Merge remote-tracking branch 'remotes/riscv/tags/riscv-for-master-3.1-sf0' into staging

First RISC-V Patch Set for the 3.1 Soft Freeze

This pull request contains a handful of patches that have been floating
around various trees for a while but haven't made it upstream.  These
patches all appear quite safe.  They're all somewhat independent from
each other:

* One refactors our IRQ management function to allow multiple interrupts
  to be raised an once.  This patch has no functional difference.
* Cleaning up the op_helper/cpu_helper split.  This patch has no
  functional difference.
* Updates to various constants to keep them in sync with the latest ISA
  specification and to remove some non-standard bits that snuck in.
* A fix for a memory leak in the PLIC driver.
* A fix to our device tree handling to avoid provinging a NULL string.

I've given this my standard test: building the port, booting a Fedora
root filesytem on the latest Linux tag, and then shutting down that
image.  Essentially I'm just following the QEMU RISC-V wiki page's
instructions.  Everything looks fine here.

We have a lot more outstanding patches so I'll definately be submitting
another PR for the soft freeze.

# gpg: Signature made Wed 17 Oct 2018 21:17:52 BST
# gpg:                using RSA key EF4CA1502CCBAB41
# gpg: Good signature from "Palmer Dabbelt <palmer@dabbelt.com>"
# gpg:                 aka "Palmer Dabbelt <palmer@sifive.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 00CE 76D1 8349 60DF CE88  6DF8 EF4C A150 2CCB AB41

* remotes/riscv/tags/riscv-for-master-3.1-sf0:
  RISC-V: Don't add NULL bootargs to device-tree
  RISC-V: Add missing free for plic_hart_config
  RISC-V: Update CSR and interrupt definitions
  RISC-V: Move non-ops from op_helper to cpu_helper
  RISC-V: Allow setting and clearing multiple irqs

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

hw/riscv/sifive_clint.c

@@ -47,12 +47,12 @@ static void sifive_clint_write_timecmp(RISCVCPU *cpu, uint64_t value)
     if (cpu->env.timecmp <= rtc_r) {
         /* if we're setting an MTIMECMP value in the "past",
            immediately raise the timer interrupt */
-        riscv_set_local_interrupt(cpu, MIP_MTIP, 1);
+        riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(1));
         return;
     }
 
     /* otherwise, set up the future timer interrupt */
-    riscv_set_local_interrupt(cpu, MIP_MTIP, 0);
+    riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(0));
     diff = cpu->env.timecmp - rtc_r;
     /* back to ns (note args switched in muldiv64) */
     next = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
@@ -67,7 +67,7 @@ static void sifive_clint_write_timecmp(RISCVCPU *cpu, uint64_t value)
 static void sifive_clint_timer_cb(void *opaque)
 {
     RISCVCPU *cpu = opaque;
-    riscv_set_local_interrupt(cpu, MIP_MTIP, 1);
+    riscv_cpu_update_mip(cpu, MIP_MTIP, BOOL_TO_MASK(1));
 }
 
 /* CPU wants to read rtc or timecmp register */
@@ -132,7 +132,7 @@ static void sifive_clint_write(void *opaque, hwaddr addr, uint64_t value,
         if (!env) {
             error_report("clint: invalid timecmp hartid: %zu", hartid);
         } else if ((addr & 0x3) == 0) {
-            riscv_set_local_interrupt(RISCV_CPU(cpu), MIP_MSIP, value != 0);
+            riscv_cpu_update_mip(RISCV_CPU(cpu), MIP_MSIP, BOOL_TO_MASK(value));
         } else {
             error_report("clint: invalid sip write: %08x", (uint32_t)addr);
         }

hw/riscv/sifive_plic.c

@@ -142,10 +142,10 @@ static void sifive_plic_update(SiFivePLICState *plic)
         int level = sifive_plic_irqs_pending(plic, addrid);
         switch (mode) {
         case PLICMode_M:
-            riscv_set_local_interrupt(RISCV_CPU(cpu), MIP_MEIP, level);
+            riscv_cpu_update_mip(RISCV_CPU(cpu), MIP_MEIP, BOOL_TO_MASK(level));
             break;
         case PLICMode_S:
-            riscv_set_local_interrupt(RISCV_CPU(cpu), MIP_SEIP, level);
+            riscv_cpu_update_mip(RISCV_CPU(cpu), MIP_SEIP, BOOL_TO_MASK(level));
             break;
         default:
             break;

hw/riscv/sifive_u.c

@@ -230,7 +230,9 @@ static void create_fdt(SiFiveUState *s, const struct MemmapEntry *memmap,
 
     qemu_fdt_add_subnode(fdt, "/chosen");
     qemu_fdt_setprop_string(fdt, "/chosen", "stdout-path", nodename);
-    qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
+    if (cmdline) {
+        qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
+    }
     g_free(nodename);
 }
 

hw/riscv/spike.c

@@ -156,8 +156,10 @@ static void create_fdt(SpikeState *s, const struct MemmapEntry *memmap,
     g_free(cells);
     g_free(nodename);
 
