target/riscv: Implement second stage MMU

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

target/riscv/cpu.h

@@ -104,6 +104,7 @@ struct CPURISCVState {
     target_ulong frm;
 
     target_ulong badaddr;
+    target_ulong guest_phys_fault_addr;
 
     target_ulong priv_ver;
     target_ulong misa;

target/riscv/cpu_helper.c

@@ -285,11 +285,12 @@ void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv)
  * @mmu_idx: Indicates current privilege level
  * @first_stage: Are we in first stage translation?
  *               Second stage is used for hypervisor guest translation
+ * @two_stage: Are we going to perform two stage translation
  */
 static int get_physical_address(CPURISCVState *env, hwaddr *physical,
                                 int *prot, target_ulong addr,
                                 int access_type, int mmu_idx,
-                                bool first_stage)
+                                bool first_stage, bool two_stage)
 {
     /* NOTE: the env->pc value visible here will not be
      * correct, but the value visible to the exception handler
@@ -297,13 +298,40 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
     MemTxResult res;
     MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
     int mode = mmu_idx;
+    bool use_background = false;
 
+    /*
+     * Check if we should use the background registers for the two
+     * stage translation. We don't need to check if we actually need
+     * two stage translation as that happened before this function
+     * was called. Background registers will be used if the guest has
+     * forced a two stage translation to be on (in HS or M mode).
+     */
     if (mode == PRV_M && access_type != MMU_INST_FETCH) {
         if (get_field(env->mstatus, MSTATUS_MPRV)) {
             mode = get_field(env->mstatus, MSTATUS_MPP);
+
+            if (riscv_has_ext(env, RVH) &&
+                get_field(env->mstatus, MSTATUS_MPV)) {
+                use_background = true;
+            }
         }
     }
 
+    if (mode == PRV_S && access_type != MMU_INST_FETCH &&
+        riscv_has_ext(env, RVH) && !riscv_cpu_virt_enabled(env)) {
+        if (get_field(env->hstatus, HSTATUS_SPRV)) {
+            mode = get_field(env->mstatus, SSTATUS_SPP);
+            use_background = true;
+        }
+    }
+
+    if (first_stage == false) {
+        /* We are in stage 2 translation, this is similar to stage 1. */
+        /* Stage 2 is always taken as U-mode */
+        mode = PRV_U;
+    }
+
     if (mode == PRV_M || !riscv_feature(env, RISCV_FEATURE_MMU)) {
         *physical = addr;
         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
@@ -313,13 +341,30 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
     *prot = 0;
 
     hwaddr base;
-    int levels, ptidxbits, ptesize, vm, sum;
+    int levels, ptidxbits, ptesize, vm, sum, mxr, widened;
-    int mxr = get_field(env->mstatus, MSTATUS_MXR);
+
+    if (first_stage == true) {
+        mxr = get_field(env->mstatus, MSTATUS_MXR);
+    } else {
+        mxr = get_field(env->vsstatus, MSTATUS_MXR);
+    }
 
     if (env->priv_ver >= PRIV_VERSION_1_10_0) {
-        base = (hwaddr)get_field(env->satp, SATP_PPN) << PGSHIFT;
+        if (first_stage == true) {
+            if (use_background) {
+                base = (hwaddr)get_field(env->vsatp, SATP_PPN) << PGSHIFT;
+                vm = get_field(env->vsatp, SATP_MODE);
+            } else {
+                base = (hwaddr)get_field(env->satp, SATP_PPN) << PGSHIFT;
+                vm = get_field(env->satp, SATP_MODE);
+            }
+            widened = 0;
+        } else {
+            base = (hwaddr)get_field(env->hgatp, HGATP_PPN) << PGSHIFT;
+            vm = get_field(env->hgatp, HGATP_MODE);
+            widened = 2;
+        }
         sum = get_field(env->mstatus, MSTATUS_SUM);
-        vm = get_field(env->satp, SATP_MODE);
         switch (vm) {
         case VM_1_10_SV32:
           levels = 2; ptidxbits = 10; ptesize = 4; break;
@@ -337,6 +382,7 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
           g_assert_not_reached();
         }
     } else {
+        widened = 0;
         base = (hwaddr)(env->sptbr) << PGSHIFT;
         sum = !get_field(env->mstatus, MSTATUS_PUM);
         vm = get_field(env->mstatus, MSTATUS_VM);
@@ -357,9 +403,16 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
     }
 
