From: Jared Rossi <jrossi@linux.ibm.com>
Define common functionality for interacting with virtio-pci devices.
Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
---
pc-bios/s390-ccw/Makefile | 2 +-
pc-bios/s390-ccw/virtio-pci.c | 167 ++++++++++++++++++++++++++++++++++
pc-bios/s390-ccw/virtio-pci.h | 80 ++++++++++++++++
pc-bios/s390-ccw/virtio.h | 5 +
4 files changed, 253 insertions(+), 1 deletion(-)
create mode 100644 pc-bios/s390-ccw/virtio-pci.c
create mode 100644 pc-bios/s390-ccw/virtio-pci.h
diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
index a62fc9d766..3e5dfb64d5 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/pc-bios/s390-ccw/Makefile
@@ -35,7 +35,7 @@ QEMU_DGFLAGS = -MMD -MP -MT $@ -MF $(@D)/$(*F).d
OBJECTS = start.o main.o bootmap.o jump2ipl.o sclp.o menu.o netmain.o \
virtio.o virtio-net.o virtio-scsi.o virtio-blkdev.o cio.o dasd-ipl.o \
- virtio-ccw.o clp.o pci.o
+ virtio-ccw.o clp.o pci.o virtio-pci.o
SLOF_DIR := $(SRC_PATH)/../../roms/SLOF
diff --git a/pc-bios/s390-ccw/virtio-pci.c b/pc-bios/s390-ccw/virtio-pci.c
new file mode 100644
index 0000000000..2cfb84bf66
--- /dev/null
+++ b/pc-bios/s390-ccw/virtio-pci.c
@@ -0,0 +1,167 @@
+/*
+ * Functionality for virtio-pci
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Jared Rossi <jrossi@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "clp.h"
+#include "pci.h"
+#include "helper.h"
+#include "virtio.h"
+#include "bswap.h"
+#include "virtio-pci.h"
+#include "s390-time.h"
+#include <stdio.h>
+
+/* Variable offsets used for reads/writes to modern memory regions */
+VirtioPciCap c_cap; /* Common capabilities */
+VirtioPciCap d_cap; /* Device capabilities */
+VirtioPciCap n_cap; /* Notify capabilities */
+uint32_t notify_mult;
+uint16_t q_notify_offset;
+
+static int virtio_pci_set_status(uint8_t status)
+{
+ int rc = vpci_write_byte(c_cap.off + VPCI_C_OFFSET_STATUS, c_cap.bar, status);
+ if (rc) {
+ puts("Failed to write virtio-pci status");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static int virtio_pci_get_status(uint8_t *status)
+{
+ int rc = vpci_read_byte(c_cap.off + VPCI_C_OFFSET_STATUS, c_cap.bar, status);
+ if (rc) {
+ puts("Failed to read virtio-pci status");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+/* virtio spec v1.3 section 4.1.2.1 */
+void virtio_pci_id2type(VDev *vdev, uint16_t device_id)
+{
+ switch (device_id) {
+ case 0x1402:
+ case 0x1001:
+ vdev->dev_type = VIRTIO_ID_BLOCK;
+ break;
+ default:
+ vdev->dev_type = 0;
+ }
+}
+
+int virtio_pci_reset(VDev *vdev)
+{
+ int rc;
+ uint8_t status = VIRTIO_CONFIG_S_RESET;
+
+ rc = virtio_pci_set_status(status);
+ rc |= virtio_pci_get_status(&status);
+
+ if (rc || status) {
+ puts("Failed to reset virtio-pci device");
+ return 1;
+ }
+
+ return 0;
+}
+
+long virtio_pci_notify(int vq_id)
+{
+ uint32_t offset = n_cap.off + notify_mult * q_notify_offset;
+ return vpci_bswap16_write(offset, n_cap.bar, (uint16_t) vq_id);
