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qemu/hw/block/swim.c
Kevin Wolf 86b1cf3227 block: Separate blk_is_writable() and blk_supports_write_perm() 
Currently, blk_is_read_only() tells whether a given BlockBackend can
only be used in read-only mode because its root node is read-only. Some
callers actually try to answer a slightly different question: Is the
BlockBackend configured to be writable, by taking write permissions on
the root node?

This can differ, for example, for CD-ROM devices which don't take write
permissions, but may be backed by a writable image file. scsi-cd allows
write requests to the drive if blk_is_read_only() returns false.
However, the write request will immediately run into an assertion
failure because the write permission is missing.

This patch introduces separate functions for both questions.
blk_supports_write_perm() answers the question whether the block
node/image file can support writable devices, whereas blk_is_writable()
tells whether the BlockBackend is currently configured to be writable.

All calls of blk_is_read_only() are converted to one of the two new
functions.

Fixes: https://bugs.launchpad.net/bugs/1906693
Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210118123448.307825-2-kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2021-01-27 20:45:20 +01:00

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/*
* QEMU Macintosh floppy disk controller emulator (SWIM)
*
* Copyright (c) 2014-2018 Laurent Vivier <laurent@vivier.eu>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
* Only the basic support: it allows to switch from IWM (Integrated WOZ
* Machine) mode to the SWIM mode and makes the linux driver happy.
*/
#include "qemu/osdep.h"
#include "qemu/main-loop.h"
#include "qapi/error.h"
#include "sysemu/block-backend.h"
#include "hw/sysbus.h"
#include "migration/vmstate.h"
#include "hw/block/block.h"
#include "hw/block/swim.h"
#include "hw/qdev-properties.h"
/* IWM registers */
#define IWM_PH0L 0
#define IWM_PH0H 1
#define IWM_PH1L 2
#define IWM_PH1H 3
#define IWM_PH2L 4
#define IWM_PH2H 5
#define IWM_PH3L 6
#define IWM_PH3H 7
#define IWM_MTROFF 8
#define IWM_MTRON 9
#define IWM_INTDRIVE 10
#define IWM_EXTDRIVE 11
#define IWM_Q6L 12
#define IWM_Q6H 13
#define IWM_Q7L 14
#define IWM_Q7H 15
/* SWIM registers */
#define SWIM_WRITE_DATA 0
#define SWIM_WRITE_MARK 1
#define SWIM_WRITE_CRC 2
#define SWIM_WRITE_PARAMETER 3
#define SWIM_WRITE_PHASE 4
#define SWIM_WRITE_SETUP 5
#define SWIM_WRITE_MODE0 6
#define SWIM_WRITE_MODE1 7
#define SWIM_READ_DATA 8
#define SWIM_READ_MARK 9
#define SWIM_READ_ERROR 10
#define SWIM_READ_PARAMETER 11
#define SWIM_READ_PHASE 12
#define SWIM_READ_SETUP 13
#define SWIM_READ_STATUS 14
#define SWIM_READ_HANDSHAKE 15
#define REG_SHIFT 9
#define SWIM_MODE_IWM 0
#define SWIM_MODE_SWIM 1
/* bits in phase register */
#define SWIM_SEEK_NEGATIVE 0x074
#define SWIM_STEP 0x071
#define SWIM_MOTOR_ON 0x072
#define SWIM_MOTOR_OFF 0x076
#define SWIM_INDEX 0x073
#define SWIM_EJECT 0x077
#define SWIM_SETMFM 0x171
#define SWIM_SETGCR 0x175
#define SWIM_RELAX 0x033
#define SWIM_LSTRB 0x008
#define SWIM_CA_MASK 0x077
/* Select values for swim_select and swim_readbit */
