[PULL 19/25] pc-bios/s390-ccw: Introduce virtio-pci functions

[Thomas Huth <thuth@redhat.com>]

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>
Acked-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Message-ID: <20260309003601.242634-12-jrossi@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 pc-bios/s390-ccw/virtio-pci.h |  80 ++++++++++++++++
 pc-bios/s390-ccw/virtio.h     |   3 +
 pc-bios/s390-ccw/virtio-pci.c | 167 ++++++++++++++++++++++++++++++++++
 pc-bios/s390-ccw/Makefile     |   2 +-
 4 files changed, 251 insertions(+), 1 deletion(-)
 create mode 100644 pc-bios/s390-ccw/virtio-pci.h
 create mode 100644 pc-bios/s390-ccw/virtio-pci.c

diff --git a/pc-bios/s390-ccw/virtio-pci.h b/pc-bios/s390-ccw/virtio-pci.h
new file mode 100644
index 00000000000..54c524f6986
--- /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 c3cb5a6ee3b..1ef64675f4a 100644
--- a/pc-bios/s390-ccw/virtio.h
+++ b/pc-bios/s390-ccw/virtio.h
@@ -18,6 +18,8 @@
 #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
 /* We've given up on this device. */
 #define VIRTIO_CONFIG_S_FAILED          0x80
 
@@ -255,6 +257,7 @@ 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];
 };
diff --git a/pc-bios/s390-ccw/virtio-pci.c b/pc-bios/s390-ccw/virtio-pci.c
new file mode 100644
index 00000000000..f6ce7ec7661
--- /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 0x1042:
+    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 = 0;
+
+    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/Makefile b/pc-bios/s390-ccw/Makefile
index a62fc9d7660..3e5dfb64d5d 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
 
-- 
2.53.0