[Qemu-devel] [PATCH 08/27] Parse SDR1 on mtspr instead of at translate time

[David Gibson]

On ppc machines with hash table MMUs, the special purpose register SDR1
contains both the base address of the encoded size (hashed) page tables.

At present, we interpret the SDR1 value within the address translation
path.  But because the encodings of the size for 32-bit and 64-bit are
different this makes for a confusing branch on the MMU type with a bunch
of curly shifts and masks in the middle of the translate path.

This patch cleans things up by moving the interpretation on SDR1 into the
helper function handling the write to the register.  This leaves a simple
pre-sanitized base address and mask for the hash table in the CPUState
structure which is easier to work with in the translation path.

This makes the translation path more readable.  It addresses the FIXME
comment currently in the mtsdr1 helper, by validating the SDR1 value during
interpretation.  Finally it opens the way for emulating a pSeries-style
partition where the hash table used for translation is not mapped into
the guests's RAM.

Signed-off-by: David Gibson <address@hidden>
---
 monitor.c                   |    2 +-
 target-ppc/cpu.h            |   11 +++++-
 target-ppc/helper.c         |   80 ++++++++++++++++++++++++-------------------
 target-ppc/kvm.c            |    2 +-
 target-ppc/machine.c        |    6 ++-
 target-ppc/translate.c      |    2 +-
 target-ppc/translate_init.c |    7 +---
 7 files changed, 63 insertions(+), 47 deletions(-)

diff --git a/monitor.c b/monitor.c
index 76a8207..f1a08dc 100644
--- a/monitor.c
+++ b/monitor.c
@@ -3462,7 +3462,7 @@ static const MonitorDef monitor_defs[] = {
     { "asr", offsetof(CPUState, asr) },
 #endif
     /* Segment registers */
-    { "sdr1", offsetof(CPUState, sdr1) },
+    { "sdr1", offsetof(CPUState, spr[SPR_SDR1]) },
     { "sr0", offsetof(CPUState, sr[0]) },
     { "sr1", offsetof(CPUState, sr[1]) },
     { "sr2", offsetof(CPUState, sr[2]) },
diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 37dde39..ead4566 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -359,6 +359,14 @@ union ppc_tlb_t {
 };
 #endif
 
+#define SDR_32_HTABORG         0xFFFF0000UL
+#define SDR_32_HTABMASK        0x000001FFUL
+
+#if defined(TARGET_PPC64)
+#define SDR_64_HTABORG         0xFFFFFFFFFFFC0000ULL
+#define SDR_64_HTABSIZE        0x000000000000001FULL
+#endif /* defined(TARGET_PPC64 */
+
 typedef struct ppc_slb_t ppc_slb_t;
 struct ppc_slb_t {
     uint64_t esid;
@@ -642,7 +650,8 @@ struct CPUPPCState {
     int slb_nr;
 #endif
     /* segment registers */
-    target_ulong sdr1;
+    target_phys_addr_t htab_base;
+    target_phys_addr_t htab_mask;
     target_ulong sr[32];
     /* BATs */
     int nb_BATs;
diff --git a/target-ppc/helper.c b/target-ppc/helper.c
index 7ca33cb..68d2d9c 100644
--- a/target-ppc/helper.c
+++ b/target-ppc/helper.c
@@ -788,20 +788,19 @@ int ppc_load_slb_vsid (CPUPPCState *env, target_ulong rb, 
target_ulong *rt)
 #endif /* defined(TARGET_PPC64) */
 
