qemu-e2k/hw/block/pc_sysfw.c
Markus Armbruster 9953f8822c pc: Kill the "use flash device for BIOS unless KVM" misfeature
Use of a flash memory device for the BIOS was added in series "[PATCH
v10 0/8] PC system flash support", commit 4732dca..1b89faf, v1.1.

Flash vs. ROM is a guest-visible difference.  Thus, flash use had to
be suppressed for machine types pc-1.0 and older.  This was
accomplished by adding a dummy device "pc-sysfw" with property
"rom_only":

* Non-zero rom_only means "use ROM".  Default for pc-1.0 and older.
* Zero rom_only means "maybe use flash".  Default for newer machines.

Not only is the dummy device ugly, it was also retroactively added to
the older machine types!  Fortunately, it's not guest-visible (thus no
immediate guest ABI breakage), and has no vmstate (thus no immediate
migration breakage).  Breakage occurs only if the user unwisely
enables flash by setting rom_only to zero.  Patch review FAIL #1.

Why "maybe use flash"?  Flash didn't (and still doesn't) work with
KVM.  Therefore, rom_only=0 really means "use flash, except when KVM
is enabled, use ROM".  This is a Bad Idea, because it makes enabling/
disabling KVM guest-visible.  Patch review FAIL #2.

Aside: it also precludes migrating between KVM on and off, but that's
not possible for other reasons anyway.

Fix as follows:

1. Change the meaning of rom_only=0 to mean "use flash, no ifs, buts,
or maybes" for pc-i440fx-1.5 and pc-q35-1.5.  Don't change anything
for older machines (to remain bug-compatible).

2. Change the default value from 0 to 1 for these machines.
Necessary, because 0 doesn't work with KVM.  Once it does, we can flip
the default back to 0.

3. Don't revert the retroactive addition of device "pc-sysfw" to older
machine types.  Seems not worth the trouble.

4. Add a TODO comment asking for device "pc-sysfw" to be dropped once
flash works with KVM.

Net effect is that you get a BIOS ROM again even when KVM is disabled,
just like for machines predating the introduction of flash.

To get flash instead, use "--global pc-sysfw.rom_only=0".

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1365780303-26398-4-git-send-email-armbru@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-04-24 13:23:51 -05:00

