Merge remote-tracking branch 'remotes/alistair/tags/pull-riscv-pullreq-20180905' into staging

A misc collection of RISC-V related patches for 3.1.

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# gpg:                using RSA key 21E10D29DF977054
# gpg: Good signature from "Alistair Francis <alistair@alistair23.me>"
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* remotes/alistair/tags/pull-riscv-pullreq-20180905:
  riscv: remove define cpu_init()
  hw/riscv/spike: Set the soc device tree node as a simple-bus
  hw/riscv/virtio: Set the soc device tree node as a simple-bus
  target/riscv: call gen_goto_tb on DISAS_TOO_MANY
  target/riscv: optimize indirect branches
  target/riscv: optimize cross-page direct jumps in softmmu
  RISC-V: Simplify riscv_cpu_local_irqs_pending
  RISC-V: Use atomic_cmpxchg to update PLIC bitmaps
  RISC-V: Improve page table walker spec compliance
  RISC-V: Update address bits to support sv39 and sv48

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

4 files changed, 64 insertions, 56 deletions

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 34abc383e3..d4f36295f0 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -24,12 +24,12 @@
 #define TARGET_PAGE_BITS 12 /* 4 KiB Pages */
 #if defined(TARGET_RISCV64)
 #define TARGET_LONG_BITS 64
-#define TARGET_PHYS_ADDR_SPACE_BITS 50
-#define TARGET_VIRT_ADDR_SPACE_BITS 39
+#define TARGET_PHYS_ADDR_SPACE_BITS 56 /* 44-bit PPN */
+#define TARGET_VIRT_ADDR_SPACE_BITS 48 /* sv48 */
 #elif defined(TARGET_RISCV32)
 #define TARGET_LONG_BITS 32
-#define TARGET_PHYS_ADDR_SPACE_BITS 34
-#define TARGET_VIRT_ADDR_SPACE_BITS 32
+#define TARGET_PHYS_ADDR_SPACE_BITS 34 /* 22-bit PPN */
+#define TARGET_VIRT_ADDR_SPACE_BITS 32 /* sv32 */
 #endif
 
 #define TCG_GUEST_DEFAULT_MO 0
@@ -251,7 +251,6 @@ int riscv_cpu_handle_mmu_fault(CPUState *cpu, vaddr address, int size,
 char *riscv_isa_string(RISCVCPU *cpu);
 void riscv_cpu_list(FILE *f, fprintf_function cpu_fprintf);
 
-#define cpu_init(cpu_model) cpu_generic_init(TYPE_RISCV_CPU, cpu_model)
 #define cpu_signal_handler cpu_riscv_signal_handler
 #define cpu_list riscv_cpu_list
 #define cpu_mmu_index riscv_cpu_mmu_index
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 64aa097181..12b4757088 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -407,5 +407,3 @@
 #define PTE_SOFT  0x300 /* Reserved for Software */
 
 #define PTE_PPN_SHIFT 10
-
-#define PTE_TABLE(PTE) (((PTE) & (PTE_V | PTE_R | PTE_W | PTE_X)) == PTE_V)
diff --git a/target/riscv/helper.c b/target/riscv/helper.c
index 29e1a603dc..63b3386b76 100644
--- a/target/riscv/helper.c
+++ b/target/riscv/helper.c
@@ -35,28 +35,18 @@ int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
 }
 
