This patch adds support for handling 2nd stage page faults during migration, it disables faulting in huge pages, and splits up existing huge pages.
Signed-off-by: Mario Smarduch <[email protected]> --- arch/arm/kvm/mmu.c | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index b939312..10e7bf6 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1002,6 +1002,7 @@ 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 migration_active; write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu)); if (fault_status == FSC_PERM && !write_fault) { @@ -1053,12 +1054,23 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, return -EFAULT; spin_lock(&kvm->mmu_lock); + + /* + * Place inside lock to prevent race condition when whole VM is being + * write proteced. Prevent race of huge page install when migration is + * active. + */ + migration_active = vcpu->kvm->arch.migration_in_progress; + if (mmu_notifier_retry(kvm, mmu_seq)) goto out_unlock; - if (!hugetlb && !force_pte) + + /* When migrating don't spend cycles coalescing huge pages */ + if (!hugetlb && !force_pte && !migration_active) hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa); - if (hugetlb) { + /* During migration don't install huge pages */ + if (hugetlb && !migration_active) { pmd_t new_pmd = pfn_pmd(pfn, PAGE_S2); new_pmd = pmd_mkhuge(new_pmd); if (writable) { @@ -1069,6 +1081,23 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd); } else { pte_t new_pte = pfn_pte(pfn, PAGE_S2); + + /* + * If pmd is mapping a huge page then split it up into + * small pages, when doing live migration. + */ + if (migration_active) { + pmd_t *pmd; + if (hugetlb) { + pfn += pte_index(fault_ipa); + gfn = fault_ipa >> PAGE_SHIFT; + } + new_pte = pfn_pte(pfn, PAGE_S2); + pmd = stage2_get_pmd(kvm, NULL, fault_ipa); + if (pmd && kvm_pmd_huge(*pmd)) + clear_pmd_entry(kvm, pmd, fault_ipa); + } + if (writable) { kvm_set_s2pte_writable(&new_pte); kvm_set_pfn_dirty(pfn); @@ -1077,6 +1106,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, false); } + /* Assuming 4k pages, set one bit/page in memslot dirty_bitmap[] */ + if (writable) + mark_page_dirty(kvm, gfn); out_unlock: spin_unlock(&kvm->mmu_lock); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
