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fw-cfg: turn FW_CFG_FILE_SLOTS into a device property 

We'd like to raise the value of FW_CFG_FILE_SLOTS. Doing it naively could
lead to problems with backward migration: a more recent QEMU (running an
older machine type) would allow the guest, in fw_cfg_select(), to select a
high key value that is unavailable in the same machine type implemented by
the older (target) QEMU. On the target host, fw_cfg_data_read() for
example could dereference nonexistent entries.

As first step, size the FWCfgState.entries[*] and FWCfgState.entry_order
arrays dynamically. All three array sizes will be influenced by the new
field FWCfgState.file_slots (and matching device property).

Make the following changes:

- Replace the FW_CFG_FILE_SLOTS macro with FW_CFG_FILE_SLOTS_MIN (minimum
  count of fw_cfg file slots) in the header file. The value remains 0x10.

- Replace all uses of FW_CFG_FILE_SLOTS with a helper function called
  fw_cfg_file_slots(), returning the new property.

- Eliminate the macro FW_CFG_MAX_ENTRY, and replace all its uses with a
  helper function called fw_cfg_max_entry().

- In the MMIO- and IO-mapped realize functions both, allocate all three
  arrays dynamically, based on the new property.

- The new property defaults to FW_CFG_FILE_SLOTS_MIN. This is going to be
  customized in the following patches.

Cc: "Gabriel L. Somlo" <somlo@cmu.edu>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Gabriel Somlo <somlo@cmu.edu>
Tested-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Laszlo Ersek 2017-01-12 19:24:15 +01:00 committed by Michael S. Tsirkin
parent baf2d5bfba
commit e12f3a13e2
3 changed files with 65 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
docs/specs/fw_cfg.txt
View File

@ -156,7 +156,7 @@ Selector Reg. Range Usage
0xc000 - 0xffff Arch. Specific (0x0000 - 0x3fff, RW, ignored in v2.4+)
In practice, the number of allowed firmware configuration items is given
by the value of FW_CFG_MAX_ENTRY (see fw_cfg.h).
by the value (FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS_MIN) (see fw_cfg.h).
= Guest-side DMA Interface =