 #ifndef CONFIG_USER_ONLY
-/*
- * Return RISC-V IRQ number if an interrupt should be taken, else -1.
- * Used in cpu-exec.c
- *
- * Adapted from Spike's processor_t::take_interrupt()
- */
-static int riscv_cpu_hw_interrupts_pending(CPURISCVState *env)
+static int riscv_cpu_local_irq_pending(CPURISCVState *env)
 {
-    target_ulong pending_interrupts = atomic_read(&env->mip) & env->mie;
-
-    target_ulong mie = get_field(env->mstatus, MSTATUS_MIE);
-    target_ulong m_enabled = env->priv < PRV_M || (env->priv == PRV_M && mie);
-    target_ulong enabled_interrupts = pending_interrupts &
-                                      ~env->mideleg & -m_enabled;
-
-    target_ulong sie = get_field(env->mstatus, MSTATUS_SIE);
-    target_ulong s_enabled = env->priv < PRV_S || (env->priv == PRV_S && sie);
-    enabled_interrupts |= pending_interrupts & env->mideleg &
-                          -s_enabled;
-
-    if (enabled_interrupts) {
-        return ctz64(enabled_interrupts); /* since non-zero */
+    target_ulong mstatus_mie = get_field(env->mstatus, MSTATUS_MIE);
+    target_ulong mstatus_sie = get_field(env->mstatus, MSTATUS_SIE);
+    target_ulong pending = atomic_read(&env->mip) & env->mie;
+    target_ulong mie = env->priv < PRV_M || (env->priv == PRV_M && mstatus_mie);
+    target_ulong sie = env->priv < PRV_S || (env->priv == PRV_S && mstatus_sie);
+    target_ulong irqs = (pending & ~env->mideleg & -mie) |
+                        (pending &  env->mideleg & -sie);
+
+    if (irqs) {
+        return ctz64(irqs); /* since non-zero */
     } else {
         return EXCP_NONE; /* indicates no pending interrupt */
     }
@@ -69,7 +59,7 @@ bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
     if (interrupt_request & CPU_INTERRUPT_HARD) {
         RISCVCPU *cpu = RISCV_CPU(cs);
         CPURISCVState *env = &cpu->env;
-        int interruptno = riscv_cpu_hw_interrupts_pending(env);
+        int interruptno = riscv_cpu_local_irq_pending(env);
         if (interruptno >= 0) {
             cs->exception_index = RISCV_EXCP_INT_FLAG | interruptno;
             riscv_cpu_do_interrupt(cs);
@@ -185,16 +175,39 @@ restart:
 #endif
         target_ulong ppn = pte >> PTE_PPN_SHIFT;
 
-        if (PTE_TABLE(pte)) { /* next level of page table */
+        if (!(pte & PTE_V)) {
+            /* Invalid PTE */
+            return TRANSLATE_FAIL;
+        } else if (!(pte & (PTE_R | PTE_W | PTE_X))) {
+            /* Inner PTE, continue walking */
             base = ppn << PGSHIFT;
-        } else if ((pte & PTE_U) ? (mode == PRV_S) && !sum : !(mode == PRV_S)) {
-            break;
-        } else if (!(pte & PTE_V) || (!(pte & PTE_R) && (pte & PTE_W))) {
-            break;
-        } else if (access_type == MMU_INST_FETCH ? !(pte & PTE_X) :
-                  access_type == MMU_DATA_LOAD ?  !(pte & PTE_R) &&
-                  !(mxr && (pte & PTE_X)) : !((pte & PTE_R) && (pte & PTE_W))) {
-            break;
+        } else if ((pte & (PTE_R | PTE_W | PTE_X)) == PTE_W) {
+            /* Reserved leaf PTE flags: PTE_W */
+            return TRANSLATE_FAIL;
+        } else if ((pte & (PTE_R | PTE_W | PTE_X)) == (PTE_W | PTE_X)) {
+            /* Reserved leaf PTE flags: PTE_W + PTE_X */
+            return TRANSLATE_FAIL;
+        } else if ((pte & PTE_U) && ((mode != PRV_U) &&
+                   (!sum || access_type == MMU_INST_FETCH))) {
+            /* User PTE flags when not U mode and mstatus.SUM is not set,
+               or the access type is an instruction fetch */
+            return TRANSLATE_FAIL;
+        } else if (!(pte & PTE_U) && (mode != PRV_S)) {
+            /* Supervisor PTE flags when not S mode */
+            return TRANSLATE_FAIL;
+        } else if (ppn & ((1ULL << ptshift) - 1)) {
+            /* Misaligned PPN */
+            return TRANSLATE_FAIL;
+        } else if (access_type == MMU_DATA_LOAD && !((pte & PTE_R) ||
+                   ((pte & PTE_X) && mxr))) {
+            /* Read access check failed */
+            return TRANSLATE_FAIL;
+        } else if (access_type == MMU_DATA_STORE && !(pte & PTE_W)) {
+            /* Write access check failed */
+            return TRANSLATE_FAIL;
+        } else if (access_type == MMU_INST_FETCH && !(pte & PTE_X)) {
+            /* Fetch access check failed */
+            return TRANSLATE_FAIL;
         } else {
             /* if necessary, set accessed and dirty bits. */
             target_ulong updated_pte = pte | PTE_A |
@@ -202,16 +215,19 @@ restart:
 
