[Qemu-devel] [PATCH 2/2] ppc: Fix 64K pages support in full emulation

["Cédric Le Goater" <clg@kaod.org>]

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We were always advertising only 4K & 16M. Additionally the code wasn't
properly matching the page size with the PTE content, which meant we
could potentially hit an incorrect PTE if the guest used multiple sizes.

Finally, honor the CPU capabilities when decoding the size from the SLB
so we don't try to use 64K pages on 970.

This still doesn't add support for MPSS (Multiple Page Sizes per Segment)

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[clg: fixed checkpatch.pl errors
      commits 61a36c9b5a12 and 1114e712c998 reworked the hpte code
      doing insertion/removal in hw/ppc/spapr_hcall.c. The hunks
      modifying these areas were removed. ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 target-ppc/cpu-qom.h        |  3 +++
 target-ppc/mmu-hash64.c     | 39 +++++++++++++++++++++++++++++++++++----
 target-ppc/translate_init.c | 22 +++++++++++++++++++---
 3 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
index 0fad2def0a94..286410502f6d 100644
--- a/target-ppc/cpu-qom.h
+++ b/target-ppc/cpu-qom.h
@@ -70,18 +70,21 @@ enum powerpc_mmu_t {
 #define POWERPC_MMU_64       0x00010000
 #define POWERPC_MMU_1TSEG    0x00020000
 #define POWERPC_MMU_AMR      0x00040000
+#define POWERPC_MMU_64K      0x00080000
     /* 64 bits PowerPC MMU                                     */
     POWERPC_MMU_64B        = POWERPC_MMU_64 | 0x00000001,
     /* Architecture 2.03 and later (has LPCR) */
     POWERPC_MMU_2_03       = POWERPC_MMU_64 | 0x00000002,
     /* Architecture 2.06 variant                               */
     POWERPC_MMU_2_06       = POWERPC_MMU_64 | POWERPC_MMU_1TSEG
+                             | POWERPC_MMU_64K
                              | POWERPC_MMU_AMR | 0x00000003,
     /* Architecture 2.06 "degraded" (no 1T segments)           */
     POWERPC_MMU_2_06a      = POWERPC_MMU_64 | POWERPC_MMU_AMR
                              | 0x00000003,
     /* Architecture 2.07 variant                               */
     POWERPC_MMU_2_07       = POWERPC_MMU_64 | POWERPC_MMU_1TSEG
+                             | POWERPC_MMU_64K
                              | POWERPC_MMU_AMR | 0x00000004,
     /* Architecture 2.07 "degraded" (no 1T segments)           */
     POWERPC_MMU_2_07a      = POWERPC_MMU_64 | POWERPC_MMU_AMR
diff --git a/target-ppc/mmu-hash64.c b/target-ppc/mmu-hash64.c
index ed353b2d1539..fa26ad2e875b 100644
--- a/target-ppc/mmu-hash64.c
+++ b/target-ppc/mmu-hash64.c
@@ -450,9 +450,31 @@ void ppc_hash64_stop_access(PowerPCCPU *cpu, uint64_t token)
     }
 }
 
+/* Returns the effective page shift or 0. MPSS isn't supported yet so
+ * this will always be the slb_pshift or 0
+ */
+static uint32_t ppc_hash64_pte_size_decode(uint64_t pte1, uint32_t slb_pshift)
+{
+    switch (slb_pshift) {
+    case 12:
+        return 12;
+    case 16:
+        if ((pte1 & 0xf000) == 0x1000) {
+            return 16;
+        }
+        return 0;
+    case 24:
+        if ((pte1 & 0xff000) == 0) {
+            return 24;
+        }
+        return 0;
+    }
+    return 0;
+}
+
 static hwaddr ppc_hash64_pteg_search(PowerPCCPU *cpu, hwaddr hash,
-                                     bool secondary, target_ulong ptem,
-                                     ppc_hash_pte64_t *pte)
+                                     uint32_t slb_pshift, bool secondary,
+                                     target_ulong ptem, ppc_hash_pte64_t *pte)
 {
     CPUPPCState *env = &cpu->env;
     int i;
@@ -472,6 +494,13 @@ static hwaddr ppc_hash64_pteg_search(PowerPCCPU *cpu, hwaddr hash,
         if ((pte0 & HPTE64_V_VALID)
             && (secondary == !!(pte0 & HPTE64_V_SECONDARY))
             && HPTE64_V_COMPARE(pte0, ptem)) {
+            uint32_t pshift = ppc_hash64_pte_size_decode(pte1, slb_pshift);
+            if (pshift == 0) {
+                continue;
+            }
+            /* We don't do anything with pshift yet as qemu TLB only deals
+             * with 4K pages anyway
+             */
             pte->pte0 = pte0;
             pte->pte1 = pte1;
             ppc_hash64_stop_access(cpu, token);
@@ -525,7 +554,8 @@ static hwaddr ppc_hash64_htab_lookup(PowerPCCPU *cpu,
             " vsid=" TARGET_FMT_lx " ptem=" TARGET_FMT_lx
             " hash=" TARGET_FMT_plx "\n",
             env->htab_base, env->htab_mask, vsid, ptem,  hash);
-    pte_offset = ppc_hash64_pteg_search(cpu, hash, 0, ptem, pte);
+    pte_offset = ppc_hash64_pteg_search(cpu, hash, slb->sps->page_shift,
+                                        0, ptem, pte);
 
     if (pte_offset == -1) {
         /* Secondary PTEG lookup */
@@ -535,7 +565,8 @@ static hwaddr ppc_hash64_htab_lookup(PowerPCCPU *cpu,
                 " hash=" TARGET_FMT_plx "\n", env->htab_base,
                 env->htab_mask, vsid, ptem, ~hash);
 
-        pte_offset = ppc_hash64_pteg_search(cpu, ~hash, 1, ptem, pte);
+        pte_offset = ppc_hash64_pteg_search(cpu, ~hash, slb->sps->page_shift, 1,
+                                            ptem, pte);
     }
 
     return pte_offset;
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index 4820c0bc99fb..d7860fd7f8ee 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -10301,8 +10301,8 @@ static void ppc_cpu_initfn(Object *obj)
     if (pcc->sps) {
         env->sps = *pcc->sps;
     } else if (env->mmu_model & POWERPC_MMU_64) {
-        /* Use default sets of page sizes */
-        static const struct ppc_segment_page_sizes defsps = {
+        /* Use default sets of page sizes. We don't support MPSS */
+        static const struct ppc_segment_page_sizes defsps_4k = {
             .sps = {
                 { .page_shift = 12, /* 4K */
                   .slb_enc = 0,
@@ -10314,7 +10314,23 @@ static void ppc_cpu_initfn(Object *obj)
                 },
             },
         };
-        env->sps = defsps;
+        static const struct ppc_segment_page_sizes defsps_64k = {
+            .sps = {
+                { .page_shift = 12, /* 4K */
+                  .slb_enc = 0,
+                  .enc = { { .page_shift = 12, .pte_enc = 0 } }
+                },
+                { .page_shift = 16, /* 64K */
+                  .slb_enc = 0x110,
+                  .enc = { { .page_shift = 16, .pte_enc = 1 } }
+                },
+                { .page_shift = 24, /* 16M */
+                  .slb_enc = 0x100,
+                  .enc = { { .page_shift = 24, .pte_enc = 0 } }
+                },
+            },
+        };
+        env->sps = (env->mmu_model & POWERPC_MMU_64K) ? defsps_64k : defsps_4k;
     }
 #endif /* defined(TARGET_PPC64) */
 
-- 
2.1.4