-    qemu_fdt_add_subnode(fdt, "/chosen");
-    qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
+    if (cmdline) {
+        qemu_fdt_add_subnode(fdt, "/chosen");
+        qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
+    }
  }
 
 static void spike_v1_10_0_board_init(MachineState *machine)

hw/riscv/virt.c

@@ -254,7 +254,9 @@ static void *create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap,
 
     qemu_fdt_add_subnode(fdt, "/chosen");
     qemu_fdt_setprop_string(fdt, "/chosen", "stdout-path", nodename);
-    qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
+    if (cmdline) {
+        qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
+    }
     g_free(nodename);
 
     return fdt;
@@ -385,6 +387,8 @@ static void riscv_virt_board_init(MachineState *machine)
     serial_mm_init(system_memory, memmap[VIRT_UART0].base,
         0, qdev_get_gpio_in(DEVICE(s->plic), UART0_IRQ), 399193,
         serial_hd(0), DEVICE_LITTLE_ENDIAN);
+
+    g_free(plic_hart_config);
 }
 
 static void riscv_virt_board_machine_init(MachineClass *mc)

target/riscv/Makefile.objs

@@ -1 +1 @@
-obj-y += translate.o op_helper.o helper.o cpu.o fpu_helper.o gdbstub.o pmp.o
+obj-y += translate.o op_helper.o cpu_helper.o cpu.o fpu_helper.o gdbstub.o pmp.o

target/riscv/cpu.c

@@ -74,8 +74,10 @@ const char * const riscv_intr_names[] = {
     "s_external",
     "h_external",
     "m_external",
-    "coprocessor",
-    "host"
+    "reserved",
+    "reserved",
+    "reserved",
+    "reserved"
 };
 
 typedef struct RISCVCPUInfo {

target/riscv/cpu.h

@@ -126,13 +126,18 @@ struct CPURISCVState {
 
     target_ulong mhartid;
     target_ulong mstatus;
+
     /*
      * CAUTION! Unlike the rest of this struct, mip is accessed asynchonously
-     * by I/O threads and other vCPUs, so hold the iothread mutex before
-     * operating on it.  CPU_INTERRUPT_HARD should be in effect iff this is
-     * non-zero.  Use riscv_cpu_set_local_interrupt.
+     * by I/O threads. It should be read with atomic_read. It should be updated
+     * using riscv_cpu_update_mip with the iothread mutex held. The iothread
+     * mutex must be held because mip must be consistent with the CPU inturrept
+     * state. riscv_cpu_update_mip calls cpu_interrupt or cpu_reset_interrupt
+     * wuth the invariant that CPU_INTERRUPT_HARD is set iff mip is non-zero.
+     * mip is 32-bits to allow atomic_read on 32-bit hosts.
      */
-    uint32_t mip;        /* allow atomic_read for >= 32-bit hosts */
+    uint32_t mip;
+
     target_ulong mie;
     target_ulong mideleg;
 
@@ -247,7 +252,6 @@ void  riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
                                     uintptr_t retaddr);
 int riscv_cpu_handle_mmu_fault(CPUState *cpu, vaddr address, int size,
                               int rw, int mmu_idx);
-
 char *riscv_isa_string(RISCVCPU *cpu);
 void riscv_cpu_list(FILE *f, fprintf_function cpu_fprintf);
 
@@ -255,6 +259,10 @@ void riscv_cpu_list(FILE *f, fprintf_function cpu_fprintf);
 #define cpu_list riscv_cpu_list
 #define cpu_mmu_index riscv_cpu_mmu_index
 
+#ifndef CONFIG_USER_ONLY
+uint32_t riscv_cpu_update_mip(RISCVCPU *cpu, uint32_t mask, uint32_t value);
+#define BOOL_TO_MASK(x) (-!!(x)) /* helper for riscv_cpu_update_mip value */
+#endif
 void riscv_set_mode(CPURISCVState *env, target_ulong newpriv);
 
 void riscv_translate_init(void);
@@ -285,10 +293,6 @@ void csr_write_helper(CPURISCVState *env, target_ulong val_to_write,
         target_ulong csrno);
 target_ulong csr_read_helper(CPURISCVState *env, target_ulong csrno);
 
