RISC-V: Check PMP during Page Table Walks

The PMP should be checked when doing a page table walk, and report access
fault exception if the to-be-read PTE failed the PMP check.

Suggested-by: Jonathan Behrens <fintelia@gmail.com>
Signed-off-by: Hesham Almatary <Hesham.Almatary@cl.cam.ac.uk>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

target/riscv/cpu.h

@@ -81,6 +81,7 @@ enum {
 #define PRIV_VERSION_1_09_1 0x00010901
 #define PRIV_VERSION_1_10_0 0x00011000
 
+#define TRANSLATE_PMP_FAIL 2
 #define TRANSLATE_FAIL 1
 #define TRANSLATE_SUCCESS 0
 #define MMU_USER_IDX 3

target/riscv/cpu_helper.c

@@ -230,6 +230,12 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
 
         /* check that physical address of PTE is legal */
         target_ulong pte_addr = base + idx * ptesize;
+
+        if (riscv_feature(env, RISCV_FEATURE_PMP) &&
+            !pmp_hart_has_privs(env, pte_addr, sizeof(target_ulong),
+            1 << MMU_DATA_LOAD, PRV_S)) {
+            return TRANSLATE_PMP_FAIL;
+        }
 #if defined(TARGET_RISCV32)
         target_ulong pte = ldl_phys(cs->as, pte_addr);
 #elif defined(TARGET_RISCV64)
@@ -448,8 +454,10 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
         (ret == TRANSLATE_SUCCESS) &&
         !pmp_hart_has_privs(env, pa, TARGET_PAGE_SIZE, 1 << access_type,
         mode)) {
+        ret = TRANSLATE_PMP_FAIL;
+    }
+    if (ret == TRANSLATE_PMP_FAIL) {
         pmp_violation = true;
-        ret = TRANSLATE_FAIL;
     }
     if (ret == TRANSLATE_SUCCESS) {
         tlb_set_page(cs, address & TARGET_PAGE_MASK, pa & TARGET_PAGE_MASK,