qemu/hw/char/spapr_vty.c
David Gibson 6c3bc244d3 spapr: Implement bug in spapr-vty device to be compatible with PowerVM
The spapr-vty device implements the PAPR defined virtual console,
which is also implemented by IBM's proprietary PowerVM hypervisor.

PowerVM's implementation has a bug where it inserts an extra \0 after
every \r going to the guest.  Because of that Linux's guest side
driver has a workaround which strips \0 characters that appear
immediately after a \r.

That means that when running under qemu, sending a binary stream from
host to guest via spapr-vty which happens to include a \r\0 sequence
will get corrupted by that workaround.

To deal with that, this patch duplicates PowerVM's bug, inserting an
extra \0 after each \r.  Ugly, but the best option available.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
2017-11-22 15:28:37 +11:00

278 lines
7.6 KiB
C

#include "qemu/osdep.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "cpu.h"
#include "hw/qdev.h"
#include "chardev/char-fe.h"
#include "hw/ppc/spapr.h"
#include "hw/ppc/spapr_vio.h"
#define VTERM_BUFSIZE 16
typedef struct VIOsPAPRVTYDevice {
VIOsPAPRDevice sdev;
CharBackend chardev;
uint32_t in, out;
uint8_t buf[VTERM_BUFSIZE];
} VIOsPAPRVTYDevice;
#define TYPE_VIO_SPAPR_VTY_DEVICE "spapr-vty"
#define VIO_SPAPR_VTY_DEVICE(obj) \
OBJECT_CHECK(VIOsPAPRVTYDevice, (obj), TYPE_VIO_SPAPR_VTY_DEVICE)
static int vty_can_receive(void *opaque)
{
VIOsPAPRVTYDevice *dev = VIO_SPAPR_VTY_DEVICE(opaque);
return VTERM_BUFSIZE - (dev->in - dev->out);
}
static void vty_receive(void *opaque, const uint8_t *buf, int size)
{
VIOsPAPRVTYDevice *dev = VIO_SPAPR_VTY_DEVICE(opaque);
int i;
if ((dev->in == dev->out) && size) {
/* toggle line to simulate edge interrupt */
qemu_irq_pulse(spapr_vio_qirq(&dev->sdev));
}
for (i = 0; i < size; i++) {
if (dev->in - dev->out >= VTERM_BUFSIZE) {
static bool reported;
if (!reported) {
error_report("VTY input buffer exhausted - characters dropped."
" (input size = %i)", size);
reported = true;
}
break;
}
dev->buf[dev->in++ % VTERM_BUFSIZE] = buf[i];
}
}
static int vty_getchars(VIOsPAPRDevice *sdev, uint8_t *buf, int max)
{
VIOsPAPRVTYDevice *dev = VIO_SPAPR_VTY_DEVICE(sdev);
int n = 0;
while ((n < max) && (dev->out != dev->in)) {
buf[n++] = dev->buf[dev->out++ % VTERM_BUFSIZE];
/* PowerVM's vty implementation has a bug where it inserts a
* \0 after every \r going to the guest. Existing guests have
* a workaround for this which removes every \0 immediately
* following a \r, so here we make ourselves bug-for-bug
* compatible, so that the guest won't drop a real \0-after-\r
* that happens to occur in a binary stream. */
if (buf[n - 1] == '\r') {
if (n < max) {
buf[n++] = '\0';
} else {
/* No room for the extra \0, roll back and try again
* next time */
dev->out--;
n--;
break;
}
}
}
qemu_chr_fe_accept_input(&dev->chardev);
return n;
}
void vty_putchars(VIOsPAPRDevice *sdev, uint8_t *buf, int len)
{
VIOsPAPRVTYDevice *dev = VIO_SPAPR_VTY_DEVICE(sdev);
/* XXX this blocks entire thread. Rewrite to use
* qemu_chr_fe_write and background I/O callbacks */
qemu_chr_fe_write_all(&dev->chardev, buf, len);
}
static void spapr_vty_realize(VIOsPAPRDevice *sdev, Error **errp)
{
VIOsPAPRVTYDevice *dev = VIO_SPAPR_VTY_DEVICE(sdev);
if (!qemu_chr_fe_backend_connected(&dev->chardev)) {
error_setg(errp, "chardev property not set");
return;
}
qemu_chr_fe_set_handlers(&dev->chardev, vty_can_receive,
vty_receive, NULL, NULL, dev, NULL, true);
}
/* Forward declaration */
static target_ulong h_put_term_char(PowerPCCPU *cpu, sPAPRMachineState *spapr,
target_ulong opcode, target_ulong *args)
{
target_ulong reg = args[0];
target_ulong len = args[1];