+}
+
+/*
+ * Wrappers to byte swap common data sizes then write
+ */
+int vpci_write_byte(uint64_t offset, uint8_t pcias, uint8_t data)
+{
+ return pci_write(virtio_get_device()->pci_fh, offset, pcias, (uint64_t) data, 1);
+}
+
+int vpci_bswap16_write(uint64_t offset, uint8_t pcias, uint16_t data)
+{
+ uint64_t le_data = bswap16(data);
+ return pci_write(virtio_get_device()->pci_fh, offset, pcias, le_data, 2);
+}
+
+int vpci_bswap32_write(uint64_t offset, uint8_t pcias, uint32_t data)
+{
+ uint64_t le_data = bswap32(data);
+ return pci_write(virtio_get_device()->pci_fh, offset, pcias, le_data, 4);
+}
+
+int vpci_bswap64_write(uint64_t offset, uint8_t pcias, uint64_t data)
+{
+ uint64_t le_data = bswap64(data);
+ return pci_write(virtio_get_device()->pci_fh, offset, pcias, le_data, 8);
+}
+
+/*
+ * Wrappers to read common data sizes then byte swap
+ */
+int vpci_read_byte(uint64_t offset, uint8_t pcias, uint8_t *buf)
+{
+ return pci_read(virtio_get_device()->pci_fh, offset, pcias, buf, 1);
+}
+
+int vpci_read_bswap16(uint64_t offset, uint8_t pcias, uint16_t *buf)
+{
+ int rc = pci_read(virtio_get_device()->pci_fh, offset, pcias, buf, 2);
+ *buf = bswap16(*buf);
+ return rc;
+}
+
+int vpci_read_bswap32(uint64_t offset, uint8_t pcias, uint32_t *buf)
+{
+ int rc = pci_read(virtio_get_device()->pci_fh, offset, pcias, buf, 4);
+ *buf = bswap32(*buf);
+ return rc;
+}
+
+int vpci_read_bswap64(uint64_t offset, uint8_t pcias, uint64_t *buf)
+{
+ int rc = pci_read(virtio_get_device()->pci_fh, offset, pcias, buf, 8);
+ *buf = bswap64(*buf);
+ return rc;
+}
+
+/*
+ * Read to an arbitrary length buffer without byte swapping
+ */
+int vpci_read_flex(uint64_t offset, uint8_t pcias, void *buf, int len)
+{
+ uint8_t readlen;
+ int rc;
+ int remaining = len;
+
+ /* Read bytes in powers of 2, up to a maximum of 8 bytes per read */
+ while (remaining) {
+ for (int i = 3; i >= 0; i--) {
+ readlen = 1 << i;
+ if (remaining >= readlen) {
+ break;
+ }
+ }
+
+ rc = pci_read(virtio_get_device()->pci_fh, offset, pcias, buf, readlen);
+ if (rc) {
+ return -1;
+ }
+
+ remaining -= readlen;
+ buf += readlen;
+ offset += readlen;
+ }
+
+ return 0;
+}
diff --git a/pc-bios/s390-ccw/virtio-pci.h b/pc-bios/s390-ccw/virtio-pci.h
new file mode 100644
index 0000000000..54c524f698
--- /dev/null
+++ b/pc-bios/s390-ccw/virtio-pci.h
@@ -0,0 +1,80 @@
+/*
+ * Definitions for virtio-pci
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Jared Rossi <jrossi@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef VIRTIO_PCI_H
+#define VIRTIO_PCI_H
+
+/* Common configuration */
+#define VPCI_CAP_COMMON_CFG 1
+/* Notifications */
+#define VPCI_CAP_NOTIFY_CFG 2
+/* ISR access */
+#define VPCI_CAP_ISR_CFG 3
+/* Device specific configuration */
+#define VPCI_CAP_DEVICE_CFG 4
+/* PCI configuration access */
+#define VPCI_CAP_PCI_CFG 5
+/* Additional shared memory capability */
