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, 16 insertions, 30 deletions

diff --git a/target/ppc/mmu-hash64.h b/target/ppc/mmu-hash64.h
index 73aeaa3b64..edd687bcf8 100644
--- a/target/ppc/mmu-hash64.h
+++ b/target/ppc/mmu-hash64.h
@@ -10,8 +10,8 @@ int ppc_store_slb(PowerPCCPU *cpu, target_ulong slot,
 hwaddr ppc_hash64_get_phys_page_debug(PowerPCCPU *cpu, target_ulong addr);
 int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr address, int rw,
                                 int mmu_idx);
-void ppc_hash64_store_hpte(PowerPCCPU *cpu, target_ulong index,
-                           target_ulong pte0, target_ulong pte1);
+void ppc_hash64_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
+                           uint64_t pte0, uint64_t pte1);
 void ppc_hash64_tlb_flush_hpte(PowerPCCPU *cpu,
                                target_ulong pte_index,
                                target_ulong pte0, target_ulong pte1);
@@ -96,41 +96,27 @@ void ppc_hash64_set_sdr1(PowerPCCPU *cpu, target_ulong value,
 void ppc_hash64_set_external_hpt(PowerPCCPU *cpu, void *hpt, int shift,
                                  Error **errp);
 
-uint64_t ppc_hash64_start_access(PowerPCCPU *cpu, target_ulong pte_index);
-void ppc_hash64_stop_access(PowerPCCPU *cpu, uint64_t token);
+struct ppc_hash_pte64 {
+    uint64_t pte0, pte1;
+};
+
+const ppc_hash_pte64_t *ppc_hash64_map_hptes(PowerPCCPU *cpu,
+                                             hwaddr ptex, int n);
+void ppc_hash64_unmap_hptes(PowerPCCPU *cpu, const ppc_hash_pte64_t *hptes,
+                            hwaddr ptex, int n);
 
-static inline target_ulong ppc_hash64_load_hpte0(PowerPCCPU *cpu,
-                                                 uint64_t token, int index)
+static inline uint64_t ppc_hash64_hpte0(PowerPCCPU *cpu,
+                                        const ppc_hash_pte64_t *hptes, int i)
 {
-    CPUPPCState *env = &cpu->env;
-    uint64_t addr;
-
-    addr = token + (index * HASH_PTE_SIZE_64);
-    if (env->external_htab) {
-        return  ldq_p((const void *)(uintptr_t)addr);
-    } else {
-        return ldq_phys(CPU(cpu)->as, addr);
-    }
+    return ldq_p(&(hptes[i].pte0));
 }
 
-static inline target_ulong ppc_hash64_load_hpte1(PowerPCCPU *cpu,
-                                                 uint64_t token, int index)
+static inline uint64_t ppc_hash64_hpte1(PowerPCCPU *cpu,
+                                        const ppc_hash_pte64_t *hptes, int i)
 {
-    CPUPPCState *env = &cpu->env;
-    uint64_t addr;
-
-    addr = token + (index * HASH_PTE_SIZE_64) + HASH_PTE_SIZE_64/2;
-    if (env->external_htab) {
-        return  ldq_p((const void *)(uintptr_t)addr);
-    } else {
-        return ldq_phys(CPU(cpu)->as, addr);
-    }
+    return ldq_p(&(hptes[i].pte1));
 }
 
-typedef struct ppc_hash_pte64 {
-    uint64_t pte0, pte1;
-} ppc_hash_pte64_t;
-
 #endif /* CONFIG_USER_ONLY */
 
 #endif /* MMU_HASH64_H */