#define SWIM_READ_DATA_0 0x074
#define SWIM_TWOMEG_DRIVE 0x075
#define SWIM_SINGLE_SIDED 0x076
#define SWIM_DRIVE_PRESENT 0x077
#define SWIM_DISK_IN 0x170
#define SWIM_WRITE_PROT 0x171
#define SWIM_TRACK_ZERO 0x172
#define SWIM_TACHO 0x173
#define SWIM_READ_DATA_1 0x174
#define SWIM_MFM_MODE 0x175
#define SWIM_SEEK_COMPLETE 0x176
#define SWIM_ONEMEG_MEDIA 0x177
/* Bits in handshake register */
#define SWIM_MARK_BYTE 0x01
#define SWIM_CRC_ZERO 0x02
#define SWIM_RDDATA 0x04
#define SWIM_SENSE 0x08
#define SWIM_MOTEN 0x10
#define SWIM_ERROR 0x20
#define SWIM_DAT2BYTE 0x40
#define SWIM_DAT1BYTE 0x80
/* bits in setup register */
#define SWIM_S_INV_WDATA 0x01
#define SWIM_S_3_5_SELECT 0x02
#define SWIM_S_GCR 0x04
#define SWIM_S_FCLK_DIV2 0x08
#define SWIM_S_ERROR_CORR 0x10
#define SWIM_S_IBM_DRIVE 0x20
#define SWIM_S_GCR_WRITE 0x40
#define SWIM_S_TIMEOUT 0x80
/* bits in mode register */
#define SWIM_CLFIFO 0x01
#define SWIM_ENBL1 0x02
#define SWIM_ENBL2 0x04
#define SWIM_ACTION 0x08
#define SWIM_WRITE_MODE 0x10
#define SWIM_HEDSEL 0x20
#define SWIM_MOTON 0x80
static void fd_recalibrate(FDrive *drive)
{
}
static void swim_change_cb(void *opaque, bool load, Error **errp)
{
FDrive *drive = opaque;
if (!load) {
blk_set_perm(drive->blk, 0, BLK_PERM_ALL, &error_abort);
} else {
if (!blkconf_apply_backend_options(drive->conf,
!blk_supports_write_perm(drive->blk),
false, errp)) {
return;
}
}
}
static const BlockDevOps swim_block_ops = {
.change_media_cb = swim_change_cb,
};
static Property swim_drive_properties[] = {
DEFINE_PROP_INT32("unit", SWIMDrive, unit, -1),
DEFINE_BLOCK_PROPERTIES(SWIMDrive, conf),
DEFINE_PROP_END_OF_LIST(),
};
static void swim_drive_realize(DeviceState *qdev, Error **errp)
{
SWIMDrive *dev = SWIM_DRIVE(qdev);
SWIMBus *bus = SWIM_BUS(qdev->parent_bus);
FDrive *drive;
int ret;
if (dev->unit == -1) {
for (dev->unit = 0; dev->unit < SWIM_MAX_FD; dev->unit++) {
drive = &bus->ctrl->drives[dev->unit];
if (!drive->blk) {
break;
}
}
}
if (dev->unit >= SWIM_MAX_FD) {
error_setg(errp, "Can't create floppy unit %d, bus supports "
"only %d units", dev->unit, SWIM_MAX_FD);
return;
}
drive = &bus->ctrl->drives[dev->unit];
if (drive->blk) {
error_setg(errp, "Floppy unit %d is in use", dev->unit);
return;
}
if (!dev->conf.blk) {
/* Anonymous BlockBackend for an empty drive */
dev->conf.blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
ret = blk_attach_dev(dev->conf.blk, qdev);
assert(ret == 0);
}
if (!blkconf_blocksizes(&dev->conf, errp)) {
return;
}
if (dev->conf.logical_block_size != 512 ||
dev->conf.physical_block_size != 512)
{
error_setg(errp, "Physical and logical block size must "
"be 512 for floppy");
return;
}
/*
* rerror/werror aren't supported by fdc and therefore not even registered
* with qdev. So set the defaults manually before they are used in
* blkconf_apply_backend_options().
*/
dev->conf.rerror = BLOCKDEV_ON_ERROR_AUTO;
dev->conf.werror = BLOCKDEV_ON_ERROR_AUTO;
if (!blkconf_apply_backend_options(&dev->conf,
!blk_supports_write_perm(dev->conf.blk),
false, errp)) {
return;
}
/*
* 'enospc' is the default for -drive, 'report' is what blk_new() gives us
* for empty drives.