290 lines
8.5 KiB
C

/*
* QEMU PC System Firmware
*
* Copyright (c) 2003-2004 Fabrice Bellard
* Copyright (c) 2011-2012 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "sysemu/blockdev.h"
#include "qemu/error-report.h"
#include "hw/sysbus.h"
#include "hw/hw.h"
#include "hw/i386/pc.h"
#include "hw/boards.h"
#include "hw/loader.h"
#include "sysemu/sysemu.h"
#include "hw/block/flash.h"
#include "sysemu/kvm.h"
#define BIOS_FILENAME "bios.bin"
typedef struct PcSysFwDevice {
SysBusDevice busdev;
uint8_t rom_only;
} PcSysFwDevice;
static void pc_isa_bios_init(MemoryRegion *rom_memory,
MemoryRegion *flash_mem,
int ram_size)
{
int isa_bios_size;
MemoryRegion *isa_bios;
uint64_t flash_size;
void *flash_ptr, *isa_bios_ptr;
flash_size = memory_region_size(flash_mem);
/* map the last 128KB of the BIOS in ISA space */
isa_bios_size = flash_size;
if (isa_bios_size > (128 * 1024)) {
isa_bios_size = 128 * 1024;
}
isa_bios = g_malloc(sizeof(*isa_bios));
memory_region_init_ram(isa_bios, "isa-bios", isa_bios_size);
vmstate_register_ram_global(isa_bios);
memory_region_add_subregion_overlap(rom_memory,
0x100000 - isa_bios_size,
isa_bios,
1);
/* copy ISA rom image from top of flash memory */
flash_ptr = memory_region_get_ram_ptr(flash_mem);
isa_bios_ptr = memory_region_get_ram_ptr(isa_bios);
memcpy(isa_bios_ptr,
((uint8_t*)flash_ptr) + (flash_size - isa_bios_size),
isa_bios_size);
memory_region_set_readonly(isa_bios, true);
}
static void pc_fw_add_pflash_drv(void)
{
QemuOpts *opts;
QEMUMachine *machine;
char *filename;
if (bios_name == NULL) {
bios_name = BIOS_FILENAME;
}
filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
if (!filename) {
error_report("Can't open BIOS image %s", bios_name);
exit(1);
}
opts = drive_add(IF_PFLASH, -1, filename, "readonly=on");
g_free(filename);
if (opts == NULL) {
return;
}
machine = find_default_machine();
if (machine == NULL) {
return;
}
if (!drive_init(opts, machine->block_default_type)) {
qemu_opts_del(opts);
}
}
static void pc_system_flash_init(MemoryRegion *rom_memory,
DriveInfo *pflash_drv)
{
BlockDriverState *bdrv;
int64_t size;
hwaddr phys_addr;
int sector_bits, sector_size;
pflash_t *system_flash;
MemoryRegion *flash_mem;
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);
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);
pc_isa_bios_init(rom_memory, flash_mem, size);
}
static void old_pc_system_rom_init(MemoryRegion *rom_memory)
{
char *filename;
MemoryRegion *bios, *isa_bios;
int bios_size, isa_bios_size;
int ret;
/* BIOS load */
if (bios_name == NULL) {
bios_name = BIOS_FILENAME;
}
filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
if (filename) {
bios_size = get_image_size(filename);
} else {
bios_size = -1;
}
if (bios_size <= 0 ||
(bios_size % 65536) != 0) {
goto bios_error;
}
bios = g_malloc(sizeof(*bios));
memory_region_init_ram(bios, "pc.bios", bios_size);
vmstate_register_ram_global(bios);
memory_region_set_readonly(bios, true);
ret = rom_add_file_fixed(bios_name, (uint32_t)(-bios_size), -1);
if (ret != 0) {
bios_error:
fprintf(stderr, "qemu: could not load PC BIOS '%s'\n", bios_name);
exit(1);
}
if (filename) {
g_free(filename);
}
/* map the last 128KB of the BIOS in ISA space */
isa_bios_size = bios_size;
if (isa_bios_size > (128 * 1024)) {
isa_bios_size = 128 * 1024;
}
isa_bios = g_malloc(sizeof(*isa_bios));
memory_region_init_alias(isa_bios, "isa-bios", bios,
bios_size - isa_bios_size, isa_bios_size);
memory_region_add_subregion_overlap(rom_memory,
0x100000 - isa_bios_size,
isa_bios,
1);
memory_region_set_readonly(isa_bios, true);
/* map all the bios at the top of memory */
memory_region_add_subregion(rom_memory,
(uint32_t)(-bios_size),
bios);
}
/*
* Bug-compatible flash vs. ROM selection enabled?
* A few older machines enable this.
*/
bool pc_sysfw_flash_vs_rom_bug_compatible;
void pc_system_firmware_init(MemoryRegion *rom_memory)
{
DriveInfo *pflash_drv;
PcSysFwDevice *sysfw_dev;
/*
* TODO This device exists only so that users can switch between
* use of flash and ROM for the BIOS. The ability to switch was
* created because flash doesn't work with KVM. Once it does, we
* should drop this device for new machine types.
*/
sysfw_dev = (PcSysFwDevice*) qdev_create(NULL, "pc-sysfw");
qdev_init_nofail(DEVICE(sysfw_dev));
if (sysfw_dev->rom_only) {
old_pc_system_rom_init(rom_memory);
return;
}
pflash_drv = drive_get(IF_PFLASH, 0, 0);
/* Currently KVM cannot execute from device memory.
Use old rom based firmware initialization for KVM. */
/*
* This is a Bad Idea, because it makes enabling/disabling KVM
* guest-visible. Do it only in bug-compatibility mode.
*/
if (pc_sysfw_flash_vs_rom_bug_compatible && kvm_enabled()) {
if (pflash_drv != NULL) {
fprintf(stderr, "qemu: pflash cannot be used with kvm enabled\n");
exit(1);
} else {
sysfw_dev->rom_only = 1;
old_pc_system_rom_init(rom_memory);
return;
}
}
/* If a pflash drive is not found, then create one using
the bios filename. */
if (pflash_drv == NULL) {
pc_fw_add_pflash_drv();
pflash_drv = drive_get(IF_PFLASH, 0, 0);
}
if (pflash_drv != NULL) {
pc_system_flash_init(rom_memory, pflash_drv);
} else {
fprintf(stderr, "qemu: PC system firmware (pflash) not available\n");
exit(1);
}
}
static Property pcsysfw_properties[] = {
DEFINE_PROP_UINT8("rom_only", PcSysFwDevice, rom_only, 1),
DEFINE_PROP_END_OF_LIST(),
};
static int pcsysfw_init(DeviceState *dev)
{
return 0;
}
static void pcsysfw_class_init (ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS (klass);
dc->desc = "PC System Firmware";
dc->init = pcsysfw_init;
dc->props = pcsysfw_properties;
}
static const TypeInfo pcsysfw_info = {
.name = "pc-sysfw",
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof (PcSysFwDevice),
.class_init = pcsysfw_class_init,
};
static void pcsysfw_register (void)
{
type_register_static (&pcsysfw_info);
}
type_init (pcsysfw_register);