 /* Perform segment based translation */
-static inline target_phys_addr_t get_pgaddr(target_phys_addr_t sdr1,
-                                            int sdr_sh,
-                                            target_phys_addr_t hash,
-                                            target_phys_addr_t mask)
+static inline target_phys_addr_t get_pgaddr(target_phys_addr_t htab_base,
+                                            target_phys_addr_t htab_mask,
+                                            target_phys_addr_t hash)
 {
-    return (sdr1 & ((target_phys_addr_t)(-1ULL) << sdr_sh)) | (hash & mask);
+    return htab_base | (hash & htab_mask);
 }
 
 static inline int get_segment(CPUState *env, mmu_ctx_t *ctx,
                               target_ulong eaddr, int rw, int type)
 {
-    target_phys_addr_t sdr, hash, mask, sdr_mask, htab_mask;
+    target_phys_addr_t hash;
     target_ulong sr, vsid, vsid_mask, pgidx, page_mask;
-    int ds, vsid_sh, sdr_sh, pr, target_page_bits;
+    int ds, vsid_sh, pr, target_page_bits;
     int ret, ret2;
 
     pr = msr_pr;
@@ -826,8 +825,6 @@ static inline int get_segment(CPUState *env, mmu_ctx_t *ctx,
         ctx->eaddr = eaddr;
         vsid_mask = 0x00003FFFFFFFFF80ULL;
         vsid_sh = 7;
-        sdr_sh = 18;
-        sdr_mask = 0x3FF80;
     } else
 #endif /* defined(TARGET_PPC64) */
     {
@@ -840,8 +837,6 @@ static inline int get_segment(CPUState *env, mmu_ctx_t *ctx,
         vsid = sr & 0x00FFFFFF;
         vsid_mask = 0x01FFFFC0;
         vsid_sh = 6;
-        sdr_sh = 16;
-        sdr_mask = 0xFFC0;
         target_page_bits = TARGET_PAGE_BITS;
         LOG_MMU("Check segment v=" TARGET_FMT_lx " %d " TARGET_FMT_lx " nip="
                 TARGET_FMT_lx " lr=" TARGET_FMT_lx
@@ -857,29 +852,26 @@ static inline int get_segment(CPUState *env, mmu_ctx_t 
*ctx,
         if (type != ACCESS_CODE || ctx->nx == 0) {
             /* Page address translation */
             /* Primary table address */
-            sdr = env->sdr1;
             pgidx = (eaddr & page_mask) >> target_page_bits;
 #if defined(TARGET_PPC64)
             if (env->mmu_model & POWERPC_MMU_64) {
-                htab_mask = 0x0FFFFFFF >> (28 - (sdr & 0x1F));
                 /* XXX: this is false for 1 TB segments */
                 hash = ((vsid ^ pgidx) << vsid_sh) & vsid_mask;
             } else
 #endif
             {
-                htab_mask = sdr & 0x000001FF;
                 hash = ((vsid ^ pgidx) << vsid_sh) & vsid_mask;
             }
-            mask = (htab_mask << sdr_sh) | sdr_mask;
-            LOG_MMU("sdr " TARGET_FMT_plx " sh %d hash " TARGET_FMT_plx
-                    " mask " TARGET_FMT_plx " " TARGET_FMT_lx "\n",
-                    sdr, sdr_sh, hash, mask, page_mask);
-            ctx->pg_addr[0] = get_pgaddr(sdr, sdr_sh, hash, mask);
+            LOG_MMU("htab_base " TARGET_FMT_plx " htab_mask " TARGET_FMT_plx
+                    " hash " TARGET_FMT_plx "\n",
+                    env->htab_base, env->htab_mask, hash);
+            ctx->pg_addr[0] = get_pgaddr(env->htab_base, env->htab_mask, hash);
             /* Secondary table address */
             hash = (~hash) & vsid_mask;
-            LOG_MMU("sdr " TARGET_FMT_plx " sh %d hash " TARGET_FMT_plx
-                    " mask " TARGET_FMT_plx "\n", sdr, sdr_sh, hash, mask);
-            ctx->pg_addr[1] = get_pgaddr(sdr, sdr_sh, hash, mask);
+            LOG_MMU("htab_base " TARGET_FMT_plx " htab_mask " TARGET_FMT_plx
+                    " hash " TARGET_FMT_plx "\n",
+                    env->htab_base, env->htab_mask, hash);
