KVM: PPC: Book3s HV: Implement get_dirty_log using hardware changed bit

[mv-sheeva.git] / arch / powerpc / kvm / book3s_64_mmu_hv.c

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 926e2b92bdabeb716562bb9375daaddf1080e392..783cd3510c93963deb03ff1a8e3ec91bebd6def4 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -870,6 +870,75 @@ void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
        kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
 }
 
+static int kvm_test_clear_dirty(struct kvm *kvm, unsigned long *rmapp)
+{
+       struct revmap_entry *rev = kvm->arch.revmap;
+       unsigned long head, i, j;
+       unsigned long *hptep;
+       int ret = 0;
+
+ retry:
+       lock_rmap(rmapp);
+       if (*rmapp & KVMPPC_RMAP_CHANGED) {
+               *rmapp &= ~KVMPPC_RMAP_CHANGED;
+               ret = 1;
+       }
+       if (!(*rmapp & KVMPPC_RMAP_PRESENT)) {
+               unlock_rmap(rmapp);
+               return ret;
+       }
+
+       i = head = *rmapp & KVMPPC_RMAP_INDEX;
+       do {
+               hptep = (unsigned long *) (kvm->arch.hpt_virt + (i << 4));
+               j = rev[i].forw;
+
+               if (!(hptep[1] & HPTE_R_C))
+                       continue;
+
+               if (!try_lock_hpte(hptep, HPTE_V_HVLOCK)) {
+                       /* unlock rmap before spinning on the HPTE lock */
+                       unlock_rmap(rmapp);
+                       while (hptep[0] & HPTE_V_HVLOCK)
+                               cpu_relax();
+                       goto retry;
+               }
+
+               /* Now check and modify the HPTE */
+               if ((hptep[0] & HPTE_V_VALID) && (hptep[1] & HPTE_R_C)) {
+                       /* need to make it temporarily absent to clear C */
+                       hptep[0] |= HPTE_V_ABSENT;
+                       kvmppc_invalidate_hpte(kvm, hptep, i);
+                       hptep[1] &= ~HPTE_R_C;
+                       eieio();
+                       hptep[0] = (hptep[0] & ~HPTE_V_ABSENT) | HPTE_V_VALID;
+                       rev[i].guest_rpte |= HPTE_R_C;
+                       ret = 1;
+               }
+               hptep[0] &= ~HPTE_V_HVLOCK;
+       } while ((i = j) != head);
+
+       unlock_rmap(rmapp);
+       return ret;
+}
+
+long kvmppc_hv_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+       unsigned long i;
+       unsigned long *rmapp, *map;
+
+       preempt_disable();
+       rmapp = memslot->rmap;
+       map = memslot->dirty_bitmap;
+       for (i = 0; i < memslot->npages; ++i) {
+               if (kvm_test_clear_dirty(kvm, rmapp))
+                       __set_bit_le(i, map);
+               ++rmapp;
+       }
+       preempt_enable();
+       return 0;
+}
+
 void *kvmppc_pin_guest_page(struct kvm *kvm, unsigned long gpa,
                            unsigned long *nb_ret)
 {