On Tue, 2026-01-27 at 11:15 -0500, [email protected] wrote:
> From: Jared Rossi <[email protected]>
>
> Define common functionality for interacting with virtio-pci devices.
>
> Signed-off-by: Jared Rossi <[email protected]>
> ---
> pc-bios/s390-ccw/Makefile | 2 +-
> pc-bios/s390-ccw/virtio-pci.c | 168 ++++++++++++++++++++++++++++++++++
> pc-bios/s390-ccw/virtio-pci.h | 86 +++++++++++++++++
> pc-bios/s390-ccw/virtio.h | 1 +
> 4 files changed, 256 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..70abac0256
> --- /dev/null
> +++ b/pc-bios/s390-ccw/virtio-pci.c
> @@ -0,0 +1,168 @@
> +/*
> + * Functionality for virtio-pci
> + *
> + * Copyright 2025 IBM Corp.
> + * Author(s): Jared Rossi <[email protected]>
> + *
> + * 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 0x1001:
> + vdev->dev_type = VIRTIO_ID_BLOCK;
> + break;
> + case 0x1000: /* Other valid but currently unsupported virtio device
> types */
> + case 0x1004:
> + default:
> + vdev->dev_type = 0;
> + }
> +}
> +
> +int virtio_pci_reset(VDev *vdev)
> +{
> + int rc;
> + uint8_t status = VPCI_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..96c17ac3c7
> --- /dev/null
> +++ b/pc-bios/s390-ccw/virtio-pci.h
> @@ -0,0 +1,86 @@
> +/*
> + * Definitions for virtio-pci
> + *
> + * Copyright 2025 IBM Corp.
> + * Author(s): Jared Rossi <[email protected]>
> + *
> + * 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 VPCI_S_RESET 0
> +#define VPCI_S_ACKNOWLEDGE 1
> +#define VPCI_S_DRIVER 2
> +#define VPCI_S_DRIVER_OK 4
> +#define VPCI_S_FEATURES_OK 8
How are these status values different from VIRTIO_CONFIG_S_* in
pc-bios/s390-ccw/virtio.h? Maybe
expand that list instead?
The rest of this seems fine to me, though I do need another coffee.
> +
> +#define VIRTIO_F_VERSION_1 (1 << (32 - 32)) /* 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 0fdee8468c..0c34d59be2 100644
> --- a/pc-bios/s390-ccw/virtio.h
> +++ b/pc-bios/s390-ccw/virtio.h
> @@ -255,6 +255,7 @@ 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];
> };