+#define VPCI_CAP_SHARED_MEMORY_CFG 8
+/* PCI vendor data configuration */
+#define VPCI_CAP_VENDOR_CFG 9
+
+/* Offsets within capability header */
+#define VPCI_CAP_VNDR 0
+#define VPCI_CAP_NEXT 1
+#define VPCI_CAP_LEN 2
+#define VPCI_CAP_CFG_TYPE 3
+#define VPCI_CAP_BAR 4
+#define VPCI_CAP_OFFSET 8
+#define VPCI_CAP_LENGTH 12
+
+#define VPCI_N_CAP_MULT 16 /* Notify multiplier, VPCI_CAP_NOTIFY_CFG only */
+
+/* Common Area Offsets for virtio-pci queue */
+#define VPCI_C_OFFSET_DFSELECT 0
+#define VPCI_C_OFFSET_DF 4
+#define VPCI_C_OFFSET_GFSELECT 8
+#define VPCI_C_OFFSET_GF 12
+#define VPCI_C_COMMON_NUMQ 18
+#define VPCI_C_OFFSET_STATUS 20
+#define VPCI_C_OFFSET_Q_SELECT 22
+#define VPCI_C_OFFSET_Q_SIZE 24
+#define VPCI_C_OFFSET_Q_ENABLE 28
+#define VPCI_C_OFFSET_Q_NOFF 30
+#define VPCI_C_OFFSET_Q_DESCLO 32
+#define VPCI_C_OFFSET_Q_DESCHI 36
+#define VPCI_C_OFFSET_Q_AVAILLO 40
+#define VPCI_C_OFFSET_Q_AVAILHI 44
+#define VPCI_C_OFFSET_Q_USEDLO 48
+#define VPCI_C_OFFSET_Q_USEDHI 52
+
+#define VIRTIO_F_VERSION_1 1 /* Feature bit 32 */
+
+struct VirtioPciCap {
+ uint8_t bar; /* Which PCIAS it's in */
+ uint32_t off; /* Offset within bar */
+};
+typedef struct VirtioPciCap VirtioPciCap;
+
+void virtio_pci_id2type(VDev *vdev, uint16_t device_id);
+int virtio_pci_reset(VDev *vdev);
+long virtio_pci_notify(int vq_id);
+
+int vpci_read_flex(uint64_t offset, uint8_t pcias, void *buf, int len);
+int vpci_read_bswap64(uint64_t offset, uint8_t pcias, uint64_t *buf);
+int vpci_read_bswap32(uint64_t offset, uint8_t pcias, uint32_t *buf);
+int vpci_read_bswap16(uint64_t offset, uint8_t pcias, uint16_t *buf);
+int vpci_read_byte(uint64_t offset, uint8_t pcias, uint8_t *buf);
+
+int vpci_bswap64_write(uint64_t offset, uint8_t pcias, uint64_t data);
+int vpci_bswap32_write(uint64_t offset, uint8_t pcias, uint32_t data);
+int vpci_bswap16_write(uint64_t offset, uint8_t pcias, uint16_t data);
+int vpci_write_byte(uint64_t offset, uint8_t pcias, uint8_t data);
+
+#endif
diff --git a/pc-bios/s390-ccw/virtio.h b/pc-bios/s390-ccw/virtio.h
index c3cb5a6ee3..0e7dbdb64c 100644
--- a/pc-bios/s390-ccw/virtio.h
+++ b/pc-bios/s390-ccw/virtio.h
@@ -18,6 +18,10 @@
#define VIRTIO_CONFIG_S_DRIVER 2
/* Driver has used its parts of the config, and is happy */
#define VIRTIO_CONFIG_S_DRIVER_OK 4
+/* Feature negotiation complete */
+#define VIRTIO_CONFIG_S_FEATURES_OK 8
+/* Clear status byte */
+#define VIRTIO_CONFIG_S_RESET 0x00
/* We've given up on this device. */
#define VIRTIO_CONFIG_S_FAILED 0x80
@@ -255,6 +259,7 @@ struct VDev {
uint8_t scsi_dev_heads;
bool scsi_device_selected;
ScsiDevice selected_scsi_device;
+ uint32_t pci_fh;
uint32_t max_transfer;
uint32_t guest_features[2];
};
--
2.52.0On Tue, 2026-03-03 at 21:59 -0500, jrossi@linux.ibm.com wrote:
> From: Jared Rossi <jrossi@linux.ibm.com>
>
> Define common functionality for interacting with virtio-pci devices.
