[PATCH v6 1/5] target/riscv: Ignore reserved bits in PTE for RV64

[Weiwei Li]

From: Guo Ren <ren_guo@c-sky.com>

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>
Cc: Liu Zhiwei <zhiwei_liu@c-sky.com>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/cpu.h        | 13 +++++++++++++
 target/riscv/cpu_bits.h   |  7 +++++++
 target/riscv/cpu_helper.c | 14 +++++++++++++-
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 55635d68d5..45de8faaca 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -341,6 +341,8 @@ struct RISCVCPU {
         bool ext_counters;
         bool ext_ifencei;
         bool ext_icsr;
+        bool ext_svnapot;
+        bool ext_svpbmt;
         bool ext_zfh;
         bool ext_zfhmin;
         bool ext_zve32f;
@@ -495,6 +497,17 @@ static inline int riscv_cpu_xlen(CPURISCVState *env)
     return 16 << env->xl;
 }
 
+#ifndef CONFIG_USER_ONLY
+#ifdef TARGET_RISCV32
+#define riscv_cpu_sxl(env)  ((void)(env), MXL_RV32)
+#else
+static inline RISCVMXL riscv_cpu_sxl(CPURISCVState *env)
+{
+    return get_field(env->mstatus, MSTATUS64_SXL);
+}
+#endif
+#endif
+
 /*
  * Encode LMUL to lmul as follows:
  *     LMUL    vlmul    lmul
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 7c87433645..37b622fbfa 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -493,6 +493,13 @@ typedef enum {
 /* Page table PPN shift amount */
 #define PTE_PPN_SHIFT       10
 
+/* Page table PPN mask */
+#if defined(TARGET_RISCV32)
+#define PTE_PPN_MASK        0xFFFFFC00UL
+#elif defined(TARGET_RISCV64)
+#define PTE_PPN_MASK        0x3FFFFFFFFFFC00ULL
+#endif
+
 /* Leaf page shift amount */
 #define PGSHIFT             12
 
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 327a2c4f1d..2a921bedfd 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -622,7 +622,19 @@ restart:
             return TRANSLATE_FAIL;
         }
 
-        hwaddr ppn = pte >> PTE_PPN_SHIFT;
+        hwaddr ppn;
+        RISCVCPU *cpu = env_archcpu(env);
+
+        if (riscv_cpu_sxl(env) == MXL_RV32) {
+            ppn = pte >> PTE_PPN_SHIFT;
+        } else if (cpu->cfg.ext_svpbmt || cpu->cfg.ext_svnapot) {
+            ppn = (pte & PTE_PPN_MASK) >> PTE_PPN_SHIFT;
+        } else {
+            ppn = pte >> PTE_PPN_SHIFT;
+            if ((pte & ~PTE_PPN_MASK) >> PTE_PPN_SHIFT) {
+                return TRANSLATE_FAIL;
+            }
+        }
 
         if (!(pte & PTE_V)) {
             /* Invalid PTE */
-- 
2.17.1