qemu

riscv_htif.c (9161B)

---

 /*
  * QEMU RISC-V Host Target Interface (HTIF) Emulation
  *
  * Copyright (c) 2016-2017 Sagar Karandikar, sagark@eecs.berkeley.edu
  * Copyright (c) 2017-2018 SiFive, Inc.
  *
  * This provides HTIF device emulation for QEMU. At the moment this allows
  * for identical copies of bbl/linux to run on both spike and QEMU.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
  * version 2 or later, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/log.h"
 #include "hw/char/riscv_htif.h"
 #include "hw/char/serial.h"
 #include "chardev/char.h"
 #include "chardev/char-fe.h"
 #include "qemu/timer.h"
 #include "qemu/error-report.h"
 
 #define RISCV_DEBUG_HTIF 0
 #define HTIF_DEBUG(fmt, ...)                                                   \
     do {                                                                       \
         if (RISCV_DEBUG_HTIF) {                                                \
             qemu_log_mask(LOG_TRACE, "%s: " fmt "\n", __func__, ##__VA_ARGS__);\
         }                                                                      \
     } while (0)
 
 static uint64_t fromhost_addr, tohost_addr;
 static int address_symbol_set;
 
 void htif_symbol_callback(const char *st_name, int st_info, uint64_t st_value,
                           uint64_t st_size)
 {
     if (strcmp("fromhost", st_name) == 0) {
         address_symbol_set |= 1;
         fromhost_addr = st_value;
         if (st_size != 8) {
             error_report("HTIF fromhost must be 8 bytes");
             exit(1);
         }
     } else if (strcmp("tohost", st_name) == 0) {
         address_symbol_set |= 2;
         tohost_addr = st_value;
         if (st_size != 8) {
             error_report("HTIF tohost must be 8 bytes");
             exit(1);
         }
     }
 }
 
 /*
  * Called by the char dev to see if HTIF is ready to accept input.
  */
 static int htif_can_recv(void *opaque)
 {
     return 1;
 }
 
 /*
  * Called by the char dev to supply input to HTIF console.
  * We assume that we will receive one character at a time.
  */
 static void htif_recv(void *opaque, const uint8_t *buf, int size)
 {
     HTIFState *htifstate = opaque;
 
     if (size != 1) {
         return;
     }
 
     /* TODO - we need to check whether mfromhost is zero which indicates
               the device is ready to receive. The current implementation
               will drop characters */
 
     uint64_t val_written = htifstate->pending_read;
     uint64_t resp = 0x100 | *buf;
 
     htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16);
 }
 
 /*
  * Called by the char dev to supply special events to the HTIF console.
  * Not used for HTIF.
  */
 static void htif_event(void *opaque, QEMUChrEvent event)
 {
 
 }
 
 static int htif_be_change(void *opaque)
 {
     HTIFState *s = opaque;
 
     qemu_chr_fe_set_handlers(&s->chr, htif_can_recv, htif_recv, htif_event,
         htif_be_change, s, NULL, true);
 
     return 0;
 }
 
 static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written)
 {
     uint8_t device = val_written >> 56;
     uint8_t cmd = val_written >> 48;
     uint64_t payload = val_written & 0xFFFFFFFFFFFFULL;
     int resp = 0;
 
     HTIF_DEBUG("mtohost write: device: %d cmd: %d what: %02" PRIx64
         " -payload: %016" PRIx64 "\n", device, cmd, payload & 0xFF, payload);
 
     /*
      * Currently, there is a fixed mapping of devices:
      * 0: riscv-tests Pass/Fail Reporting Only (no syscall proxy)
      * 1: Console
      */
     if (unlikely(device == 0x0)) {
         /* frontend syscall handler, shutdown and exit code support */
         if (cmd == 0x0) {
             if (payload & 0x1) {
                 /* exit code */
                 int exit_code = payload >> 1;
                 exit(exit_code);
             } else {
                 qemu_log_mask(LOG_UNIMP, "pk syscall proxy not supported\n");
             }
         } else {
             qemu_log("HTIF device %d: unknown command\n", device);
         }
     } else if (likely(device == 0x1)) {
         /* HTIF Console */
         if (cmd == 0x0) {
             /* this should be a queue, but not yet implemented as such */
             htifstate->pending_read = val_written;
             htifstate->env->mtohost = 0; /* clear to indicate we read */
             return;
         } else if (cmd == 0x1) {
             qemu_chr_fe_write(&htifstate->chr, (uint8_t *)&payload, 1);
             resp = 0x100 | (uint8_t)payload;
         } else {
             qemu_log("HTIF device %d: unknown command\n", device);
         }
     } else {
         qemu_log("HTIF unknown device or command\n");
         HTIF_DEBUG("device: %d cmd: %d what: %02" PRIx64
             " payload: %016" PRIx64, device, cmd, payload & 0xFF, payload);
     }
     /*
      * - latest bbl does not set fromhost to 0 if there is a value in tohost
      * - with this code enabled, qemu hangs waiting for fromhost to go to 0
      * - with this code disabled, qemu works with bbl priv v1.9.1 and v1.10
      * - HTIF needs protocol documentation and a more complete state machine
 
         while (!htifstate->fromhost_inprogress &&
             htifstate->env->mfromhost != 0x0) {
         }
     */
     htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16);
     htifstate->env->mtohost = 0; /* clear to indicate we read */
 }
 
