target/ppc: Cleanup HPTE accessors for 64-bit hash MMU

Accesses to the hashed page table (HPT) are complicated by the fact that
the HPT could be in one of three places:
   1) Within guest memory - when we're emulating a full guest CPU at the
      hardware level (e.g. powernv, mac99, g3beige)
   2) Within qemu, but outside guest memory - when we're emulating user and
      supervisor instructions within TCG, but instead of emulating
      the CPU's hypervisor mode, we just emulate a hypervisor's behaviour
      (pseries in TCG or KVM-PR)
   3) Within the host kernel - a pseries machine using KVM-HV
      acceleration.  Mostly accesses to the HPT are handled by KVM,
      but there are a few cases where qemu needs to access it via a
      special fd for the purpose.

In order to batch accesses to the fd in case (3), we use a somewhat awkward
ppc_hash64_start_access() / ppc_hash64_stop_access() pair, which for case
(3) reads / releases several HPTEs from the kernel as a batch (usually a
whole PTEG).  For cases (1) & (2) it just returns an address value.  The
actual HPTE load helpers then need to interpret the returned token
differently in the 3 cases.

This patch keeps the same basic structure, but simplfiies the details.
First start_access() / stop_access() are renamed to map_hptes() and
unmap_hptes() to make their operation more obvious.  Second, map_hptes()
now always returns a qemu pointer, which can always be used in the same way
by the load_hpte() helpers.  In case (1) it comes from address_space_map()
in case (2) directly from qemu's HPT buffer and in case (3) from a
temporary buffer read from the KVM fd.

While we're at it, make things a bit more consistent in terms of types and
variable names: avoid variables named 'index' (it shadows index(3) which
can lead to confusing results), use 'hwaddr ptex' for HPTE indices and
uint64_t for each of the HPTE words, use ptex throughout the call stack
instead of pte_offset in some places (we still need that at the bottom
layer, but nowhere else).

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 18 insertions, 18 deletions

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 3298a142c8..fd961b58d1 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -84,7 +84,7 @@ static target_ulong h_enter(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     unsigned apshift;
     target_ulong raddr;
     target_ulong slot;
-    uint64_t token;
+    const ppc_hash_pte64_t *hptes;
 
     apshift = ppc_hash64_hpte_page_shift_noslb(cpu, pteh, ptel);
     if (!apshift) {
@@ -123,23 +123,23 @@ static target_ulong h_enter(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     ptex = ptex & ~7ULL;
 
     if (likely((flags & H_EXACT) == 0)) {
-        token = ppc_hash64_start_access(cpu, ptex);
+        hptes = ppc_hash64_map_hptes(cpu, ptex, HPTES_PER_GROUP);
         for (slot = 0; slot < 8; slot++) {
-            if (!(ppc_hash64_load_hpte0(cpu, token, slot) & HPTE64_V_VALID)) {
+            if (!(ppc_hash64_hpte0(cpu, hptes, slot) & HPTE64_V_VALID)) {
                 break;
             }
         }
-        ppc_hash64_stop_access(cpu, token);
+        ppc_hash64_unmap_hptes(cpu, hptes, ptex, HPTES_PER_GROUP);
         if (slot == 8) {
             return H_PTEG_FULL;
         }
     } else {
-        token = ppc_hash64_start_access(cpu, ptex);
-        if (ppc_hash64_load_hpte0(cpu, token, 0) & HPTE64_V_VALID) {
-            ppc_hash64_stop_access(cpu, token);
+        hptes = ppc_hash64_map_hptes(cpu, ptex + slot, 1);
+        if (ppc_hash64_hpte0(cpu, hptes, 0) & HPTE64_V_VALID) {
+            ppc_hash64_unmap_hptes(cpu, hptes, ptex + slot, 1);
             return H_PTEG_FULL;
         }
-        ppc_hash64_stop_access(cpu, token);
+        ppc_hash64_unmap_hptes(cpu, hptes, ptex, 1);
     }
 
     ppc_hash64_store_hpte(cpu, ptex + slot, pteh | HPTE64_V_HPTE_DIRTY, ptel);
@@ -160,17 +160,17 @@ static RemoveResult remove_hpte(PowerPCCPU *cpu, target_ulong ptex,
                                 target_ulong flags,
                                 target_ulong *vp, target_ulong *rp)
 {
-    uint64_t token;
+    const ppc_hash_pte64_t *hptes;
     target_ulong v, r;
 
     if (!valid_ptex(cpu, ptex)) {
         return REMOVE_PARM;
     }
 
-    token = ppc_hash64_start_access(cpu, ptex);
-    v = ppc_hash64_load_hpte0(cpu, token, 0);
-    r = ppc_hash64_load_hpte1(cpu, token, 0);
-    ppc_hash64_stop_access(cpu, token);
+    hptes = ppc_hash64_map_hptes(cpu, ptex, 1);
+    v = ppc_hash64_hpte0(cpu, hptes, 0);
+    r = ppc_hash64_hpte1(cpu, hptes, 0);
+    ppc_hash64_unmap_hptes(cpu, hptes, ptex, 1);
 
     if ((v & HPTE64_V_VALID) == 0 ||
         ((flags & H_AVPN) && (v & ~0x7fULL) != avpn) ||
@@ -291,17 +291,17 @@ static target_ulong h_protect(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     target_ulong flags = args[0];
     target_ulong ptex = args[1];
     target_ulong avpn = args[2];
-    uint64_t token;
+    const ppc_hash_pte64_t *hptes;
     target_ulong v, r;
 
     if (!valid_ptex(cpu, ptex)) {
         return H_PARAMETER;
     }
 
-    token = ppc_hash64_start_access(cpu, ptex);
-    v = ppc_hash64_load_hpte0(cpu, token, 0);
-    r = ppc_hash64_load_hpte1(cpu, token, 0);
-    ppc_hash64_stop_access(cpu, token);
+    hptes = ppc_hash64_map_hptes(cpu, ptex, 1);
+    v = ppc_hash64_hpte0(cpu, hptes, 0);
+    r = ppc_hash64_hpte1(cpu, hptes, 0);
+    ppc_hash64_unmap_hptes(cpu, hptes, ptex, 1);
 
     if ((v & HPTE64_V_VALID) == 0 ||
         ((flags & H_AVPN) && (v & ~0x7fULL) != avpn)) {