target/riscv: Ignore reserved bits in PTE for RV64

Highest bits of PTE has been used for svpbmt, ref: [1], [2], so we
need to ignore them. They cannot be a part of ppn.

1: The RISC-V Instruction Set Manual, Volume II: Privileged Architecture
   4.4 Sv39: Page-Based 39-bit Virtual-Memory System
   4.5 Sv48: Page-Based 48-bit Virtual-Memory System

2: https://github.com/riscv/virtual-memory/blob/main/specs/663-Svpbmt-diff.pdf



Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Liu Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Cc: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220204022658.18097-2-liweiwei@iscas.ac.cn>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.h

@@ -359,6 +359,8 @@ struct RISCVCPUConfig {
     bool ext_counters;
     bool ext_ifencei;
     bool ext_icsr;
+    bool ext_svnapot;
+    bool ext_svpbmt;
     bool ext_zfh;
     bool ext_zfhmin;
     bool ext_zve32f;
@@ -558,6 +560,19 @@ static inline int riscv_cpu_xlen(CPURISCVState *env)
     return 16 << env->xl;
 }
 
+#ifdef TARGET_RISCV32
+#define riscv_cpu_sxl(env)  ((void)(env), MXL_RV32)
+#else
+static inline RISCVMXL riscv_cpu_sxl(CPURISCVState *env)
+{
+#ifdef CONFIG_USER_ONLY
+    return env->misa_mxl;
+#else
+    return get_field(env->mstatus, MSTATUS64_SXL);
+#endif
+}
+#endif
+
 /*
  * Encode LMUL to lmul as follows:
  *     LMUL    vlmul    lmul

target/riscv/cpu_bits.h

@@ -565,6 +565,9 @@ typedef enum {
 /* Page table PPN shift amount */
 #define PTE_PPN_SHIFT       10
 
+/* Page table PPN mask */
+#define PTE_PPN_MASK        0x3FFFFFFFFFFC00ULL
+
 /* Leaf page shift amount */
 #define PGSHIFT             12
 

target/riscv/cpu_helper.c

@@ -751,6 +751,8 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
     MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
     int mode = mmu_idx & TB_FLAGS_PRIV_MMU_MASK;
     bool use_background = false;
+    hwaddr ppn;
+    RISCVCPU *cpu = env_archcpu(env);
 
     /*
      * Check if we should use the background registers for the two
@@ -919,7 +921,16 @@ restart:
             return TRANSLATE_FAIL;
         }
 
-        hwaddr ppn = pte >> PTE_PPN_SHIFT;
+        if (riscv_cpu_sxl(env) == MXL_RV32) {
+            ppn = pte >> PTE_PPN_SHIFT;
+        } else if (cpu->cfg.ext_svpbmt || cpu->cfg.ext_svnapot) {
+            ppn = (pte & (target_ulong)PTE_PPN_MASK) >> PTE_PPN_SHIFT;
+        } else {
+            ppn = pte >> PTE_PPN_SHIFT;
+            if ((pte & ~(target_ulong)PTE_PPN_MASK) >> PTE_PPN_SHIFT) {
+                return TRANSLATE_FAIL;
+            }
+        }
 
         if (!(pte & PTE_V)) {
             /* Invalid PTE */