On Fri, 2 Oct 2026, [email protected] wrote:
From: Utkarsh Verma <[email protected]>
Extend the VOF client interface to support console I/O through the sPAPR VTY
device, which is needed by bootloaders such as GRUB during disk boot.
Add vof_read() to implement the OpenFirmware "read" client service, which was
previously missing.
Route the OF read and write services backed by vty_getchars() and vty_putchars()
Make vty_getchars() public similar to vty_putchars().
AI-used-for: code
Signed-off-by: Utkarsh Verma <[email protected]>
---
hw/char/spapr_vty.c | 2 +-
hw/ppc/spapr_vof.c | 2 +
hw/ppc/trace-events | 2 +
hw/ppc/vof.c | 84 ++++++++++++++++++++++++++++++++++++++
include/hw/ppc/spapr_vio.h | 1 +
5 files changed, 90 insertions(+), 1 deletion(-)
diff --git a/hw/char/spapr_vty.c b/hw/char/spapr_vty.c
index 1dd9fb155c..2c97e0e027 100644
--- a/hw/char/spapr_vty.c
+++ b/hw/char/spapr_vty.c
@@ -52,7 +52,7 @@ static void vty_receive(void *opaque, const uint8_t *buf, int
size)
}
}
-static int vty_getchars(SpaprVioDevice *sdev, uint8_t *buf, int max)
+int vty_getchars(SpaprVioDevice *sdev, uint8_t *buf, int max)
{
SpaprVioVty *dev = VIO_SPAPR_VTY_DEVICE(sdev);
int n = 0;
diff --git a/hw/ppc/spapr_vof.c b/hw/ppc/spapr_vof.c
index 78d5b7d5b5..3195c859a4 100644
--- a/hw/ppc/spapr_vof.c
+++ b/hw/ppc/spapr_vof.c
@@ -76,6 +76,8 @@ void spapr_vof_client_dt_finalize(SpaprMachineState *spapr,
void *fdt)
if (stdout_path) {
_FDT(vof_client_open_store(fdt, spapr->vof, "/chosen", "stdout",
stdout_path));
+ _FDT(vof_client_open_store(fdt, spapr->vof, "/chosen", "stdin",
+ stdout_path));
}
}
diff --git a/hw/ppc/trace-events b/hw/ppc/trace-events
index 1f125ce841..dbdcfada26 100644
--- a/hw/ppc/trace-events
+++ b/hw/ppc/trace-events
@@ -79,6 +79,7 @@ vof_error_unknown_method(const char *method) "\"%s\""
vof_error_unknown_ihandle_close(uint32_t ih) "ih=0x%x"
vof_error_unknown_path(const char *path) "\"%s\""
vof_error_write(uint32_t ih) "ih=0x%x"
+vof_error_read(uint32_t ih) "ih=0x%x"
vof_finddevice(const char *path, uint32_t ph) "\"%s\" => ph=0x%x"
vof_claim(uint32_t virt, uint32_t size, uint32_t align, uint32_t ret) "virt=0x%x
size=0x%x align=0x%x => 0x%x"
vof_release(uint32_t virt, uint32_t size, uint32_t ret) "virt=0x%x size=0x%x =>
0x%x"
@@ -92,6 +93,7 @@ vof_package_to_path(uint32_t ph, const char *tmp, int ret)
"ph=0x%x => %s len=%d
vof_instance_to_path(uint32_t ih, uint32_t ph, const char *tmp, int ret) "ih=0x%x
ph=0x%x => %s len=%d"
vof_instance_to_package(uint32_t ih, uint32_t ph) "ih=0x%x => ph=0x%x"
vof_write(uint32_t ih, unsigned cb, const char *msg) "ih=0x%x [%u] \"%s\""
+vof_read(uint32_t ih, unsigned cb, const char *msg) "ih=0x%x [%u] \"%s\""
vof_avail(uint64_t start, uint64_t end, uint64_t size) "0x%"PRIx64"..0x%"PRIx64"
size=0x%"PRIx64
vof_claimed(uint64_t start, uint64_t end, uint64_t size) "0x%"PRIx64"..0x%"PRIx64"
size=0x%"PRIx64
diff --git a/hw/ppc/vof.c b/hw/ppc/vof.c
index 9ad1aa7626..6f6d424347 100644
--- a/hw/ppc/vof.c
+++ b/hw/ppc/vof.c
@@ -9,6 +9,7 @@
* SPDX-License-Identifier: GPL-2.0-or-later
*/
+#include CONFIG_DEVICES /* CONFIG_PSERIES */
#include "qemu/osdep.h"
#include "qemu/ctype.h"
#include "qemu/timer.h"
@@ -23,6 +24,7 @@
#include "qom/qom-qobject.h"
#include "trace.h"
+#include "hw/ppc/spapr_vio.h"
#include <libfdt.h>
/*
@@ -45,6 +47,7 @@ typedef struct {
typedef struct {
char *path; /* the path used to open the instance */
uint32_t phandle;
+ void *vty;
} OfInstance;
static int readstr(hwaddr pa, char *buf, int size)
@@ -459,6 +462,28 @@ static uint32_t vof_do_open(void *fdt, Vof *vof, int
offset, const char *path)
++vof->of_instance_last;
inst->path = g_strdup(path);
+ inst->vty = NULL;
+