>
> Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
> ---
> pc-bios/s390-ccw/Makefile | 2 +-
> pc-bios/s390-ccw/virtio-pci.c | 167 ++++++++++++++++++++++++++++++++++
> pc-bios/s390-ccw/virtio-pci.h | 80 ++++++++++++++++
> pc-bios/s390-ccw/virtio.h | 5 +
> 4 files changed, 253 insertions(+), 1 deletion(-)
> create mode 100644 pc-bios/s390-ccw/virtio-pci.c
> create mode 100644 pc-bios/s390-ccw/virtio-pci.h
>
...snip...
(Only comment I had in here was the s/0x1402/0x1042/ that Thomas pointed out.)
> diff --git a/pc-bios/s390-ccw/virtio-pci.h b/pc-bios/s390-ccw/virtio-pci.h
> new file mode 100644
> index 0000000000..54c524f698
> --- /dev/null
> +++ b/pc-bios/s390-ccw/virtio-pci.h
> @@ -0,0 +1,80 @@
> +/*
> + * Definitions for virtio-pci
> + *
> + * Copyright 2025 IBM Corp.
> + * Author(s): Jared Rossi <jrossi@linux.ibm.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#ifndef VIRTIO_PCI_H
> +#define VIRTIO_PCI_H
> +
> +/* Common configuration */
> +#define VPCI_CAP_COMMON_CFG 1
> +/* Notifications */
> +#define VPCI_CAP_NOTIFY_CFG 2
> +/* ISR access */
> +#define VPCI_CAP_ISR_CFG 3
> +/* Device specific configuration */
> +#define VPCI_CAP_DEVICE_CFG 4
> +/* PCI configuration access */
> +#define VPCI_CAP_PCI_CFG 5
> +/* Additional shared memory capability */
> +#define VPCI_CAP_SHARED_MEMORY_CFG 8
> +/* PCI vendor data configuration */
> +#define VPCI_CAP_VENDOR_CFG 9
> +
> +/* Offsets within capability header */
> +#define VPCI_CAP_VNDR 0
> +#define VPCI_CAP_NEXT 1
> +#define VPCI_CAP_LEN 2
> +#define VPCI_CAP_CFG_TYPE 3
> +#define VPCI_CAP_BAR 4
> +#define VPCI_CAP_OFFSET 8
> +#define VPCI_CAP_LENGTH 12
> +
> +#define VPCI_N_CAP_MULT 16 /* Notify multiplier, VPCI_CAP_NOTIFY_CFG only */
> +
> +/* Common Area Offsets for virtio-pci queue */
> +#define VPCI_C_OFFSET_DFSELECT 0
> +#define VPCI_C_OFFSET_DF 4
> +#define VPCI_C_OFFSET_GFSELECT 8
> +#define VPCI_C_OFFSET_GF 12
> +#define VPCI_C_COMMON_NUMQ 18
> +#define VPCI_C_OFFSET_STATUS 20
> +#define VPCI_C_OFFSET_Q_SELECT 22
> +#define VPCI_C_OFFSET_Q_SIZE 24
> +#define VPCI_C_OFFSET_Q_ENABLE 28
> +#define VPCI_C_OFFSET_Q_NOFF 30
> +#define VPCI_C_OFFSET_Q_DESCLO 32
> +#define VPCI_C_OFFSET_Q_DESCHI 36
> +#define VPCI_C_OFFSET_Q_AVAILLO 40
> +#define VPCI_C_OFFSET_Q_AVAILHI 44
> +#define VPCI_C_OFFSET_Q_USEDLO 48
> +#define VPCI_C_OFFSET_Q_USEDHI 52
> +
> +#define VIRTIO_F_VERSION_1 1 /* Feature bit 32 */
> +
> +struct VirtioPciCap {
> + uint8_t bar; /* Which PCIAS it's in */
> + uint32_t off; /* Offset within bar */
> +};
> +typedef struct VirtioPciCap VirtioPciCap;
> +
> +void virtio_pci_id2type(VDev *vdev, uint16_t device_id);
> +int virtio_pci_reset(VDev *vdev);
> +long virtio_pci_notify(int vq_id);
> +