*/
if (blk_get_on_error(dev->conf.blk, 0) != BLOCKDEV_ON_ERROR_ENOSPC &&
blk_get_on_error(dev->conf.blk, 0) != BLOCKDEV_ON_ERROR_REPORT) {
error_setg(errp, "fdc doesn't support drive option werror");
return;
}
if (blk_get_on_error(dev->conf.blk, 1) != BLOCKDEV_ON_ERROR_REPORT) {
error_setg(errp, "fdc doesn't support drive option rerror");
return;
}
drive->conf = &dev->conf;
drive->blk = dev->conf.blk;
drive->swimctrl = bus->ctrl;
blk_set_dev_ops(drive->blk, &swim_block_ops, drive);
}
static void swim_drive_class_init(ObjectClass *klass, void *data)
{
DeviceClass *k = DEVICE_CLASS(klass);
k->realize = swim_drive_realize;
set_bit(DEVICE_CATEGORY_STORAGE, k->categories);
k->bus_type = TYPE_SWIM_BUS;
device_class_set_props(k, swim_drive_properties);
k->desc = "virtual SWIM drive";
}
static const TypeInfo swim_drive_info = {
.name = TYPE_SWIM_DRIVE,
.parent = TYPE_DEVICE,
.instance_size = sizeof(SWIMDrive),
.class_init = swim_drive_class_init,
};
static const TypeInfo swim_bus_info = {
.name = TYPE_SWIM_BUS,
.parent = TYPE_BUS,
.instance_size = sizeof(SWIMBus),
};
static void iwmctrl_write(void *opaque, hwaddr reg, uint64_t value,
unsigned size)
{
SWIMCtrl *swimctrl = opaque;
reg >>= REG_SHIFT;
swimctrl->regs[reg >> 1] = reg & 1;
if (swimctrl->regs[IWM_Q6] &&
swimctrl->regs[IWM_Q7]) {
if (swimctrl->regs[IWM_MTR]) {
/* data register */
swimctrl->iwm_data = value;
} else {
/* mode register */
swimctrl->iwm_mode = value;
/* detect sequence to switch from IWM mode to SWIM mode */
switch (swimctrl->iwm_switch) {
case 0:
if (value == 0x57) {
swimctrl->iwm_switch++;
}
break;
case 1:
if (value == 0x17) {
swimctrl->iwm_switch++;
}
break;
case 2:
if (value == 0x57) {
swimctrl->iwm_switch++;
}
break;
case 3:
if (value == 0x57) {
swimctrl->mode = SWIM_MODE_SWIM;
swimctrl->iwm_switch = 0;
}
break;
}
}
}
}
static uint64_t iwmctrl_read(void *opaque, hwaddr reg, unsigned size)
{
SWIMCtrl *swimctrl = opaque;
reg >>= REG_SHIFT;
swimctrl->regs[reg >> 1] = reg & 1;
return 0;
}
static void swimctrl_write(void *opaque, hwaddr reg, uint64_t value,
unsigned size)
{
SWIMCtrl *swimctrl = opaque;
if (swimctrl->mode == SWIM_MODE_IWM) {
iwmctrl_write(opaque, reg, value, size);
return;
}
reg >>= REG_SHIFT;
switch (reg) {
case SWIM_WRITE_PHASE:
swimctrl->swim_phase = value;
break;
case SWIM_WRITE_MODE0:
swimctrl->swim_mode &= ~value;
break;
case SWIM_WRITE_MODE1:
swimctrl->swim_mode |= value;
break;
case SWIM_WRITE_DATA:
case SWIM_WRITE_MARK:
case SWIM_WRITE_CRC:
case SWIM_WRITE_PARAMETER:
case SWIM_WRITE_SETUP:
break;
}
}
static uint64_t swimctrl_read(void *opaque, hwaddr reg, unsigned size)
{
SWIMCtrl *swimctrl = opaque;
uint32_t value = 0;
if (swimctrl->mode == SWIM_MODE_IWM) {
return iwmctrl_read(opaque, reg, size);
}
reg >>= REG_SHIFT;
switch (reg) {
case SWIM_READ_PHASE:
value = swimctrl->swim_phase;