+#ifdef CONFIG_PSERIES
+ const char *node_name = fdt_get_name(fdt, offset, NULL);
+ if (node_name && strncmp(node_name, "vty", 3) == 0) {
+ uint8_t discard_buf[VOF_VTY_BUF_SIZE];
+ MachineState *ms = MACHINE(qdev_get_machine());
+ SpaprMachineState *spapr = SPAPR_MACHINE(ms);
+
+ if (spapr && spapr->vio_bus) {
+ inst->vty = spapr_vty_get_default(spapr->vio_bus);
+ if (inst->vty) {
+ /* Flush any stale data from the VTY input buffer */
+ while (vty_getchars(inst->vty, discard_buf,
+ sizeof(discard_buf)) > 0) {
+ /* discard */
+ }
+ }
+ }
+ }
+#endif
+
g_hash_table_insert(vof->of_instances,
GINT_TO_POINTER(vof->of_instance_last),
inst);
@@ -577,6 +602,23 @@ static uint32_t vof_write(Vof *vof, uint32_t ihandle,
uint32_t buf,
return PROM_ERROR;
}
+#ifdef CONFIG_PSERIES
+ if (inst->vty) {
+ uint32_t total_written = 0;
+
+ for ( ; len > 0; len -= cb) {
+ cb = MIN(len, sizeof(tmp));
+ if (VOF_MEM_READ(buf, tmp, cb) != MEMTX_OK) {
+ return PROM_ERROR;
+ }
+ vty_putchars(inst->vty, (uint8_t *)tmp, cb);
+ buf += cb;
+ total_written += cb;
+ }
+ return total_written;
+ }
+#endif
+
Instead of adding #ifdefs in this file could these be implemented as some
functions exported by spapr_vof.c and called here without needing #ifdefs?
Maybe it could be part of VofMachineIfClass similar to setprop.
Regards,
BALATON Zoltan
for ( ; len > 0; len -= cb) {
cb = MIN(len, sizeof(tmp) - 1);
if (VOF_MEM_READ(buf, tmp, cb) != MEMTX_OK) {
@@ -594,6 +636,46 @@ static uint32_t vof_write(Vof *vof, uint32_t ihandle,
uint32_t buf,
return len;
}
+static uint32_t vof_read(Vof *vof, uint32_t ihandle, uint32_t buf,
+ uint32_t len)
+{
+ OfInstance *inst = (OfInstance *)
+ g_hash_table_lookup(vof->of_instances, GINT_TO_POINTER(ihandle));
+
+ if (!inst) {
+ trace_vof_error_read(ihandle);
+ return PROM_ERROR;
+ }
+
+#ifdef CONFIG_PSERIES
+ if (inst->vty) {
+ uint8_t tmp[VOF_VTY_BUF_SIZE];
+ unsigned cb = MIN(len, sizeof(tmp));
+ uint32_t bytes_read = vty_getchars(inst->vty, tmp, cb);
+ if (bytes_read > 0) {
+ if (VOF_MEM_WRITE(buf, tmp, bytes_read) != MEMTX_OK) {
+ trace_vof_error_read(ihandle);
+ return PROM_ERROR;
+ }
+ }
+ if (trace_event_get_state(TRACE_VOF_READ) &&
+ qemu_loglevel_mask(LOG_TRACE)) {
+ char trace_buf[VOF_VTY_BUF_SIZE + 1];
+ memcpy(trace_buf, tmp, bytes_read);
+ trace_buf[bytes_read] = '\0';
+ trace_vof_read(ihandle, bytes_read, trace_buf);
+ }
+ return bytes_read;
+ }
+#endif
+
+ /*
+ * For other devices, return 0 to indicate no data available.
+ * This allows GRUB to continue without blocking on input.
+ */
+ return 0;
+}
+
static void vof_claimed_dump(GArray *claimed)
{
int i;
@@ -906,6 +988,8 @@ static uint32_t vof_client_handle(MachineState *ms, void
*fdt, Vof *vof,
ret = vof_instance_to_path(fdt, vof, args[0], args[1], args[2]);
} else if (cmpserv("write", 3, 1)) {
ret = vof_write(vof, args[0], args[1], args[2]);
+ } else if (cmpserv("read", 3, 1)) {
+ ret = vof_read(vof, args[0], args[1], args[2]);
} else if (cmpserv("claim", 3, 1)) {
uint64_t ret64 = vof_claim(vof, args[0], args[1], args[2]);
diff --git a/include/hw/ppc/spapr_vio.h b/include/hw/ppc/spapr_vio.h
index 0ea0dbae8b..81e7c0b91b 100644
--- a/include/hw/ppc/spapr_vio.h
+++ b/include/hw/ppc/spapr_vio.h
@@ -136,6 +136,7 @@ static inline int spapr_vio_dma_set(SpaprVioDevice *dev,
uint64_t taddr,
int spapr_vio_send_crq(SpaprVioDevice *dev, uint8_t *crq);
SpaprVioDevice *vty_lookup(SpaprMachineState *spapr, target_ulong reg);
+int vty_getchars(SpaprVioDevice *sdev, uint8_t *buf, int max);
void vty_putchars(SpaprVioDevice *sdev, uint8_t *buf, int len);
void spapr_vty_create(SpaprVioBus *bus, Chardev *chardev);
void spapr_vlan_create(SpaprVioBus *bus, NICInfo *nd);
