[PULL 32/39] target/riscv: Check memory access to meet svukte rule

[Alistair Francis]

From: "Fea.Wang" <fea.wang@sifive.com>

Follow the Svukte spec, do the memory access address checking

1. Include instruction fetches or explicit memory accesses
2. System run in effective privilege U or VU
3. Check senvcfg[UKTE] being set, or hstatus[HUKTE] being set if
instruction is HLV, HLVX, HSV and execute from U mode to VU mode
4. Depend on Sv39 and check virtual addresses bit[SXLEN-1]
5. Raises a page-fault exception corresponding to the original access
type.

Ref: https://github.com/riscv/riscv-isa-manual/pull/1564/files

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Signed-off-by: Fea.Wang <fea.wang@sifive.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Jim Shu <jim.shu@sifive.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241203034932.25185-5-fea.wang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/cpu_helper.c | 55 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 45806f5ab0..750c0537ca 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -857,6 +857,55 @@ static int get_physical_address_pmp(CPURISCVState *env, 
int *prot, hwaddr addr,
     return TRANSLATE_SUCCESS;
 }
 
+/* Returns 'true' if a svukte address check is needed */
+static bool do_svukte_check(CPURISCVState *env, bool first_stage,
+                             int mode, bool virt)
+{
+    /* Svukte extension depends on Sv39. */
+    if (!(env_archcpu(env)->cfg.ext_svukte ||
+        !first_stage ||
+        VM_1_10_SV39 != get_field(env->satp, SATP64_MODE))) {
+        return false;
+    }
+
+    /*
+     * Check hstatus.HUKTE if the effective mode is switched to VU-mode by
+     * executing HLV/HLVX/HSV in U-mode.
+     * For other cases, check senvcfg.UKTE.
+     */
+    if (env->priv == PRV_U && !env->virt_enabled && virt) {
+        if (!get_field(env->hstatus, HSTATUS_HUKTE)) {
+            return false;
+        }
+    } else if (!get_field(env->senvcfg, SENVCFG_UKTE)) {
+        return false;
+    }
+
+    /*
+     * Svukte extension is qualified only in U or VU-mode.
+     *
+     * Effective mode can be switched to U or VU-mode by:
+     *   - M-mode + mstatus.MPRV=1 + mstatus.MPP=U-mode.
+     *   - Execute HLV/HLVX/HSV from HS-mode + hstatus.SPVP=0.
+     *   - U-mode.
+     *   - VU-mode.
+     *   - Execute HLV/HLVX/HSV from U-mode + hstatus.HU=1.
+     */
+    if (mode != PRV_U) {
+        return false;
+    }
+
+    return true;
+}
+
+static bool check_svukte_addr(CPURISCVState *env, vaddr addr)
+{
+    /* svukte extension excludes RV32 */
+    uint32_t sxlen = 32 * riscv_cpu_sxl(env);
+    uint64_t high_bit = addr & (1UL << (sxlen - 1));
+    return !high_bit;
+}
+
 /*
  * get_physical_address - get the physical address for this virtual address
  *
@@ -894,6 +943,7 @@ static int get_physical_address(CPURISCVState *env, hwaddr 
*physical,
     MemTxResult res;
     MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
     int mode = mmuidx_priv(mmu_idx);
+    bool virt = mmuidx_2stage(mmu_idx);
     bool use_background = false;
     hwaddr ppn;
     int napot_bits = 0;
@@ -901,6 +951,11 @@ static int get_physical_address(CPURISCVState *env, hwaddr 
*physical,
     bool is_sstack_idx = ((mmu_idx & MMU_IDX_SS_WRITE) == MMU_IDX_SS_WRITE);
     bool sstack_page = false;
 
+    if (do_svukte_check(env, first_stage, mode, virt) &&
+        !check_svukte_addr(env, addr)) {
+        return TRANSLATE_FAIL;
+    }
+
     /*
      * Check if we should use the background registers for the two
      * stage translation. We don't need to check if we actually need
-- 
2.47.1