target-ppc/kvm_ppc.c

   1 /*
   2  * PowerPC KVM support
   3  *
   4  * Copyright IBM Corp. 2008
   5  *
   6  * Authors:
   7  *  Hollis Blanchard <hollisb@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "qemu-timer.h"
  16 #include "kvm_ppc.h"
  17 #include "device_tree.h"
  18
  19 #define PROC_DEVTREE_PATH "/proc/device-tree"
  20
  21 static QEMUTimer *kvmppc_timer;
  22 static unsigned int kvmppc_timer_rate;
  23
  24 #ifdef CONFIG_FDT
  25 int kvmppc_read_host_property(const char *node_path, const char *prop,
  26                                      void *val, size_t len)
  27 {
  28     char *path;
  29     FILE *f;
  30     int ret = 0;
  31     int pathlen;
  32
  33     pathlen = snprintf(NULL, 0, "%s/%s/%s", PROC_DEVTREE_PATH, node_path, prop)
  34               + 1;
  35     path = g_malloc(pathlen);
  36
  37     snprintf(path, pathlen, "%s/%s/%s", PROC_DEVTREE_PATH, node_path, prop);
  38
  39     f = fopen(path, "rb");
  40     if (f == NULL) {
  41         ret = errno;
  42         goto free;
  43     }
  44
  45     len = fread(val, len, 1, f);
  46     if (len != 1) {
  47         ret = ferror(f);
  48         goto close;
  49     }
  50
  51 close:
  52     fclose(f);
  53 free:
  54     free(path);
  55     return ret;
  56 }
  57
  58 static int kvmppc_copy_host_cell(void *fdt, const char *node, const char *prop)
  59 {
  60     uint32_t cell;
  61     int ret;
  62
  63     ret = kvmppc_read_host_property(node, prop, &cell, sizeof(cell));
  64     if (ret < 0) {
  65         fprintf(stderr, "couldn't read host %s/%s\n", node, prop);
  66         goto out;
  67     }
  68
  69     ret = qemu_devtree_setprop_cell(fdt, node, prop, cell);
  70     if (ret < 0) {
  71         fprintf(stderr, "couldn't set guest %s/%s\n", node, prop);
  72         goto out;
  73     }
  74
  75 out:
  76     return ret;
  77 }
  78
  79 void kvmppc_fdt_update(void *fdt)
  80 {
  81     /* Copy data from the host device tree into the guest. Since the guest can
  82      * directly access the timebase without host involvement, we must expose
  83      * the correct frequencies. */
  84     kvmppc_copy_host_cell(fdt, "/cpus/cpu@0", "clock-frequency");
  85     kvmppc_copy_host_cell(fdt, "/cpus/cpu@0", "timebase-frequency");
  86 }
  87 #endif
  88
  89 static void kvmppc_timer_hack(void *opaque)
  90 {
  91     qemu_service_io();
  92     qemu_mod_timer(kvmppc_timer, qemu_get_clock_ns(vm_clock) + kvmppc_timer_rate);
  93 }
  94
  95 void kvmppc_init(void)
  96 {
  97     /* XXX The only reason KVM yields control back to qemu is device IO. Since
  98      * an idle guest does no IO, qemu's device model will never get a chance to
  99      * run. So, until Qemu gains IO threads, we create this timer to ensure
 100      * that the device model gets a chance to run. */
 101     kvmppc_timer_rate = get_ticks_per_sec() / 10;
 102     kvmppc_timer = qemu_new_timer_ns(vm_clock, &kvmppc_timer_hack, NULL);
 103     qemu_mod_timer(kvmppc_timer, qemu_get_clock_ns(vm_clock) + kvmppc_timer_rate);
 104 }
 105