break;
case SWIM_READ_HANDSHAKE:
if (swimctrl->swim_phase == SWIM_DRIVE_PRESENT) {
/* always answer "no drive present" */
value = SWIM_SENSE;
}
break;
case SWIM_READ_DATA:
case SWIM_READ_MARK:
case SWIM_READ_ERROR:
case SWIM_READ_PARAMETER:
case SWIM_READ_SETUP:
case SWIM_READ_STATUS:
break;
}
return value;
}
static const MemoryRegionOps swimctrl_mem_ops = {
.write = swimctrl_write,
.read = swimctrl_read,
.endianness = DEVICE_NATIVE_ENDIAN,
};
static void sysbus_swim_reset(DeviceState *d)
{
Swim *sys = SWIM(d);
SWIMCtrl *ctrl = &sys->ctrl;
int i;
ctrl->mode = 0;
ctrl->iwm_switch = 0;
for (i = 0; i < 8; i++) {
ctrl->regs[i] = 0;
}
ctrl->iwm_data = 0;
ctrl->iwm_mode = 0;
ctrl->swim_phase = 0;
ctrl->swim_mode = 0;
for (i = 0; i < SWIM_MAX_FD; i++) {
fd_recalibrate(&ctrl->drives[i]);
}
}
static void sysbus_swim_init(Object *obj)
{
SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
Swim *sbs = SWIM(obj);
SWIMCtrl *swimctrl = &sbs->ctrl;
memory_region_init_io(&swimctrl->iomem, obj, &swimctrl_mem_ops, swimctrl,
"swim", 0x2000);
sysbus_init_mmio(sbd, &swimctrl->iomem);
}
static void sysbus_swim_realize(DeviceState *dev, Error **errp)
{
Swim *sys = SWIM(dev);
SWIMCtrl *swimctrl = &sys->ctrl;
qbus_create_inplace(&swimctrl->bus, sizeof(SWIMBus), TYPE_SWIM_BUS, dev,
NULL);
swimctrl->bus.ctrl = swimctrl;
}
static const VMStateDescription vmstate_fdrive = {
.name = "fdrive",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_END_OF_LIST()
},
};
static const VMStateDescription vmstate_swim = {
.name = "swim",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_INT32(mode, SWIMCtrl),
/* IWM mode */
VMSTATE_INT32(iwm_switch, SWIMCtrl),
VMSTATE_UINT16_ARRAY(regs, SWIMCtrl, 8),
VMSTATE_UINT8(iwm_data, SWIMCtrl),
VMSTATE_UINT8(iwm_mode, SWIMCtrl),
/* SWIM mode */
VMSTATE_UINT8(swim_phase, SWIMCtrl),
VMSTATE_UINT8(swim_mode, SWIMCtrl),
/* Drives */
VMSTATE_STRUCT_ARRAY(drives, SWIMCtrl, SWIM_MAX_FD, 1,
vmstate_fdrive, FDrive),
VMSTATE_END_OF_LIST()
},
};
static const VMStateDescription vmstate_sysbus_swim = {
.name = "SWIM",
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_STRUCT(ctrl, Swim, 0, vmstate_swim, SWIMCtrl),
VMSTATE_END_OF_LIST()
}
};
static void sysbus_swim_class_init(ObjectClass *oc, void *data)
{
DeviceClass *dc = DEVICE_CLASS(oc);
dc->realize = sysbus_swim_realize;
dc->reset = sysbus_swim_reset;
dc->vmsd = &vmstate_sysbus_swim;
}
static const TypeInfo sysbus_swim_info = {
.name = TYPE_SWIM,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(Swim),
.instance_init = sysbus_swim_init,
.class_init = sysbus_swim_class_init,
};
static void swim_register_types(void)
{
type_register_static(&sysbus_swim_info);
type_register_static(&swim_bus_info);
type_register_static(&swim_drive_info);
}
type_init(swim_register_types)
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