On 09/10/2014 08:13 PM, Christoffer Dall wrote:
> On Tue, Aug 26, 2014 at 05:05:41PM -0700, Mario Smarduch wrote:
>> This patch adds support for handling 2nd stage page faults during migration,
>> it disables faulting in huge pages, and dissolves huge pages to page tables.
>> In case migration is canceled huge pages may be used again.
>>
>> Signed-off-by: Mario Smaduch <m.smarduch@xxxxxxxxxxx>
>> ---
>> arch/arm/kvm/mmu.c | 45 +++++++++++++++++++++++++++++++++++++++------
>> 1 file changed, 39 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
>> index f176edf..0d79db04 100644
>> --- a/arch/arm/kvm/mmu.c
>> +++ b/arch/arm/kvm/mmu.c
>> @@ -47,6 +47,15 @@ static phys_addr_t hyp_idmap_vector;
>> #define kvm_pmd_huge(_x) (pmd_huge(_x) || pmd_trans_huge(_x))
>> #define kvm_pud_huge(_x) pud_huge(_x)
>>
>> +static bool kvm_get_logging_state(unsigned long *dirty_bitmap)
>
> this would seem slightly more sane if it took a memslot as its
> parameter.
Yes it would :) will update.
>> +{
>> +#ifdef CONFIG_ARM
>> + return !!dirty_bitmap;
>> +#else
>> + return false;
>> +#endif
>> +}
>> +
>> static void kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
>> {
>> /*
>> @@ -626,7 +635,8 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
>> }
>>
>> static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
>> - phys_addr_t addr, const pte_t *new_pte, bool iomap)
>> + phys_addr_t addr, const pte_t *new_pte, bool iomap,
>> + bool logging_active)
>> {
>> pmd_t *pmd;
>> pte_t *pte, old_pte;
>> @@ -641,6 +651,18 @@ static int stage2_set_pte(struct kvm *kvm, struct kvm_mmu_memory_cache *cache,
>> return 0;
>> }
>>
>> + /*
>> + * While dirty memory logging, clear PMD entry for huge page and split
>> + * into smaller pages, to track dirty memory at page granularity.
>> + */
>> + if (logging_active && kvm_pmd_huge(*pmd)) {
>> + phys_addr_t ipa = pmd_pfn(*pmd) << PAGE_SHIFT;
>> +
>> + pmd_clear(pmd);
>> + kvm_tlb_flush_vmid_ipa(kvm, ipa);
>> + put_page(virt_to_page(pmd));
>> + }
>> +
>> /* Create stage-2 page mappings - Level 2 */
>> if (pmd_none(*pmd)) {
>> if (!cache)
>> @@ -693,7 +715,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
>> if (ret)
>> goto out;
>> spin_lock(&kvm->mmu_lock);
>> - ret = stage2_set_pte(kvm, &cache, addr, &pte, true);
>> + ret = stage2_set_pte(kvm, &cache, addr, &pte, true, false);
>> spin_unlock(&kvm->mmu_lock);
>> if (ret)
>> goto out;
>> @@ -909,6 +931,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>> struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
>> struct vm_area_struct *vma;
>> pfn_t pfn;
>> + bool logging_active = kvm_get_logging_state(memslot->dirty_bitmap);
>>
>> write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu));
>> if (fault_status == FSC_PERM && !write_fault) {
>> @@ -919,7 +942,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>> /* Let's check if we will get back a huge page backed by hugetlbfs */
>> down_read(¤t->mm->mmap_sem);
>> vma = find_vma_intersection(current->mm, hva, hva + 1);
>> - if (is_vm_hugetlb_page(vma)) {
>> + if (is_vm_hugetlb_page(vma) && !logging_active) {
>> hugetlb = true;
>> gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
>> } else {
>> @@ -962,7 +985,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>> spin_lock(&kvm->mmu_lock);
>> if (mmu_notifier_retry(kvm, mmu_seq))
>> goto out_unlock;
>> - if (!hugetlb && !force_pte)
>> + if (!hugetlb && !force_pte && !logging_active)
>> hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);
>>
>> if (hugetlb) {
>> @@ -981,9 +1004,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>> kvm_set_pfn_dirty(pfn);
>> }
>> coherent_cache_guest_page(vcpu, hva, PAGE_SIZE);
>> - ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, false);
>> + ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, false,
>> + logging_active);
>> }
>>
>> + if (write_fault)
>> + mark_page_dirty(kvm, gfn);
>>
>> out_unlock:
>> spin_unlock(&kvm->mmu_lock);
>> @@ -1134,7 +1160,14 @@ static void kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, void *data)
>> {
>> pte_t *pte = (pte_t *)data;
>>
>> - stage2_set_pte(kvm, NULL, gpa, pte, false);
>> + /*
>> + * We can always call stage2_set_pte with logging_active == false,
>> + * because MMU notifiers will have unmapped a huge PMD before calling
>> + * ->change_pte() (which in turn calls kvm_set_spte_hva()) and therefore
>> + * stage2_set_pte() never needs to clear out a huge PMD through this
>> + * calling path.
>> + */
>> + stage2_set_pte(kvm, NULL, gpa, pte, false, false);
>> }
>>
>>
>
> Assuming you address the nit:
>
> Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
>
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