-#ifndef CONFIG_USER_ONLY
-void riscv_set_local_interrupt(RISCVCPU *cpu, target_ulong mask, int value);
-#endif
-
 #include "exec/cpu-all.h"
 
 #endif /* RISCV_CPU_H */

target/riscv/cpu_helper.c

@@ -1,5 +1,5 @@
 /*
- * RISC-V emulation helpers for qemu.
+ * RISC-V CPU helpers for qemu.
  *
  * Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
  * Copyright (c) 2017-2018 SiFive, Inc.
@@ -72,6 +72,39 @@ bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
 
 #if !defined(CONFIG_USER_ONLY)
 
+/* iothread_mutex must be held */
+uint32_t riscv_cpu_update_mip(RISCVCPU *cpu, uint32_t mask, uint32_t value)
+{
+    CPURISCVState *env = &cpu->env;
+    uint32_t old, new, cmp = atomic_read(&env->mip);
+
+    do {
+        old = cmp;
+        new = (old & ~mask) | (value & mask);
+        cmp = atomic_cmpxchg(&env->mip, old, new);
+    } while (old != cmp);
+
+    if (new && !old) {
+        cpu_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
+    } else if (!new && old) {
+        cpu_reset_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
+    }
+
+    return old;
+}
+
+void riscv_set_mode(CPURISCVState *env, target_ulong newpriv)
+{
+    if (newpriv > PRV_M) {
+        g_assert_not_reached();
+    }
+    if (newpriv == PRV_H) {
+        newpriv = PRV_U;
+    }
+    /* tlb_flush is unnecessary as mode is contained in mmu_idx */
+    env->priv = newpriv;
+}
+
 /* get_physical_address - get the physical address for this virtual address
  *
  * Do a page table walk to obtain the physical address corresponding to a

target/riscv/op_helper.c

@@ -90,7 +90,7 @@ void csr_write_helper(CPURISCVState *env, target_ulong val_to_write,
         target_ulong csrno)
 {
 #ifndef CONFIG_USER_ONLY
-    uint64_t delegable_ints = MIP_SSIP | MIP_STIP | MIP_SEIP | (1 << IRQ_X_COP);
+    uint64_t delegable_ints = MIP_SSIP | MIP_STIP | MIP_SEIP;
     uint64_t all_ints = delegable_ints | MIP_MSIP | MIP_MTIP;
 #endif
 
@@ -171,10 +171,8 @@ void csr_write_helper(CPURISCVState *env, target_ulong val_to_write,
          */
         qemu_mutex_lock_iothread();
         RISCVCPU *cpu = riscv_env_get_cpu(env);
-        riscv_set_local_interrupt(cpu, MIP_SSIP,
-                                  (val_to_write & MIP_SSIP) != 0);
-        riscv_set_local_interrupt(cpu, MIP_STIP,
-                                  (val_to_write & MIP_STIP) != 0);
+        riscv_cpu_update_mip(cpu, MIP_SSIP | MIP_STIP,
+                                  (val_to_write & (MIP_SSIP | MIP_STIP)));
         /*
          * csrs, csrc on mip.SEIP is not decomposable into separate read and
          * write steps, so a different implementation is needed
@@ -656,31 +654,6 @@ target_ulong helper_csrrc(CPURISCVState *env, target_ulong src,
 
 #ifndef CONFIG_USER_ONLY
 
-/* iothread_mutex must be held */
-void riscv_set_local_interrupt(RISCVCPU *cpu, target_ulong mask, int value)
-{
-    target_ulong old_mip = cpu->env.mip;
-    cpu->env.mip = (old_mip & ~mask) | (value ? mask : 0);
-
-    if (cpu->env.mip && !old_mip) {
-        cpu_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
-    } else if (!cpu->env.mip && old_mip) {
-        cpu_reset_interrupt(CPU(cpu), CPU_INTERRUPT_HARD);
-    }
-}
-
-void riscv_set_mode(CPURISCVState *env, target_ulong newpriv)
-{
-    if (newpriv > PRV_M) {
-        g_assert_not_reached();
-    }
-    if (newpriv == PRV_H) {
-        newpriv = PRV_U;
-    }
-    /* tlb_flush is unnecessary as mode is contained in mmu_idx */
-    env->priv = newpriv;
-}
-
 target_ulong helper_sret(CPURISCVState *env, target_ulong cpu_pc_deb)
 {
     if (!(env->priv >= PRV_S)) {
@@ -731,7 +704,6 @@ target_ulong helper_mret(CPURISCVState *env, target_ulong cpu_pc_deb)
     return retpc;
 }
 
-
 void helper_wfi(CPURISCVState *env)
 {
     CPUState *cs = CPU(riscv_env_get_cpu(env));