     CPUState *cs = env_cpu(env);
-    int va_bits = PGSHIFT + levels * ptidxbits;
+    int va_bits = PGSHIFT + levels * ptidxbits + widened;
-    target_ulong mask = (1L << (TARGET_LONG_BITS - (va_bits - 1))) - 1;
+    target_ulong mask, masked_msbs;
-    target_ulong masked_msbs = (addr >> (va_bits - 1)) & mask;
+
+    if (TARGET_LONG_BITS > (va_bits - 1)) {
+        mask = (1L << (TARGET_LONG_BITS - (va_bits - 1))) - 1;
+    } else {
+        mask = 0;
+    }
+    masked_msbs = (addr >> (va_bits - 1)) & mask;
+
     if (masked_msbs != 0 && masked_msbs != mask) {
         return TRANSLATE_FAIL;
     }
@@ -371,11 +424,29 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
 restart:
 #endif
     for (i = 0; i < levels; i++, ptshift -= ptidxbits) {
-        target_ulong idx = (addr >> (PGSHIFT + ptshift)) &
+        target_ulong idx;
+        if (i == 0) {
+            idx = (addr >> (PGSHIFT + ptshift)) &
+                           ((1 << (ptidxbits + widened)) - 1);
+        } else {
+            idx = (addr >> (PGSHIFT + ptshift)) &
                            ((1 << ptidxbits) - 1);
+        }
 
         /* check that physical address of PTE is legal */
-        hwaddr pte_addr = base + idx * ptesize;
+        hwaddr pte_addr;
+
+        if (two_stage && first_stage) {
+            hwaddr vbase;
+
+            /* Do the second stage translation on the base PTE address. */
+            get_physical_address(env, &vbase, prot, base, access_type,
+                                 mmu_idx, false, true);
+
+            pte_addr = vbase + idx * ptesize;
+        } else {
+            pte_addr = base + idx * ptesize;
+        }
 
         if (riscv_feature(env, RISCV_FEATURE_PMP) &&
             !pmp_hart_has_privs(env, pte_addr, sizeof(target_ulong),
@@ -472,7 +543,12 @@ restart:
             /* for superpage mappings, make a fake leaf PTE for the TLB's
                benefit. */
             target_ulong vpn = addr >> PGSHIFT;
-            *physical = (ppn | (vpn & ((1L << ptshift) - 1))) << PGSHIFT;
+            if (i == 0) {
+                *physical = (ppn | (vpn & ((1L << (ptshift + widened)) - 1))) <<
+                             PGSHIFT;
+            } else {
+                *physical = (ppn | (vpn & ((1L << ptshift) - 1))) << PGSHIFT;
+            }
 
             /* set permissions on the TLB entry */
             if ((pte & PTE_R) || ((pte & PTE_X) && mxr)) {
@@ -531,14 +607,23 @@ static void raise_mmu_exception(CPURISCVState *env, target_ulong address,
 hwaddr riscv_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
+    CPURISCVState *env = &cpu->env;
     hwaddr phys_addr;
     int prot;
     int mmu_idx = cpu_mmu_index(&cpu->env, false);
 
-    if (get_physical_address(&cpu->env, &phys_addr, &prot, addr, 0, mmu_idx,
+    if (get_physical_address(env, &phys_addr, &prot, addr, 0, mmu_idx,
-                             true)) {
+                             true, riscv_cpu_virt_enabled(env))) {
         return -1;
     }
+
+    if (riscv_cpu_virt_enabled(env)) {
+        if (get_physical_address(env, &phys_addr, &prot, phys_addr,
+                                 0, mmu_idx, false, true)) {
+            return -1;
+        }
+    }
+
     return phys_addr;
 }
 
@@ -592,17 +677,37 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
     RISCVCPU *cpu = RISCV_CPU(cs);
     CPURISCVState *env = &cpu->env;
 #ifndef CONFIG_USER_ONLY
+    vaddr im_address;
     hwaddr pa = 0;
     int prot;
     bool pmp_violation = false;
+    bool m_mode_two_stage = false;
+    bool hs_mode_two_stage = false;
+    bool first_stage_error = true;
     int ret = TRANSLATE_FAIL;
     int mode = mmu_idx;
 
+    env->guest_phys_fault_addr = 0;
+
     qemu_log_mask(CPU_LOG_MMU, "%s ad %" VADDR_PRIx " rw %d mmu_idx %d\n",
                   __func__, address, access_type, mmu_idx);
 
