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hw/i386/pc_sysfw: support two flash drives

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This patch allows the user to usefully specify

  -drive file=img_1,if=pflash,format=raw,readonly \
  -drive file=img_2,if=pflash,format=raw

on the command line. The flash images will be mapped under 4G in their
reverse unit order -- that is, with their base addresses progressing
downwards, in increasing unit order.

(The unit number increases with command line order if not explicitly
specified.)

This accommodates the following use case: suppose that OVMF is split in
two parts, a writeable host file for non-volatile variable storage, and a
read-only part for bootstrap and decompressible executable code.

The binary code part would be read-only, centrally managed on the host
system, and passed in as unit 0. The variable store would be writeable,
VM-specific, and passed in as unit 1.

  00000000ffe00000-00000000ffe1ffff (prio 0, R-): system.flash1
  00000000ffe20000-00000000ffffffff (prio 0, R-): system.flash0

(If the guest tries to write to the flash range that is backed by the
read-only drive, pflash_update() is never called; various flash
programming/erase errors are returned to the guest instead. See the
callers of pflash_update(), and the initialization of "pfl->ro", in
"hw/block/pflash_cfi01.c".)

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Laszlo Ersek 2013-11-28 00:52:52 +01:00 committed by Michael S. Tsirkin
parent ecdbfceb0f
commit 637a5acb46
1 changed files with 86 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

97
hw/i386/pc_sysfw.c
View File

@ -72,36 +72,103 @@ static void pc_isa_bios_init(MemoryRegion *rom_memory,
memory_region_set_readonly(isa_bios, true);
}
static void pc_system_flash_init(MemoryRegion *rom_memory,
DriveInfo *pflash_drv)
#define FLASH_MAP_UNIT_MAX 2
/* We don't have a theoretically justifiable exact lower bound on the base
* address of any flash mapping. In practice, the IO-APIC MMIO range is
* [0xFEE00000..0xFEE01000[ -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
* only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
* size.
*/
#define FLASH_MAP_BASE_MIN ((hwaddr)(0x100000000ULL - 8*1024*1024))
/* This function maps flash drives from 4G downward, in order of their unit
* numbers. The mapping starts at unit#0, with unit number increments of 1, and
* stops before the first missing flash drive, or before
* unit#FLASH_MAP_UNIT_MAX, whichever is reached first.
*
* Addressing within one flash drive is of course not reversed.
*
* An error message is printed and the process exits if:
* - the size of the backing file for a flash drive is non-positive, or not a
* multiple of the required sector size, or
* - the current mapping's base address would fall below FLASH_MAP_BASE_MIN.
*
* The drive with unit#0 (if available) is mapped at the highest address, and
* it is passed to pc_isa_bios_init(). Merging several drives for isa-bios is
* not supported.
*/
static void pc_system_flash_init(MemoryRegion *rom_memory)
{
int unit;
DriveInfo *pflash_drv;
BlockDriverState *bdrv;
int64_t size;
hwaddr phys_addr;
char *fatal_errmsg = NULL;
hwaddr phys_addr = 0x100000000ULL;
int sector_bits, sector_size;
pflash_t *system_flash;
MemoryRegion *flash_mem;
char name[64];
bdrv = pflash_drv->bdrv;
size = bdrv_getlength(pflash_drv->bdrv);
sector_bits = 12;
sector_size = 1 << sector_bits;
if ((size % sector_size) != 0) {
fprintf(stderr,
"qemu: PC system firmware (pflash) must be a multiple of 0x%x\n",
sector_size);
for (unit = 0;
(unit < FLASH_MAP_UNIT_MAX &&
(pflash_drv = drive_get(IF_PFLASH, 0, unit)) != NULL);
++unit) {
bdrv = pflash_drv->bdrv;
size = bdrv_getlength(bdrv);
if (size < 0) {
fatal_errmsg = g_strdup_printf("failed to get backing file size");
} else if (size == 0) {
fatal_errmsg = g_strdup_printf("PC system firmware (pflash) "
"cannot have zero size");
} else if ((size % sector_size) != 0) {
fatal_errmsg = g_strdup_printf("PC system firmware (pflash) "
"must be a multiple of 0x%x", sector_size);
} else if (phys_addr < size || phys_addr - size < FLASH_MAP_BASE_MIN) {
fatal_errmsg = g_strdup_printf("oversized backing file, pflash "
"segments cannot be mapped under "
TARGET_FMT_plx, FLASH_MAP_BASE_MIN);
}
if (fatal_errmsg != NULL) {
Location loc;
/* push a new, "none" location on the location stack; overwrite its
* contents with the location saved in the option; print the error
* (includes location); pop the top
*/
loc_push_none(&loc);
if (pflash_drv->opts != NULL) {
qemu_opts_loc_restore(pflash_drv->opts);
}
error_report("%s", fatal_errmsg);
loc_pop(&loc);
g_free(fatal_errmsg);
exit(1);
}
phys_addr = 0x100000000ULL - size;
system_flash = pflash_cfi01_register(phys_addr, NULL, "system.flash", size,
bdrv, sector_size, size >> sector_bits,
1, 0x0000, 0x0000, 0x0000, 0x0000, 0);
flash_mem = pflash_cfi01_get_memory(system_flash);
phys_addr -= size;
/* pflash_cfi01_register() creates a deep copy of the name */
snprintf(name, sizeof name, "system.flash%d", unit);
system_flash = pflash_cfi01_register(phys_addr, NULL /* qdev */, name,
size, bdrv, sector_size,
size >> sector_bits,
1 /* width */,
0x0000 /* id0 */,
0x0000 /* id1 */,
0x0000 /* id2 */,
0x0000 /* id3 */,
0 /* be */);
if (unit == 0) {
flash_mem = pflash_cfi01_get_memory(system_flash);
pc_isa_bios_init(rom_memory, flash_mem, size);
}
}
}
static void old_pc_system_rom_init(MemoryRegion *rom_memory, bool isapc_ram_fw)
{
@ -181,5 +248,5 @@ void pc_system_firmware_init(MemoryRegion *rom_memory, bool isapc_ram_fw)
exit(1);
}
pc_system_flash_init(rom_memory, pflash_drv);
pc_system_flash_init(rom_memory);
}