+            ctx->pg_addr[1] = get_pgaddr(env->htab_base, env->htab_mask, hash);
 #if defined(TARGET_PPC64)
             if (env->mmu_model & POWERPC_MMU_64) {
                 /* Only 5 bits of the page index are used in the AVPN */
@@ -901,19 +893,22 @@ static inline int get_segment(CPUState *env, mmu_ctx_t 
*ctx,
                 /* Software TLB search */
                 ret = ppc6xx_tlb_check(env, ctx, eaddr, rw, type);
             } else {
-                LOG_MMU("0 sdr1=" TARGET_FMT_plx " vsid=" TARGET_FMT_lx " "
-                        "api=" TARGET_FMT_lx " hash=" TARGET_FMT_plx
-                        " pg_addr=" TARGET_FMT_plx "\n",
-                        sdr, vsid, pgidx, hash, ctx->pg_addr[0]);
+                LOG_MMU("0 htab=" TARGET_FMT_plx "/" TARGET_FMT_plx
+                        " vsid=" TARGET_FMT_lx " api=" TARGET_FMT_lx
+                        " hash=" TARGET_FMT_plx " pg_addr=" TARGET_FMT_plx 
"\n",
+                        env->htab_base, env->htab_mask, vsid, pgidx, hash,
+                        ctx->pg_addr[0]);
                 /* Primary table lookup */
                 ret = find_pte(env, ctx, 0, rw, type, target_page_bits);
                 if (ret < 0) {
                     /* Secondary table lookup */
                     if (eaddr != 0xEFFFFFFF)
-                        LOG_MMU("1 sdr1=" TARGET_FMT_plx " vsid=" 
TARGET_FMT_lx " "
-                                "api=" TARGET_FMT_lx " hash=" TARGET_FMT_plx
-                                " pg_addr=" TARGET_FMT_plx "\n", sdr, vsid,
-                                pgidx, hash, ctx->pg_addr[1]);
+                        LOG_MMU("1 htab=" TARGET_FMT_plx "/" TARGET_FMT_plx
+                                " vsid=" TARGET_FMT_lx " api=" TARGET_FMT_lx
+                                " hash=" TARGET_FMT_plx " pg_addr="
+                                TARGET_FMT_plx "\n", env->htab_base,
+                                env->htab_mask, vsid, pgidx, hash,
+                                ctx->pg_addr[1]);
                     ret2 = find_pte(env, ctx, 1, rw, type,
                                     target_page_bits);
                     if (ret2 != -1)
@@ -1919,11 +1914,26 @@ void ppc_store_asr (CPUPPCState *env, target_ulong 
value)
 void ppc_store_sdr1 (CPUPPCState *env, target_ulong value)
 {
     LOG_MMU("%s: " TARGET_FMT_lx "\n", __func__, value);
-    if (env->sdr1 != value) {
-        /* XXX: for PowerPC 64, should check that the HTABSIZE value
-         *      is <= 28
-         */
-        env->sdr1 = value;
+    if (env->spr[SPR_SDR1] != value) {
+        env->spr[SPR_SDR1] = value;
+#if defined(TARGET_PPC64)
+        if (env->mmu_model & POWERPC_MMU_64) {
+            target_ulong htabsize = value & SDR_64_HTABSIZE;
+
+            if (htabsize > 28) {
+                fprintf(stderr, "Invalid HTABSIZE 0x" TARGET_FMT_lx
+                        " stored in SDR1\n", htabsize);
+                htabsize = 28;
+            }
+            env->htab_mask = (1ULL << (htabsize + 18)) - 1;
+            env->htab_base = value & SDR_64_HTABORG;
+        } else
+#endif /* defined(TARGET_PPC64) */
+        {
+            /* FIXME: Should check for valid HTABMASK values */
+            env->htab_mask = ((value & SDR_32_HTABMASK) << 16) | 0xFFFF;
+            env->htab_base = value & SDR_32_HTABORG;
+        }
         tlb_flush(env, 1);
     }
 }
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 0e2e67b..2cfb24b 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -169,7 +169,7 @@ int kvm_arch_get_registers(CPUState *env)
 