71
hw/nvram/fw_cfg.c
View File

@ -33,6 +33,7 @@
#include "qemu/error-report.h"
#include "qemu/config-file.h"
#include "qemu/cutils.h"
#include "qapi/error.h"
#define FW_CFG_NAME "fw_cfg"
#define FW_CFG_PATH "/machine/" FW_CFG_NAME
@ -71,8 +72,9 @@ struct FWCfgState {
SysBusDevice parent_obj;
/*< public >*/
FWCfgEntry entries[2][FW_CFG_MAX_ENTRY];
int entry_order[FW_CFG_MAX_ENTRY];
uint16_t file_slots;
FWCfgEntry *entries[2];
int *entry_order;
FWCfgFiles *files;
uint16_t cur_entry;
uint32_t cur_offset;
@ -257,13 +259,24 @@ static void fw_cfg_write(FWCfgState *s, uint8_t value)
/* nothing, write support removed in QEMU v2.4+ */
}
static inline uint16_t fw_cfg_file_slots(const FWCfgState *s)
{
return s->file_slots;
}
/* Note: this function returns an exclusive limit. */
static inline uint32_t fw_cfg_max_entry(const FWCfgState *s)
{
return FW_CFG_FILE_FIRST + fw_cfg_file_slots(s);
}
static int fw_cfg_select(FWCfgState *s, uint16_t key)
{
int arch, ret;
FWCfgEntry *e;
s->cur_offset = 0;
if ((key & FW_CFG_ENTRY_MASK) >= FW_CFG_MAX_ENTRY) {
if ((key & FW_CFG_ENTRY_MASK) >= fw_cfg_max_entry(s)) {
s->cur_entry = FW_CFG_INVALID;
ret = 0;
} else {
@ -610,7 +623,7 @@ static void fw_cfg_add_bytes_read_callback(FWCfgState *s, uint16_t key,
key &= FW_CFG_ENTRY_MASK;
assert(key < FW_CFG_MAX_ENTRY && len < UINT32_MAX);
assert(key < fw_cfg_max_entry(s) && len < UINT32_MAX);
assert(s->entries[arch][key].data == NULL); /* avoid key conflict */
s->entries[arch][key].data = data;
@ -628,7 +641,7 @@ static void *fw_cfg_modify_bytes_read(FWCfgState *s, uint16_t key,
key &= FW_CFG_ENTRY_MASK;
assert(key < FW_CFG_MAX_ENTRY && len < UINT32_MAX);
assert(key < fw_cfg_max_entry(s) && len < UINT32_MAX);
/* return the old data to the function caller, avoid memory leak */
ptr = s->entries[arch][key].data;
@ -777,13 +790,13 @@ void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
int order = 0;
if (!s->files) {
dsize = sizeof(uint32_t) + sizeof(FWCfgFile) * FW_CFG_FILE_SLOTS;
dsize = sizeof(uint32_t) + sizeof(FWCfgFile) * fw_cfg_file_slots(s);
s->files = g_malloc0(dsize);
fw_cfg_add_bytes(s, FW_CFG_FILE_DIR, s->files, dsize);
}
count = be32_to_cpu(s->files->count);
assert(count < FW_CFG_FILE_SLOTS);
assert(count < fw_cfg_file_slots(s));
/* Find the insertion point. */
if (mc->legacy_fw_cfg_order) {
@ -857,7 +870,7 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
assert(s->files);
index = be32_to_cpu(s->files->count);
assert(index < FW_CFG_FILE_SLOTS);
assert(index < fw_cfg_file_slots(s));
for (i = 0; i < index; i++) {
if (strcmp(filename, s->files->f[i].name) == 0) {
@ -1014,12 +1027,38 @@ static const TypeInfo fw_cfg_info = {
.class_init = fw_cfg_class_init,
};
static void fw_cfg_file_slots_allocate(FWCfgState *s, Error **errp)
{
uint16_t file_slots_max;
if (fw_cfg_file_slots(s) < FW_CFG_FILE_SLOTS_MIN) {
error_setg(errp, "\"file_slots\" must be at least 0x%x",
FW_CFG_FILE_SLOTS_MIN);
return;
}
/* (UINT16_MAX & FW_CFG_ENTRY_MASK) is the highest inclusive selector value
* that we permit. The actual (exclusive) value coming from the
* configuration is (FW_CFG_FILE_FIRST + fw_cfg_file_slots(s)). */
file_slots_max = (UINT16_MAX & FW_CFG_ENTRY_MASK) - FW_CFG_FILE_FIRST + 1;
if (fw_cfg_file_slots(s) > file_slots_max) {
error_setg(errp, "\"file_slots\" must not exceed 0x%" PRIx16,
file_slots_max);
return;
}
s->entries[0] = g_new0(FWCfgEntry, fw_cfg_max_entry(s));
s->entries[1] = g_new0(FWCfgEntry, fw_cfg_max_entry(s));
s->entry_order = g_new0(int, fw_cfg_max_entry(s));
}
static Property fw_cfg_io_properties[] = {
DEFINE_PROP_UINT32("iobase", FWCfgIoState, iobase, -1),
DEFINE_PROP_UINT32("dma_iobase", FWCfgIoState, dma_iobase, -1),
DEFINE_PROP_BOOL("dma_enabled", FWCfgIoState, parent_obj.dma_enabled,
true),
DEFINE_PROP_UINT16("x-file-slots", FWCfgIoState, parent_obj.file_slots,
FW_CFG_FILE_SLOTS_MIN),
DEFINE_PROP_END_OF_LIST(),
};
@ -1027,6 +1066,13 @@ static void fw_cfg_io_realize(DeviceState *dev, Error **errp)
{
FWCfgIoState *s = FW_CFG_IO(dev);
SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
Error *local_err = NULL;
fw_cfg_file_slots_allocate(FW_CFG(s), &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
/* when using port i/o, the 8-bit data register ALWAYS overlaps
* with half of the 16-bit control register. Hence, the total size
@ -1063,6 +1109,8 @@ static Property fw_cfg_mem_properties[] = {
DEFINE_PROP_UINT32("data_width", FWCfgMemState, data_width, -1),
DEFINE_PROP_BOOL("dma_enabled", FWCfgMemState, parent_obj.dma_enabled,
true),
DEFINE_PROP_UINT16("x-file-slots", FWCfgMemState, parent_obj.file_slots,
FW_CFG_FILE_SLOTS_MIN),
DEFINE_PROP_END_OF_LIST(),
};
@ -1071,6 +1119,13 @@ static void fw_cfg_mem_realize(DeviceState *dev, Error **errp)
FWCfgMemState *s = FW_CFG_MEM(dev);
SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
const MemoryRegionOps *data_ops = &fw_cfg_data_mem_ops;
Error *local_err = NULL;
fw_cfg_file_slots_allocate(FW_CFG(s), &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
memory_region_init_io(&s->ctl_iomem, OBJECT(s), &fw_cfg_ctl_mem_ops,
FW_CFG(s), "fwcfg.ctl", FW_CFG_CTL_SIZE);

3
include/hw/nvram/fw_cfg_keys.h
View File

@ -29,8 +29,7 @@
#define FW_CFG_FILE_DIR 0x19
#define FW_CFG_FILE_FIRST 0x20
#define FW_CFG_FILE_SLOTS 0x10
#define FW_CFG_MAX_ENTRY (FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS)
#define FW_CFG_FILE_SLOTS_MIN 0x10
#define FW_CFG_WRITE_CHANNEL 0x4000
#define FW_CFG_ARCH_LOCAL 0x8000