> +int vpci_read_flex(uint64_t offset, uint8_t pcias, void *buf, int len);
> +int vpci_read_bswap64(uint64_t offset, uint8_t pcias, uint64_t *buf);
> +int vpci_read_bswap32(uint64_t offset, uint8_t pcias, uint32_t *buf);
> +int vpci_read_bswap16(uint64_t offset, uint8_t pcias, uint16_t *buf);
> +int vpci_read_byte(uint64_t offset, uint8_t pcias, uint8_t *buf);
> +
> +int vpci_bswap64_write(uint64_t offset, uint8_t pcias, uint64_t data);
> +int vpci_bswap32_write(uint64_t offset, uint8_t pcias, uint32_t data);
> +int vpci_bswap16_write(uint64_t offset, uint8_t pcias, uint16_t data);
> +int vpci_write_byte(uint64_t offset, uint8_t pcias, uint8_t data);
I know it's pedantic, but since the reads are vpci_read_bXXXX while the writes are vcpi_bXXXX_write
(except the single byte case) could we make them consistent, please? (Soft preference for
vpci_read/write_bXXXX, but I don't much care.)
> +
> +#endif
> diff --git a/pc-bios/s390-ccw/virtio.h b/pc-bios/s390-ccw/virtio.h
> index c3cb5a6ee3..0e7dbdb64c 100644
> --- a/pc-bios/s390-ccw/virtio.h
> +++ b/pc-bios/s390-ccw/virtio.h
> @@ -18,6 +18,10 @@
> #define VIRTIO_CONFIG_S_DRIVER 2
> /* Driver has used its parts of the config, and is happy */
> #define VIRTIO_CONFIG_S_DRIVER_OK 4
> +/* Feature negotiation complete */
> +#define VIRTIO_CONFIG_S_FEATURES_OK 8
> +/* Clear status byte */
> +#define VIRTIO_CONFIG_S_RESET 0x00
Heh, in v3 I wondered if you could add the new status bit(s) here. Buuuut... :)
Virtio section 2.1 defines "NEEDS_RESET" as 64 (0x40). Of course it says that the status field
starts as zero and is reinitialized to zero BY a reset, which is what you end up doing. Its
placement here between FEATURES_OK and FAILED with their spec-accurate definitions, but with a
different definition had me puzzled. Maybe move it to the top of this list, and rename it to
..._S_INIT or ..._S_ZERO or something? (Or don't define it and just set it to zero in the code.)
> /* We've given up on this device. */
> #define VIRTIO_CONFIG_S_FAILED 0x80
>
> @@ -255,6 +259,7 @@ struct VDev {
> uint8_t scsi_dev_heads;
> bool scsi_device_selected;
> ScsiDevice selected_scsi_device;
> + uint32_t pci_fh;
> uint32_t max_transfer;
> uint32_t guest_features[2];
> };
On 04/03/2026 03.59, jrossi@linux.ibm.com wrote:
> From: Jared Rossi <jrossi@linux.ibm.com>
>
> Define common functionality for interacting with virtio-pci devices.
>
> Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
> ---
...
> diff --git a/pc-bios/s390-ccw/virtio-pci.c b/pc-bios/s390-ccw/virtio-pci.c
> new file mode 100644
> index 0000000000..2cfb84bf66
> --- /dev/null
> +++ b/pc-bios/s390-ccw/virtio-pci.c
> @@ -0,0 +1,167 @@
> +/*
> + * Functionality for virtio-pci
> + *
> + * Copyright 2025 IBM Corp.
