC(nested, "Nested virtualization support");
>>
>> -/* upper facilities limit for kvm */
>> -unsigned long kvm_s390_fac_list_mask[16] = { FACILITIES_KVM };
>>
>> -unsigned long kvm_s390_fac_list_mask_size(void)
>> +/*
>> + * For now we handle not more than 16 double words as this is what
>> + * the s390 base kernel handles and stores in prefix page. If we
>> + * ever need to go beyond this, this requires changes to code, but
>> + * the external uapi can stay.
>> + */
>> +#define SIZE_INTERNAL 16
>> +
>> +/* upper facilities limit for kvm */
>> +static unsigned long kvm_s390_fac_list_mask[SIZE_INTERNAL] = { FACILITIES_KVM };
>> +/*
>> + * facility bits that are in the mask, but initially not in the list.
>> + * Those can be activated by the CPU model
>> + */
>> +static unsigned long kvm_s390_fac_model[SIZE_INTERNAL] = { FACILITIES_KVM_CPUMODEL };
>
> _list_mask vs _model
>
> Can we make this more consistent?
I will try.
>
>
>> +
>> +static unsigned long kvm_s390_fac_size(void)
>> {
>> - BUILD_BUG_ON(ARRAY_SIZE(kvm_s390_fac_list_mask) > S390_ARCH_FAC_MASK_SIZE_U64);
>> - return ARRAY_SIZE(kvm_s390_fac_list_mask);
>> + BUILD_BUG_ON(SIZE_INTERNAL > S390_ARCH_FAC_MASK_SIZE_U64);
>> + return SIZE_INTERNAL;
>> }
>>
>> /* available cpu features supported by kvm */
>> @@ -1946,17 +1960,27 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>> memcpy(kvm->arch.model.fac_mask, S390_lowcore.stfle_fac_list,
>> sizeof(S390_lowcore.stfle_fac_list));
>> for (i = 0; i < S390_ARCH_FAC_LIST_SIZE_U64; i++) {
>> - if (i < kvm_s390_fac_list_mask_size())
>> - kvm->arch.model.fac_mask[i] &= kvm_s390_fac_list_mask[i];
>> + if (i < kvm_s390_fac_size())
>> + kvm->arch.model.fac_mask[i] &= (kvm_s390_fac_list_mask[i] |
>> + kvm_s390_fac_model[i]);
>> else
>> kvm->arch.model.fac_mask[i] = 0UL;
>> }
>>
>> - /* Populate the facility list initially. */
>> + /* Populate the facility list initially as a copy of the mask */
>> kvm->arch.model.fac_list = kvm->arch.sie_page2->fac_list;
>> memcpy(kvm->arch.model.fac_list, kvm->arch.model.fac_mask,
>> S390_ARCH_FAC_LIST_SIZE_BYTE);
>>
>
> If you need a loop either way, why not simply drop the memcpy and
> instead do it explicitly in a single loop?
Yes, can do. I will also remove the zeroing (as in your other patch). To do that I need
to limit kvm_s390_fac_list_mask_size to not exceed sizeof(S390_lowcore.stfle_fac_list)
though.
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