-    ret = get_physical_address(env, &pa, &prot, address, access_type, mmu_idx,
+    /*
-                               true);
+     * Determine if we are in M mode and MPRV is set or in HS mode and SPRV is
+     * set and we want to access a virtulisation address.
+     */
+    if (riscv_has_ext(env, RVH)) {
+        m_mode_two_stage = env->priv == PRV_M &&
+                           access_type != MMU_INST_FETCH &&
+                           get_field(env->mstatus, MSTATUS_MPRV) &&
+                           get_field(env->mstatus, MSTATUS_MPV);
+
+        hs_mode_two_stage = env->priv == PRV_S &&
+                            !riscv_cpu_virt_enabled(env) &&
+                            access_type != MMU_INST_FETCH &&
+                            get_field(env->hstatus, HSTATUS_SPRV) &&
+                            get_field(env->hstatus, HSTATUS_SPV);
+    }
 
     if (mode == PRV_M && access_type != MMU_INST_FETCH) {
         if (get_field(env->mstatus, MSTATUS_MPRV)) {
@@ -610,9 +715,55 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
         }
     }
 
-    qemu_log_mask(CPU_LOG_MMU,
+    if (riscv_cpu_virt_enabled(env) || m_mode_two_stage || hs_mode_two_stage) {
-                  "%s address=%" VADDR_PRIx " ret %d physical " TARGET_FMT_plx
+        /* Two stage lookup */
-                  " prot %d\n", __func__, address, ret, pa, prot);
+        ret = get_physical_address(env, &pa, &prot, address, access_type,
+                                   mmu_idx, true, true);
+
+        qemu_log_mask(CPU_LOG_MMU,
+                      "%s 1st-stage address=%" VADDR_PRIx " ret %d physical "
+                      TARGET_FMT_plx " prot %d\n",
+                      __func__, address, ret, pa, prot);
+
+        if (ret != TRANSLATE_FAIL) {
+            /* Second stage lookup */
+            im_address = pa;
+
+            ret = get_physical_address(env, &pa, &prot, im_address,
+                                       access_type, mmu_idx, false, true);
+
+            qemu_log_mask(CPU_LOG_MMU,
+                    "%s 2nd-stage address=%" VADDR_PRIx " ret %d physical "
+                    TARGET_FMT_plx " prot %d\n",
+                    __func__, im_address, ret, pa, prot);
+
+            if (riscv_feature(env, RISCV_FEATURE_PMP) &&
+                (ret == TRANSLATE_SUCCESS) &&
+                !pmp_hart_has_privs(env, pa, size, 1 << access_type, mode)) {
+                ret = TRANSLATE_PMP_FAIL;
+            }
+
+            if (ret != TRANSLATE_SUCCESS) {
+                /*
+                 * Guest physical address translation failed, this is a HS
+                 * level exception
+                 */
+                first_stage_error = false;
+                env->guest_phys_fault_addr = (im_address |
+                                              (address &
+                                               (TARGET_PAGE_SIZE - 1))) >> 2;
+            }
+        }
+    } else {
+        /* Single stage lookup */
+        ret = get_physical_address(env, &pa, &prot, address, access_type,
+                                   mmu_idx, true, false);
+
+        qemu_log_mask(CPU_LOG_MMU,
+                      "%s address=%" VADDR_PRIx " ret %d physical "
+                      TARGET_FMT_plx " prot %d\n",
+                      __func__, address, ret, pa, prot);
+    }
 
     if (riscv_feature(env, RISCV_FEATURE_PMP) &&
         (ret == TRANSLATE_SUCCESS) &&
@@ -622,6 +773,7 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
     if (ret == TRANSLATE_PMP_FAIL) {
         pmp_violation = true;
     }
+
     if (ret == TRANSLATE_SUCCESS) {
         tlb_set_page(cs, address & TARGET_PAGE_MASK, pa & TARGET_PAGE_MASK,
                      prot, mmu_idx, TARGET_PAGE_SIZE);
@@ -629,9 +781,12 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
     } else if (probe) {
         return false;
     } else {
-        raise_mmu_exception(env, address, access_type, pmp_violation, true);
+        raise_mmu_exception(env, address, access_type, pmp_violation, first_stage_error);
         riscv_raise_exception(env, cs->exception_index, retaddr);
     }
+
+    return true;
+
 #else
     switch (access_type) {
     case MMU_INST_FETCH: