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 HAVE_FDT
  25 static 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;
  31     int pathlen;
  32
  33     pathlen = snprintf(NULL, 0, "%s/%s/%s", PROC_DEVTREE_PATH, node_path, prop)
  34               + 1;
  35     path = qemu_malloc(pathlen);
  36     if (path == NULL) {
  37         ret = -ENOMEM;
  38         goto out;
  39     }
  40
  41     snprintf(path, pathlen, "%s/%s/%s", PROC_DEVTREE_PATH, node_path, prop);
  42
  43     f = fopen(path, "rb");
  44     if (f == NULL) {
  45         ret = errno;
  46         goto free;
  47     }
  48
  49     len = fread(val, len, 1, f);
  50     if (len != 1) {
  51         ret = ferror(f);
  52         goto close;
  53     }
  54
  55 close:
  56     fclose(f);
  57 free:
  58     free(path);
  59 out:
  60     return ret;
  61 }
  62
  63 static int kvmppc_copy_host_cell(void *fdt, const char *node, const char *prop)
  64 {
  65     uint32_t cell;
  66     int ret;
  67
  68     ret = kvmppc_read_host_property(node, prop, &cell, sizeof(cell));
  69     if (ret < 0) {
  70         fprintf(stderr, "couldn't read host %s/%s\n", node, prop);
  71         goto out;
  72     }
  73
  74     ret = qemu_devtree_setprop_cell(fdt, node, prop, cell);
  75     if (ret < 0) {
  76         fprintf(stderr, "couldn't set guest %s/%s\n", node, prop);
  77         goto out;
  78     }
  79
  80 out:
  81     return ret;
  82 }
  83
  84 void kvmppc_fdt_update(void *fdt)
  85 {
  86     /* Copy data from the host device tree into the guest. Since the guest can
  87      * directly access the timebase without host involvement, we must expose
  88      * the correct frequencies. */
  89     kvmppc_copy_host_cell(fdt, "/cpus/cpu@0", "clock-frequency");
  90     kvmppc_copy_host_cell(fdt, "/cpus/cpu@0", "timebase-frequency");
  91 }
  92 #endif
  93
  94 static void kvmppc_timer_hack(void *opaque)
  95 {
  96     qemu_service_io();
  97     qemu_mod_timer(kvmppc_timer, qemu_get_clock(vm_clock) + kvmppc_timer_rate);
  98 }
  99
 100 void kvmppc_init(void)
 101 {
 102     /* XXX The only reason KVM yields control back to qemu is device IO. Since
 103      * an idle guest does no IO, qemu's device model will never get a chance to
 104      * run. So, until Qemu gains IO threads, we create this timer to ensure
 105      * that the device model gets a chance to run. */
 106     kvmppc_timer_rate = ticks_per_sec / 10;
 107     kvmppc_timer = qemu_new_timer(vm_clock, &kvmppc_timer_hack, NULL);
 108     qemu_mod_timer(kvmppc_timer, qemu_get_clock(vm_clock) + kvmppc_timer_rate);
 109 }
 110