On 16.02.2018 15:35, Janosch Frank wrote:
> On 16.02.2018 15:30, David Hildenbrand wrote:
>> On 16.02.2018 12:16, Janosch Frank wrote:
>>> Up to now we always expected to have the storage key facility
>>> available for our (non-VSIE) KVM guests. For huge page support, we
>>> need to be able to disable it, so let's introduce that now.
>>>
>>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
>>> Reviewed-by: Farhan Ali <alifm@xxxxxxxxxxxxxxxxxx>
>>> ---
>>> arch/s390/include/asm/kvm_host.h | 1 +
>>> arch/s390/include/asm/mmu.h | 2 +-
>>> arch/s390/include/asm/mmu_context.h | 2 +-
>>> arch/s390/include/asm/pgtable.h | 4 ++--
>>> arch/s390/kvm/kvm-s390.c | 3 ++-
>>> arch/s390/kvm/priv.c | 22 +++++++++++++---------
>>> arch/s390/mm/gmap.c | 6 +++---
>>> arch/s390/mm/pgtable.c | 4 ++--
>>> 8 files changed, 25 insertions(+), 19 deletions(-)
>>>
>>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>>> index 27918b1..f161ad0 100644
>>> --- a/arch/s390/include/asm/kvm_host.h
>>> +++ b/arch/s390/include/asm/kvm_host.h
>>> @@ -793,6 +793,7 @@ struct kvm_arch{
>>> int use_irqchip;
>>> int use_cmma;
>>> int use_pfmfi;
>>> + int use_skf;
>>> int user_cpu_state_ctrl;
>>> int user_sigp;
>>> int user_stsi;
>>> diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h
>>> index c639c95..f5ff9db 100644
>>> --- a/arch/s390/include/asm/mmu.h
>>> +++ b/arch/s390/include/asm/mmu.h
>>> @@ -21,7 +21,7 @@ typedef struct {
>>> /* The mmu context uses extended page tables. */
>>> unsigned int has_pgste:1;
>>> /* The mmu context uses storage keys. */
>>> - unsigned int use_skey:1;
>>> + unsigned int uses_skeys:1;
>>> /* The mmu context uses CMM. */
>>> unsigned int uses_cmm:1;
>>> } mm_context_t;
>>> diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
>>> index d3ebfa8..bc9a2a9 100644
>>> --- a/arch/s390/include/asm/mmu_context.h
>>> +++ b/arch/s390/include/asm/mmu_context.h
>>> @@ -30,7 +30,7 @@ static inline int init_new_context(struct task_struct *tsk,
>>> test_thread_flag(TIF_PGSTE) ||
>>> (current->mm && current->mm->context.alloc_pgste);
>>> mm->context.has_pgste = 0;
>>> - mm->context.use_skey = 0;
>>> + mm->context.uses_skeys = 0;
>>> mm->context.uses_cmm = 0;
>>> #endif
>>> switch (mm->context.asce_limit) {
>>> diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
>>> index 9223b4d..4f26425 100644
>>> --- a/arch/s390/include/asm/pgtable.h
>>> +++ b/arch/s390/include/asm/pgtable.h
>>> @@ -509,10 +509,10 @@ static inline int mm_alloc_pgste(struct mm_struct *mm)
>>> * faults should no longer be backed by zero pages
>>> */
>>> #define mm_forbids_zeropage mm_has_pgste
>>> -static inline int mm_use_skey(struct mm_struct *mm)
>>> +static inline int mm_uses_skeys(struct mm_struct *mm)
>>> {
>>> #ifdef CONFIG_PGSTE
>>> - if (mm->context.use_skey)
>>> + if (mm->context.uses_skeys)
>>> return 1;
>>> #endif
>>> return 0;
>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>>> index 8fb6549..90deb7b 100644
>>> --- a/arch/s390/kvm/kvm-s390.c
>>> +++ b/arch/s390/kvm/kvm-s390.c
>>> @@ -1432,7 +1432,7 @@ static long kvm_s390_get_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
>>> return -EINVAL;
>>>
>>> /* Is this guest using storage keys? */
>>> - if (!mm_use_skey(current->mm))
>>> + if (!mm_uses_skeys(current->mm))
>>> return KVM_S390_GET_SKEYS_NONE;
>>>
>>> /* Enforce sane limit on memory allocation */
>>> @@ -2010,6 +2010,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>>> kvm->arch.css_support = 0;
>>> kvm->arch.use_irqchip = 0;
>>> kvm->arch.use_pfmfi = sclp.has_pfmfi;
>>> + kvm->arch.use_skf = sclp.has_skey;
>>> kvm->arch.epoch = 0;
>>>
>>> spin_lock_init(&kvm->arch.start_stop_lock);
>>> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
>>> index 76a2380..d9bd147 100644
>>> --- a/arch/s390/kvm/priv.c
>>> +++ b/arch/s390/kvm/priv.c
>>> @@ -208,19 +208,23 @@ int kvm_s390_skey_check_enable(struct kvm_vcpu *vcpu)
>>> struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;
>>>
>>> trace_kvm_s390_skey_related_inst(vcpu);
>>> - if (!(sie_block->ictl & (ICTL_ISKE | ICTL_SSKE | ICTL_RRBE)) &&
>>> + /* Already enabled? */
>>> + if (vcpu->kvm->arch.use_skf &&
>>> + !(sie_block->ictl & (ICTL_ISKE | ICTL_SSKE | ICTL_RRBE)) &&
>>> !kvm_s390_test_cpuflags(vcpu, CPUSTAT_KSS))
>>> return rc;
>>
>> While at it, can you directly "return 0;" here and remove the
>> initialization of rc to 0? Makes the code easier to read
>
> Sure
>
>>
>>>
>>> rc = s390_enable_skey();
>>> VCPU_EVENT(vcpu, 3, "enabling storage keys for guest: %d", rc);
>>> - if (!rc) {
>>> - if (kvm_s390_test_cpuflags(vcpu, CPUSTAT_KSS))
>>> - kvm_s390_clear_cpuflags(vcpu, CPUSTAT_KSS);
>>> - else
>>> - sie_block->ictl &= ~(ICTL_ISKE | ICTL_SSKE |
>>> - ICTL_RRBE);
>>> - }
>>> + if (rc)
>>> + return rc;
>>> +
>>> + if (kvm_s390_test_cpuflags(vcpu, CPUSTAT_KSS))
>>> + kvm_s390_clear_cpuflags(vcpu, CPUSTAT_KSS);
>>> + if (!vcpu->kvm->arch.use_skf)
>>> + sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
>>> + else
>>> + sie_block->ictl &= ~(ICTL_ISKE | ICTL_SSKE | ICTL_RRBE);
>>
>>
>> I wonder why
>>
>> vcpu->arch.sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
>>
>> Is set conditionally (sclp.has_kss) in kvm_arch_vcpu_setup().
>>
>> Can't we simply always set these bits there and only clear them here
>> conditionally?
>
> Intercept priority... skey intercepts are more important than kss.
>
... but does that make any difference here?
--
Thanks,
David / dhildenb
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