To reduce MMU lock contention during dirty logging, all permission
relaxation operations would be performed under read lock.
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220118015703.3630552-3-jingzhangos@google.com
gfn_t gfn;
kvm_pfn_t pfn;
bool logging_active = memslot_is_logging(memslot);
gfn_t gfn;
kvm_pfn_t pfn;
bool logging_active = memslot_is_logging(memslot);
+ bool logging_perm_fault = false;
unsigned long fault_level = kvm_vcpu_trap_get_fault_level(vcpu);
unsigned long vma_pagesize, fault_granule;
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
unsigned long fault_level = kvm_vcpu_trap_get_fault_level(vcpu);
unsigned long vma_pagesize, fault_granule;
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
if (logging_active) {
force_pte = true;
vma_shift = PAGE_SHIFT;
if (logging_active) {
force_pte = true;
vma_shift = PAGE_SHIFT;
+ logging_perm_fault = (fault_status == FSC_PERM && write_fault);
} else {
vma_shift = get_vma_page_shift(vma, hva);
}
} else {
vma_shift = get_vma_page_shift(vma, hva);
}
if (exec_fault && device)
return -ENOEXEC;
if (exec_fault && device)
return -ENOEXEC;
- write_lock(&kvm->mmu_lock);
+ /*
+ * To reduce MMU contentions and enhance concurrency during dirty
+ * logging dirty logging, only acquire read lock for permission
+ * relaxation.
+ */
+ if (logging_perm_fault)
+ read_lock(&kvm->mmu_lock);
+ else
+ write_lock(&kvm->mmu_lock);
pgt = vcpu->arch.hw_mmu->pgt;
if (mmu_notifier_retry(kvm, mmu_seq))
goto out_unlock;
pgt = vcpu->arch.hw_mmu->pgt;
if (mmu_notifier_retry(kvm, mmu_seq))
goto out_unlock;
- write_unlock(&kvm->mmu_lock);
+ if (logging_perm_fault)
+ read_unlock(&kvm->mmu_lock);
+ else
+ write_unlock(&kvm->mmu_lock);
kvm_set_pfn_accessed(pfn);
kvm_release_pfn_clean(pfn);
return ret != -EAGAIN ? ret : 0;
kvm_set_pfn_accessed(pfn);
kvm_release_pfn_clean(pfn);
return ret != -EAGAIN ? ret : 0;