> + * Author(s): Jared Rossi <jrossi@linux.ibm.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "clp.h"
> +#include "pci.h"
> +#include "helper.h"
> +#include "virtio.h"
> +#include "bswap.h"
> +#include "virtio-pci.h"
> +#include "s390-time.h"
> +#include <stdio.h>
> +
> +/* Variable offsets used for reads/writes to modern memory regions */
> +VirtioPciCap c_cap; /* Common capabilities */
> +VirtioPciCap d_cap; /* Device capabilities */
> +VirtioPciCap n_cap; /* Notify capabilities */
> +uint32_t notify_mult;
> +uint16_t q_notify_offset;
> +
> +static int virtio_pci_set_status(uint8_t status)
> +{
> + int rc = vpci_write_byte(c_cap.off + VPCI_C_OFFSET_STATUS, c_cap.bar, status);
> + if (rc) {
> + puts("Failed to write virtio-pci status");
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +static int virtio_pci_get_status(uint8_t *status)
> +{
> + int rc = vpci_read_byte(c_cap.off + VPCI_C_OFFSET_STATUS, c_cap.bar, status);
> + if (rc) {
> + puts("Failed to read virtio-pci status");
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +/* virtio spec v1.3 section 4.1.2.1 */
> +void virtio_pci_id2type(VDev *vdev, uint16_t device_id)
> +{
> + switch (device_id) {
> + case 0x1402:
I think it's 0x1042, not 0x1402 ?
> + case 0x1001:
> + vdev->dev_type = VIRTIO_ID_BLOCK;
> + break;
> + default:
> + vdev->dev_type = 0;
> + }
> +}
Thomas
On 3/4/26 4:18 AM, Thomas Huth wrote:
> On 04/03/2026 03.59, jrossi@linux.ibm.com wrote:
>> From: Jared Rossi <jrossi@linux.ibm.com>
>>
>> Define common functionality for interacting with virtio-pci devices.
>>
>> Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
>> ---
> ...
>> diff --git a/pc-bios/s390-ccw/virtio-pci.c
>> b/pc-bios/s390-ccw/virtio-pci.c
>> new file mode 100644
>> index 0000000000..2cfb84bf66
>> --- /dev/null
>> +++ b/pc-bios/s390-ccw/virtio-pci.c
>> @@ -0,0 +1,167 @@
>> +/*
>> + * Functionality for virtio-pci
>> + *
>> + * Copyright 2025 IBM Corp.
>> + * Author(s): Jared Rossi <jrossi@linux.ibm.com>
>> + *
>> + * SPDX-License-Identifier: GPL-2.0-or-later
>> + */
>> +
>> +#include "clp.h"
>> +#include "pci.h"
>> +#include "helper.h"
>> +#include "virtio.h"
>> +#include "bswap.h"
>> +#include "virtio-pci.h"
>> +#include "s390-time.h"
>> +#include <stdio.h>
>> +
>> +/* Variable offsets used for reads/writes to modern memory regions */
>> +VirtioPciCap c_cap; /* Common capabilities */
>> +VirtioPciCap d_cap; /* Device capabilities */
>> +VirtioPciCap n_cap; /* Notify capabilities */
>> +uint32_t notify_mult;
>> +uint16_t q_notify_offset;
>> +
>> +static int virtio_pci_set_status(uint8_t status)
>> +{
>> + int rc = vpci_write_byte(c_cap.off + VPCI_C_OFFSET_STATUS,
>> c_cap.bar, status);
>> + if (rc) {
>> + puts("Failed to write virtio-pci status");
>> + return -EIO;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int virtio_pci_get_status(uint8_t *status)
>> +{
>> + int rc = vpci_read_byte(c_cap.off + VPCI_C_OFFSET_STATUS,
>> c_cap.bar, status);
>> + if (rc) {
>> + puts("Failed to read virtio-pci status");
>> + return -EIO;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/* virtio spec v1.3 section 4.1.2.1 */
>> +void virtio_pci_id2type(VDev *vdev, uint16_t device_id)
>> +{
>> + switch (device_id) {
>> + case 0x1402:
>
> I think it's 0x1042, not 0x1402 ?
Good catch. You are correct. I'll fix it.
Thanks again,
Jared Rossi
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