             /* Page table updates need to be atomic with MTTCG enabled */
             if (updated_pte != pte) {
-                /* if accessed or dirty bits need updating, and the PTE is
-                 * in RAM, then we do so atomically with a compare and swap.
-                 * if the PTE is in IO space, then it can't be updated.
-                 * if the PTE changed, then we must re-walk the page table
-                   as the PTE is no longer valid */
+                /*
+                 * - if accessed or dirty bits need updating, and the PTE is
+                 *   in RAM, then we do so atomically with a compare and swap.
+                 * - if the PTE is in IO space or ROM, then it can't be updated
+                 *   and we return TRANSLATE_FAIL.
+                 * - if the PTE changed by the time we went to update it, then
+                 *   it is no longer valid and we must re-walk the page table.
+                 */
                 MemoryRegion *mr;
                 hwaddr l = sizeof(target_ulong), addr1;
                 mr = address_space_translate(cs->as, pte_addr,
                     &addr1, &l, false, MEMTXATTRS_UNSPECIFIED);
-                if (memory_access_is_direct(mr, true)) {
+                if (memory_region_is_ram(mr)) {
                     target_ulong *pte_pa =
                         qemu_map_ram_ptr(mr->ram_block, addr1);
 #if TCG_OVERSIZED_GUEST
@@ -239,15 +255,15 @@ restart:
             target_ulong vpn = addr >> PGSHIFT;
             *physical = (ppn | (vpn & ((1L << ptshift) - 1))) << PGSHIFT;
 
-            if ((pte & PTE_R)) {
+            /* set permissions on the TLB entry */
+            if ((pte & PTE_R) || ((pte & PTE_X) && mxr)) {
                 *prot |= PAGE_READ;
             }
             if ((pte & PTE_X)) {
                 *prot |= PAGE_EXEC;
             }
-           /* only add write permission on stores or if the page
-              is already dirty, so that we don't miss further
-              page table walks to update the dirty bit */
+            /* add write permission on stores or if the page is already dirty,
+               so that we TLB miss on later writes to update the dirty bit */
             if ((pte & PTE_W) &&
                     (access_type == MMU_DATA_STORE || (pte & PTE_D))) {
                 *prot |= PAGE_WRITE;
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 0b6be74f2d..18d7b6d147 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -135,7 +135,7 @@ static void gen_goto_tb(DisasContext *ctx, int n, target_ulong dest)
         if (ctx->base.singlestep_enabled) {
             gen_exception_debug();
         } else {
-            tcg_gen_exit_tb(NULL, 0);
+            tcg_gen_lookup_and_goto_ptr();
         }
     }
 }
@@ -548,7 +548,7 @@ static void gen_jalr(CPURISCVState *env, DisasContext *ctx, uint32_t opc,
         if (rd != 0) {
             tcg_gen_movi_tl(cpu_gpr[rd], ctx->pc_succ_insn);
         }
-        tcg_gen_exit_tb(NULL, 0);
+        tcg_gen_lookup_and_goto_ptr();
 
         if (misaligned) {
             gen_set_label(misaligned);
@@ -1868,12 +1868,7 @@ static void riscv_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
 
     switch (ctx->base.is_jmp) {
     case DISAS_TOO_MANY:
-        tcg_gen_movi_tl(cpu_pc, ctx->base.pc_next);
-        if (ctx->base.singlestep_enabled) {
-            gen_exception_debug();
-        } else {
-            tcg_gen_exit_tb(NULL, 0);
-        }
+        gen_goto_tb(ctx, 0, ctx->base.pc_next);
         break;
     case DISAS_NORETURN:
         break;