 #define TOHOST_OFFSET1 (htifstate->tohost_offset)
 #define TOHOST_OFFSET2 (htifstate->tohost_offset + 4)
 #define FROMHOST_OFFSET1 (htifstate->fromhost_offset)
 #define FROMHOST_OFFSET2 (htifstate->fromhost_offset + 4)
 
 /* CPU wants to read an HTIF register */
 static uint64_t htif_mm_read(void *opaque, hwaddr addr, unsigned size)
 {
     HTIFState *htifstate = opaque;
     if (addr == TOHOST_OFFSET1) {
         return htifstate->env->mtohost & 0xFFFFFFFF;
     } else if (addr == TOHOST_OFFSET2) {
         return (htifstate->env->mtohost >> 32) & 0xFFFFFFFF;
     } else if (addr == FROMHOST_OFFSET1) {
         return htifstate->env->mfromhost & 0xFFFFFFFF;
     } else if (addr == FROMHOST_OFFSET2) {
         return (htifstate->env->mfromhost >> 32) & 0xFFFFFFFF;
     } else {
         qemu_log("Invalid htif read: address %016" PRIx64 "\n",
             (uint64_t)addr);
         return 0;
     }
 }
 
 /* CPU wrote to an HTIF register */
 static void htif_mm_write(void *opaque, hwaddr addr,
                             uint64_t value, unsigned size)
 {
     HTIFState *htifstate = opaque;
     if (addr == TOHOST_OFFSET1) {
         if (htifstate->env->mtohost == 0x0) {
             htifstate->allow_tohost = 1;
             htifstate->env->mtohost = value & 0xFFFFFFFF;
         } else {
             htifstate->allow_tohost = 0;
         }
     } else if (addr == TOHOST_OFFSET2) {
         if (htifstate->allow_tohost) {
             htifstate->env->mtohost |= value << 32;
             htif_handle_tohost_write(htifstate, htifstate->env->mtohost);
         }
     } else if (addr == FROMHOST_OFFSET1) {
         htifstate->fromhost_inprogress = 1;
         htifstate->env->mfromhost = value & 0xFFFFFFFF;
     } else if (addr == FROMHOST_OFFSET2) {
         htifstate->env->mfromhost |= value << 32;
         htifstate->fromhost_inprogress = 0;
     } else {
         qemu_log("Invalid htif write: address %016" PRIx64 "\n",
             (uint64_t)addr);
     }
 }
 
 static const MemoryRegionOps htif_mm_ops = {
     .read = htif_mm_read,
     .write = htif_mm_write,
 };
 
 bool htif_uses_elf_symbols(void)
 {
     return (address_symbol_set == 3) ? true : false;
 }
 
 HTIFState *htif_mm_init(MemoryRegion *address_space, MemoryRegion *main_mem,
     CPURISCVState *env, Chardev *chr, uint64_t nonelf_base)
 {
     uint64_t base, size, tohost_offset, fromhost_offset;
 
     if (!htif_uses_elf_symbols()) {
         fromhost_addr = nonelf_base;
         tohost_addr = nonelf_base + 8;
     }
 
     base = MIN(tohost_addr, fromhost_addr);
     size = MAX(tohost_addr + 8, fromhost_addr + 8) - base;
     tohost_offset = tohost_addr - base;
     fromhost_offset = fromhost_addr - base;
 
     HTIFState *s = g_new0(HTIFState, 1);
     s->address_space = address_space;
     s->main_mem = main_mem;
     s->main_mem_ram_ptr = memory_region_get_ram_ptr(main_mem);
     s->env = env;
     s->tohost_offset = tohost_offset;
     s->fromhost_offset = fromhost_offset;
     s->pending_read = 0;
     s->allow_tohost = 0;
     s->fromhost_inprogress = 0;
     qemu_chr_fe_init(&s->chr, chr, &error_abort);
     qemu_chr_fe_set_handlers(&s->chr, htif_can_recv, htif_recv, htif_event,
         htif_be_change, s, NULL, true);
 
     memory_region_init_io(&s->mmio, NULL, &htif_mm_ops, s,
                           TYPE_HTIF_UART, size);
     memory_region_add_subregion_overlap(address_space, base,
                                         &s->mmio, 1);
 
     return s;
 }