KVM: PPC: Book3S HV: Create kvmppc_unmap_hpte_helper()

The kvm_unmap_rmapp() function, called from certain MMU notifiers, is used
to force all guest mappings of a particular host page to be set ABSENT, and
removed from the reverse mappings.

For HPT resizing, we will have some cases where we want to set just a
single guest HPTE ABSENT and remove its reverse mappings.  To prepare with
this, we split out the logic from kvm_unmap_rmapp() to evict a single HPTE,
moving it to a new helper function.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 3a607fa..6d70989 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -742,13 +742,53 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
        return kvm_handle_hva_range(kvm, hva, hva + 1, handler);
 }
 
+/* Must be called with both HPTE and rmap locked */
+static void kvmppc_unmap_hpte(struct kvm *kvm, unsigned long i,
+                             unsigned long *rmapp, unsigned long gfn)
+{
+       __be64 *hptep = (__be64 *) (kvm->arch.hpt.virt + (i << 4));
+       struct revmap_entry *rev = kvm->arch.hpt.rev;
+       unsigned long j, h;
+       unsigned long ptel, psize, rcbits;
+
+       j = rev[i].forw;
+       if (j == i) {
+               /* chain is now empty */
+               *rmapp &= ~(KVMPPC_RMAP_PRESENT | KVMPPC_RMAP_INDEX);
+       } else {
+               /* remove i from chain */
+               h = rev[i].back;
+               rev[h].forw = j;
+               rev[j].back = h;
+               rev[i].forw = rev[i].back = i;
+               *rmapp = (*rmapp & ~KVMPPC_RMAP_INDEX) | j;
+       }
+
+       /* Now check and modify the HPTE */
+       ptel = rev[i].guest_rpte;
+       psize = hpte_page_size(be64_to_cpu(hptep[0]), ptel);
+       if ((be64_to_cpu(hptep[0]) & HPTE_V_VALID) &&
+           hpte_rpn(ptel, psize) == gfn) {
+               hptep[0] |= cpu_to_be64(HPTE_V_ABSENT);
+               kvmppc_invalidate_hpte(kvm, hptep, i);
+               hptep[1] &= ~cpu_to_be64(HPTE_R_KEY_HI | HPTE_R_KEY_LO);
+               /* Harvest R and C */
+               rcbits = be64_to_cpu(hptep[1]) & (HPTE_R_R | HPTE_R_C);
+               *rmapp |= rcbits << KVMPPC_RMAP_RC_SHIFT;
+               if (rcbits & HPTE_R_C)
+                       kvmppc_update_rmap_change(rmapp, psize);
+               if (rcbits & ~rev[i].guest_rpte) {
+                       rev[i].guest_rpte = ptel | rcbits;
+                       note_hpte_modification(kvm, &rev[i]);
+               }
+       }
+}
+
 static int kvm_unmap_rmapp(struct kvm *kvm, struct kvm_memory_slot *memslot,
                           unsigned long gfn)
 {
-       struct revmap_entry *rev = kvm->arch.hpt.rev;
-       unsigned long h, i, j;
+       unsigned long i;
        __be64 *hptep;
-       unsigned long ptel, psize, rcbits;
        unsigned long *rmapp;
 
        rmapp = &memslot->arch.rmap[gfn - memslot->base_gfn];
@@ -773,37 +813,8 @@ static int kvm_unmap_rmapp(struct kvm *kvm, struct kvm_memory_slot *memslot,
                                cpu_relax();
                        continue;
                }
-               j = rev[i].forw;
-               if (j == i) {
-                       /* chain is now empty */
-                       *rmapp &= ~(KVMPPC_RMAP_PRESENT | KVMPPC_RMAP_INDEX);
-               } else {
-                       /* remove i from chain */
-                       h = rev[i].back;
-                       rev[h].forw = j;
-                       rev[j].back = h;
-                       rev[i].forw = rev[i].back = i;
-                       *rmapp = (*rmapp & ~KVMPPC_RMAP_INDEX) | j;
-               }
 
-               /* Now check and modify the HPTE */
-               ptel = rev[i].guest_rpte;
-               psize = hpte_page_size(be64_to_cpu(hptep[0]), ptel);
-               if ((be64_to_cpu(hptep[0]) & HPTE_V_VALID) &&
-                   hpte_rpn(ptel, psize) == gfn) {
-                       hptep[0] |= cpu_to_be64(HPTE_V_ABSENT);
-                       kvmppc_invalidate_hpte(kvm, hptep, i);
-                       hptep[1] &= ~cpu_to_be64(HPTE_R_KEY_HI | HPTE_R_KEY_LO);
-                       /* Harvest R and C */
-                       rcbits = be64_to_cpu(hptep[1]) & (HPTE_R_R | HPTE_R_C);
-                       *rmapp |= rcbits << KVMPPC_RMAP_RC_SHIFT;
-                       if (rcbits & HPTE_R_C)
-                               kvmppc_update_rmap_change(rmapp, psize);
-                       if (rcbits & ~rev[i].guest_rpte) {
-                               rev[i].guest_rpte = ptel | rcbits;
-                               note_hpte_modification(kvm, &rev[i]);
-                       }
-               }
+               kvmppc_unmap_hpte(kvm, i, rmapp, gfn);
                unlock_rmap(rmapp);
                __unlock_hpte(hptep, be64_to_cpu(hptep[0]));
        }