Virtual hash page table handling on pSeries machine

On pSeries logical partitions, excepting the old POWER4-style full system
partitions, the guest does not have direct access to the hardware page
table.  Instead, the pagetable exists in hypervisor memory, and the guest
must manipulate it with hypercalls.

However, our current pSeries emulation more closely resembles the old
style where the guest must set up and handle the pagetables itself.  This
patch converts it to act like a modern partition.

This involves two things: first, the hash translation path is modified to
permit the has table to be stored externally to the emulated machine's
RAM.  The pSeries machine init code configures the CPUs to use this mode.

Secondly, we emulate the PAPR hypercalls for manipulating the external
hashed page table.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

2 files changed, 30 insertions, 8 deletions

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 25d0658c4..b4c255562 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -670,6 +670,8 @@ struct CPUPPCState {
     target_phys_addr_t htab_base;
     target_phys_addr_t htab_mask;
     target_ulong sr[32];
+    /* externally stored hash table */
+    uint8_t *external_htab;
     /* BATs */
     int nb_BATs;
     target_ulong DBAT[2][8];
diff --git a/target-ppc/helper.c b/target-ppc/helper.c
index 278bee4f1..5e4030bb5 100644
--- a/target-ppc/helper.c
+++ b/target-ppc/helper.c
@@ -589,8 +589,13 @@ static inline int _find_pte(CPUState *env, mmu_ctx_t *ctx, int is_64b, int h,
     for (i = 0; i < 8; i++) {
 #if defined(TARGET_PPC64)
         if (is_64b) {
-            pte0 = ldq_phys(env->htab_base + pteg_off + (i * 16));
-            pte1 = ldq_phys(env->htab_base + pteg_off + (i * 16) + 8);
+            if (env->external_htab) {
+                pte0 = ldq_p(env->external_htab + pteg_off + (i * 16));
+                pte1 = ldq_p(env->external_htab + pteg_off + (i * 16) + 8);
+            } else {
+                pte0 = ldq_phys(env->htab_base + pteg_off + (i * 16));
+                pte1 = ldq_phys(env->htab_base + pteg_off + (i * 16) + 8);
+            }
 
             /* We have a TLB that saves 4K pages, so let's
              * split a huge page to 4k chunks */
@@ -606,8 +611,13 @@ static inline int _find_pte(CPUState *env, mmu_ctx_t *ctx, int is_64b, int h,
         } else
 #endif
         {
-            pte0 = ldl_phys(env->htab_base + pteg_off + (i * 8));
-            pte1 =  ldl_phys(env->htab_base + pteg_off + (i * 8) + 4);
+            if (env->external_htab) {
+                pte0 = ldl_p(env->external_htab + pteg_off + (i * 8));
+                pte1 = ldl_p(env->external_htab + pteg_off + (i * 8) + 4);
+            } else {
+                pte0 = ldl_phys(env->htab_base + pteg_off + (i * 8));
+                pte1 = ldl_phys(env->htab_base + pteg_off + (i * 8) + 4);
+            }
             r = pte32_check(ctx, pte0, pte1, h, rw, type);
             LOG_MMU("Load pte from " TARGET_FMT_lx " => " TARGET_FMT_lx " "
                     TARGET_FMT_lx " %d %d %d " TARGET_FMT_lx "\n",
@@ -647,13 +657,23 @@ static inline int _find_pte(CPUState *env, mmu_ctx_t *ctx, int is_64b, int h,
         if (pte_update_flags(ctx, &pte1, ret, rw) == 1) {
 #if defined(TARGET_PPC64)
             if (is_64b) {
-                stq_phys_notdirty(env->htab_base + pteg_off + (good * 16) + 8,
-                                  pte1);
+                if (env->external_htab) {
+                    stq_p(env->external_htab + pteg_off + (good * 16) + 8,
+                          pte1);
+                } else {
+                    stq_phys_notdirty(env->htab_base + pteg_off +
+                                      (good * 16) + 8, pte1);
+                }
             } else
 #endif
             {
-                stl_phys_notdirty(env->htab_base + pteg_off + (good * 8) + 4,
-                                  pte1);
+                if (env->external_htab) {
+                    stl_p(env->external_htab + pteg_off + (good * 8) + 4,
+                          pte1);
+                } else {
+                    stl_phys_notdirty(env->htab_base + pteg_off +
+                                      (good * 8) + 4, pte1);
+                }
             }
         }
     }