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* PowerPC KVM support
* Copyright IBM Corp. 2008
* Authors:
* Hollis Blanchard <>
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
#include "qemu-common.h"
#include "qemu-timer.h"
#include "kvm_ppc.h"
#include "device_tree.h"
#define PROC_DEVTREE_PATH "/proc/device-tree"
static QEMUTimer *kvmppc_timer;
static unsigned int kvmppc_timer_rate;
int kvmppc_read_host_property(const char *node_path, const char *prop,
void *val, size_t len)
char *path;
FILE *f;
int ret = 0;
int pathlen;
pathlen = snprintf(NULL, 0, "%s/%s/%s", PROC_DEVTREE_PATH, node_path, prop)
+ 1;
path = qemu_malloc(pathlen);
snprintf(path, pathlen, "%s/%s/%s", PROC_DEVTREE_PATH, node_path, prop);
f = fopen(path, "rb");
if (f == NULL) {
ret = errno;
goto free;
len = fread(val, len, 1, f);
if (len != 1) {
ret = ferror(f);
goto close;
return ret;
static int kvmppc_copy_host_cell(void *fdt, const char *node, const char *prop)
uint32_t cell;
int ret;
ret = kvmppc_read_host_property(node, prop, &cell, sizeof(cell));
if (ret < 0) {
fprintf(stderr, "couldn't read host %s/%s\n", node, prop);
goto out;
ret = qemu_devtree_setprop_cell(fdt, node, prop, cell);
if (ret < 0) {
fprintf(stderr, "couldn't set guest %s/%s\n", node, prop);
goto out;
return ret;
void kvmppc_fdt_update(void *fdt)
/* Copy data from the host device tree into the guest. Since the guest can
* directly access the timebase without host involvement, we must expose
* the correct frequencies. */
kvmppc_copy_host_cell(fdt, "/cpus/cpu@0", "clock-frequency");
kvmppc_copy_host_cell(fdt, "/cpus/cpu@0", "timebase-frequency");
static void kvmppc_timer_hack(void *opaque)
qemu_mod_timer(kvmppc_timer, qemu_get_clock(vm_clock) + kvmppc_timer_rate);
void kvmppc_init(void)
/* XXX The only reason KVM yields control back to qemu is device IO. Since
* an idle guest does no IO, qemu's device model will never get a chance to
* run. So, until Qemu gains IO threads, we create this timer to ensure
* that the device model gets a chance to run. */
kvmppc_timer_rate = get_ticks_per_sec() / 10;
kvmppc_timer = qemu_new_timer(vm_clock, &kvmppc_timer_hack, NULL);
qemu_mod_timer(kvmppc_timer, qemu_get_clock(vm_clock) + kvmppc_timer_rate);
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