 #ifdef KVM_CAP_PPC_SEGSTATE
     if (kvm_check_extension(env->kvm_state, KVM_CAP_PPC_SEGSTATE)) {
-        env->sdr1 = sregs.u.s.sdr1;
+        ppc_store_sdr1(env, sregs.u.s.sdr1);
 
         /* Sync SLB */
 #ifdef TARGET_PPC64
diff --git a/target-ppc/machine.c b/target-ppc/machine.c
index 67de951..0c1986e 100644
--- a/target-ppc/machine.c
+++ b/target-ppc/machine.c
@@ -37,7 +37,7 @@ void cpu_save(QEMUFile *f, void *opaque)
     qemu_put_betls(f, &env->asr);
     qemu_put_sbe32s(f, &env->slb_nr);
 #endif
-    qemu_put_betls(f, &env->sdr1);
+    qemu_put_betls(f, &env->spr[SPR_SDR1]);
     for (i = 0; i < 32; i++)
         qemu_put_betls(f, &env->sr[i]);
     for (i = 0; i < 2; i++)
@@ -93,6 +93,7 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
 {
     CPUState *env = (CPUState *)opaque;
     unsigned int i, j;
+    target_ulong sdr1;
 
     for (i = 0; i < 32; i++)
         qemu_get_betls(f, &env->gpr[i]);
@@ -124,7 +125,7 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
     qemu_get_betls(f, &env->asr);
     qemu_get_sbe32s(f, &env->slb_nr);
 #endif
-    qemu_get_betls(f, &env->sdr1);
+    qemu_get_betls(f, &sdr1);
     for (i = 0; i < 32; i++)
         qemu_get_betls(f, &env->sr[i]);
     for (i = 0; i < 2; i++)
@@ -152,6 +153,7 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
 #endif
     for (i = 0; i < 1024; i++)
         qemu_get_betls(f, &env->spr[i]);
+    ppc_store_sdr1(env, sdr1);
     qemu_get_be32s(f, &env->vscr);
     qemu_get_be64s(f, &env->spe_acc);
     qemu_get_be32s(f, &env->spe_fscr);
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 0547047..b77f666 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -9126,7 +9126,7 @@ void cpu_dump_state (CPUState *env, FILE *f, 
fprintf_function cpu_fprintf,
 #if !defined(CONFIG_USER_ONLY)
     cpu_fprintf(f, "SRR0 " TARGET_FMT_lx " SRR1 " TARGET_FMT_lx " SDR1 "
                 TARGET_FMT_lx "\n", env->spr[SPR_SRR0], env->spr[SPR_SRR1],
-                env->sdr1);
+                env->spr[SPR_SDR1]);
 #endif
 
 #undef RGPL
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index f9ed0fa..695936b 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -341,11 +341,6 @@ static void spr_write_dbatl_h (void *opaque, int sprn, int 
gprn)
 }
 
 /* SDR1 */
-static void spr_read_sdr1 (void *opaque, int gprn, int sprn)
-{
-    tcg_gen_ld_tl(cpu_gpr[gprn], cpu_env, offsetof(CPUState, sdr1));
-}
-
 static void spr_write_sdr1 (void *opaque, int sprn, int gprn)
 {
     gen_helper_store_sdr1(cpu_gpr[gprn]);
@@ -669,7 +664,7 @@ static void gen_spr_ne_601 (CPUPPCState *env)
     /* Memory management */
     spr_register(env, SPR_SDR1, "SDR1",
                  SPR_NOACCESS, SPR_NOACCESS,
-                 &spr_read_sdr1, &spr_write_sdr1,
+                 &spr_read_generic, &spr_write_sdr1,
                  0x00000000);
 }
 
-- 
1.7.1