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