target_ulong char0_7 = args[2];
target_ulong char8_15 = args[3];
VIOsPAPRDevice *sdev;
uint8_t buf[16];
sdev = vty_lookup(spapr, reg);
if (!sdev) {
return H_PARAMETER;
}
if (len > 16) {
return H_PARAMETER;
}
*((uint64_t *)buf) = cpu_to_be64(char0_7);
*((uint64_t *)buf + 1) = cpu_to_be64(char8_15);
vty_putchars(sdev, buf, len);
return H_SUCCESS;
}
static target_ulong h_get_term_char(PowerPCCPU *cpu, sPAPRMachineState *spapr,
target_ulong opcode, target_ulong *args)
{
target_ulong reg = args[0];
target_ulong *len = args + 0;
target_ulong *char0_7 = args + 1;
target_ulong *char8_15 = args + 2;
VIOsPAPRDevice *sdev;
uint8_t buf[16];
sdev = vty_lookup(spapr, reg);
if (!sdev) {
return H_PARAMETER;
}
*len = vty_getchars(sdev, buf, sizeof(buf));
if (*len < 16) {
memset(buf + *len, 0, 16 - *len);
}
*char0_7 = be64_to_cpu(*((uint64_t *)buf));
*char8_15 = be64_to_cpu(*((uint64_t *)buf + 1));
return H_SUCCESS;
}
void spapr_vty_create(VIOsPAPRBus *bus, Chardev *chardev)
{
DeviceState *dev;
dev = qdev_create(&bus->bus, "spapr-vty");
qdev_prop_set_chr(dev, "chardev", chardev);
qdev_init_nofail(dev);
}
static Property spapr_vty_properties[] = {
DEFINE_SPAPR_PROPERTIES(VIOsPAPRVTYDevice, sdev),
DEFINE_PROP_CHR("chardev", VIOsPAPRVTYDevice, chardev),
DEFINE_PROP_END_OF_LIST(),
};
static const VMStateDescription vmstate_spapr_vty = {
.name = "spapr_vty",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_SPAPR_VIO(sdev, VIOsPAPRVTYDevice),
VMSTATE_UINT32(in, VIOsPAPRVTYDevice),
VMSTATE_UINT32(out, VIOsPAPRVTYDevice),
VMSTATE_BUFFER(buf, VIOsPAPRVTYDevice),
VMSTATE_END_OF_LIST()
},
};
static void spapr_vty_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VIOsPAPRDeviceClass *k = VIO_SPAPR_DEVICE_CLASS(klass);
k->realize = spapr_vty_realize;
k->dt_name = "vty";
k->dt_type = "serial";
k->dt_compatible = "hvterm1";
set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
dc->props = spapr_vty_properties;
dc->vmsd = &vmstate_spapr_vty;
}
static const TypeInfo spapr_vty_info = {
.name = TYPE_VIO_SPAPR_VTY_DEVICE,
.parent = TYPE_VIO_SPAPR_DEVICE,
.instance_size = sizeof(VIOsPAPRVTYDevice),
.class_init = spapr_vty_class_init,
};
VIOsPAPRDevice *spapr_vty_get_default(VIOsPAPRBus *bus)
{
VIOsPAPRDevice *sdev, *selected;
BusChild *kid;
/*
* To avoid the console bouncing around we want one VTY to be
* the "default". We haven't really got anything to go on, so
* arbitrarily choose the one with the lowest reg value.
*/
selected = NULL;
QTAILQ_FOREACH(kid, &bus->bus.children, sibling) {
DeviceState *iter = kid->child;
/* Only look at VTY devices */
if (!object_dynamic_cast(OBJECT(iter), TYPE_VIO_SPAPR_VTY_DEVICE)) {
continue;
}
sdev = VIO_SPAPR_DEVICE(iter);
/* First VTY we've found, so it is selected for now */
if (!selected) {
selected = sdev;
continue;
}
/* Choose VTY with lowest reg value */
if (sdev->reg < selected->reg) {
selected = sdev;
}
}
return selected;
}
VIOsPAPRDevice *vty_lookup(sPAPRMachineState *spapr, target_ulong reg)
{
VIOsPAPRDevice *sdev;
sdev = spapr_vio_find_by_reg(spapr->vio_bus, reg);
if (!sdev && reg == 0) {
/* Hack for kernel early debug, which always specifies reg==0.
* We search all VIO devices, and grab the vty with the lowest
* reg. This attempts to mimic existing PowerVM behaviour
* (early debug does work there, despite having no vty with
* reg==0. */
return spapr_vty_get_default(spapr->vio_bus);
}
if (!object_dynamic_cast(OBJECT(sdev), TYPE_VIO_SPAPR_VTY_DEVICE)) {
return NULL;
}
return sdev;
}
static void spapr_vty_register_types(void)
{
spapr_register_hypercall(H_PUT_TERM_CHAR, h_put_term_char);
spapr_register_hypercall(H_GET_TERM_CHAR, h_get_term_char);
type_register_static(&spapr_vty_info);
}
type_init(spapr_vty_register_types)