xref: /illumos-kvm-cmd/target-ppc/kvm_ppc.c (revision 68396ea9)
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
kvmppc_read_host_property(const char * node_path,const char * prop,void * val,size_t len)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 = qemu_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 
kvmppc_copy_host_cell(void * fdt,const char * node,const char * prop)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 
kvmppc_fdt_update(void * fdt)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 
kvmppc_timer_hack(void * opaque)89 static void kvmppc_timer_hack(void *opaque)
90 {
91     qemu_service_io();
92     qemu_mod_timer(kvmppc_timer, qemu_get_clock(vm_clock) + kvmppc_timer_rate);
93 }
94 
kvmppc_init(void)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(vm_clock, &kvmppc_timer_hack, NULL);
103     qemu_mod_timer(kvmppc_timer, qemu_get_clock(vm_clock) + kvmppc_timer_rate);
104 }
105 
106