On 19.02.2018 12:16, Christian Borntraeger wrote:
>
>
> On 02/16/2018 03:46 PM, David Hildenbrand wrote:
>> 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?
>
> The priority makes a difference for vsie. I think it makes sense to
> keep this is sync (e.g. if everybody has kss, really use kss and not
> the ictl variants).
>
Yes, it matters for vSIE (ICPT_KSS over ICPT_INST).
Simply always setting the icpt controls if !SKF makes it less error
prone. Not sure if it makes sense to keep this in sync here - the
priority handling really is just a way to get vSIE priorities right. For
!vSIE code we don't care at all.
--
Thanks,
David / dhildenb
