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.
>
>
>> return rc;
>> }
>>
>> @@ -231,7 +235,7 @@ static int try_handle_skey(struct kvm_vcpu *vcpu)
>> rc = kvm_s390_skey_check_enable(vcpu);
>> if (rc)
>> return rc;
>> - if (sclp.has_skey) {
>> + if (vcpu->kvm->arch.use_skf) {
>> /* with storage-key facility, SIE interprets it for us */
>> kvm_s390_retry_instr(vcpu);
>> VCPU_EVENT(vcpu, 4, "%s", "retrying storage key operation");
>> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
>> index 2cafcba..dbdcd25 100644
>> --- a/arch/s390/mm/gmap.c
>> +++ b/arch/s390/mm/gmap.c
>> @@ -3094,14 +3094,14 @@ int s390_enable_skey(void)
>> int rc = 0;
>>
>> down_write(&mm->mmap_sem);
>> - if (mm_use_skey(mm))
>> + if (mm_uses_skeys(mm))
>> goto out_up;
>>
>> - mm->context.use_skey = 1;
>> + mm->context.uses_skeys = 1;
>> for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
>> MADV_UNMERGEABLE, &vma->vm_flags)) {
>> - mm->context.use_skey = 0;
>> + mm->context.uses_skeys = 0;
>> rc = -ENOMEM;
>> goto out_up;
>> }
>> diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
>> index 871fc65..158c880 100644
>> --- a/arch/s390/mm/pgtable.c
>> +++ b/arch/s390/mm/pgtable.c
>> @@ -158,7 +158,7 @@ static inline pgste_t pgste_update_all(pte_t pte, pgste_t pgste,
>> #ifdef CONFIG_PGSTE
>> unsigned long address, bits, skey;
>>
>> - if (!mm_use_skey(mm) || pte_val(pte) & _PAGE_INVALID)
>> + if (!mm_uses_skeys(mm) || pte_val(pte) & _PAGE_INVALID)
>> return pgste;
>> address = pte_val(pte) & PAGE_MASK;
>> skey = (unsigned long) page_get_storage_key(address);
>> @@ -180,7 +180,7 @@ static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry,
>> unsigned long address;
>> unsigned long nkey;
>>
>> - if (!mm_use_skey(mm) || pte_val(entry) & _PAGE_INVALID)
>> + if (!mm_uses_skeys(mm) || pte_val(entry) & _PAGE_INVALID)
>> return;
>> VM_BUG_ON(!(pte_val(*ptep) & _PAGE_INVALID));
>> address = pte_val(entry) & PAGE_MASK;
>>
>
>
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