[PULL 14/23] pc-bios/s390-ccw: Add support for virtio-net-pci IPL

[Eric Farman <farman@linux.ibm.com>]

From: Zhuoying Cai <zycai@linux.ibm.com>

Enable network booting via virtio-net-pci by implementing PCI transport
support for virtio-net.

This patch also extends endianness handling for virtio PCI ring operations in
little-endian to ensure correct behavior on s390x.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
Reviewed-by: Jared Rossi <jrossi@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260924222949.147720-5-zycai@linux.ibm.com
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 pc-bios/s390-ccw/main.c       |  2 ++
 pc-bios/s390-ccw/netmain.c    |  8 ++++++-
 pc-bios/s390-ccw/virtio-net.c | 41 ++++++++++++++++++++++++++++-------
 pc-bios/s390-ccw/virtio-pci.c | 20 +++++++++++++++++
 4 files changed, 62 insertions(+), 9 deletions(-)

diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index d2a2ac3138..b06d67c563 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -342,7 +342,9 @@ static void ipl_pci_device(void)
         return;
     }
 
+    /* net, scsi, and block all intentionally use the same shared boot setup */
     switch (vdev->dev_type) {
+    case VIRTIO_ID_NET:
     case VIRTIO_ID_SCSI:
     case VIRTIO_ID_BLOCK:
         if (virtio_setup() == 0) {
diff --git a/pc-bios/s390-ccw/netmain.c b/pc-bios/s390-ccw/netmain.c
index bcb62bf6ca..dd02c5c71f 100644
--- a/pc-bios/s390-ccw/netmain.c
+++ b/pc-bios/s390-ccw/netmain.c
@@ -498,7 +498,13 @@ int netmain(void)
     sclp_setup();
     puts("Network boot starting...");
 
-    if (!virtio_ccw_net_setup()) {
+    /*
+     * CCW devices require subchannel enumeration here.
+     * PCI devices don't need specific net setup; the virtio-net-pci devices
+     * still follow the regular Virtio, PCI, and generic network setup.
+     */
+    if (virtio_get_device()->ipl_type == S390_IPL_TYPE_CCW &&
+        !virtio_ccw_net_setup()) {
         puts("No valid virtio ccw net device found.");
         return -1;
     }
diff --git a/pc-bios/s390-ccw/virtio-net.c b/pc-bios/s390-ccw/virtio-net.c
index 7bb3f8f551..632ce059d6 100644
--- a/pc-bios/s390-ccw/virtio-net.c
+++ b/pc-bios/s390-ccw/virtio-net.c
@@ -66,7 +66,22 @@ int virtio_net_init(void *mac_addr)
     rx_last_idx = 0;
 
     vdev->guest_features[0] = VIRTIO_NET_F_MAC_BIT;
-    virtio_ccw_setup(vdev);
+    switch (virtio_get_device()->ipl_type) {
+    case S390_IPL_TYPE_CCW:
+        if (virtio_ccw_setup(vdev)) {
+            puts("Setup failed for virtio-net-ccw");
+            return -1;
+        }
+        break;
+    case S390_IPL_TYPE_PCI:
+        if (virtio_pci_setup(vdev)) {
+            puts("Setup failed for virtio-net-pci");
+            return -1;
+        }
+        break;
+    default:
+        return -1;
+    }
 
     if (!(vdev->guest_features[0] & VIRTIO_NET_F_MAC_BIT)) {
         puts("virtio-net device does not support the MAC address feature");
@@ -118,22 +133,30 @@ int recv(int fd, void *buf, int maxlen, int flags)
     VRing *rxvq = &vdev->vrings[VQ_RX];
     int len, id;
     uint8_t *pkt;
+    uint16_t rx_used_idx, rx_avail_idx;
+    uint32_t rx_used_len, rx_used_id;
+    uint64_t rx_desc_addr;
 
-    if (rx_last_idx == rxvq->used->idx) {
+    rx_used_idx = virtio_tswap16(rxvq->used->idx);
+    if (rx_last_idx == rx_used_idx) {
         return 0;
     }
 
-    len = rxvq->used->ring[rx_last_idx % rxvq->num].len - virtio_net_hdr_size;
+    rx_used_len = virtio_tswap32(rxvq->used->ring[rx_last_idx % rxvq->num].len);
+    rx_used_id = virtio_tswap32(rxvq->used->ring[rx_last_idx % rxvq->num].id);
+
+    len = rx_used_len - virtio_net_hdr_size;
     if (len > maxlen) {
         puts("virtio-net: Receive buffer too small");
         len = maxlen;
     }
-    id = rxvq->used->ring[rx_last_idx % rxvq->num].id % rxvq->num;
-    pkt = (uint8_t *)(rxvq->desc[id].addr + virtio_net_hdr_size);
+    id = rx_used_id % rxvq->num;
+    rx_desc_addr = virtio_tswap64(rxvq->desc[id].addr);
+    pkt = (uint8_t *)(rx_desc_addr + virtio_net_hdr_size);
 
 #if DEBUG_VIRTIO_NET   /* Dump packet */
     int i;
-    printf("\nbuf %p: len=%i\n", (void *)rxvq->desc[id].addr, len);
+    printf("\nbuf %p: len=%i\n", (void *)rx_desc_addr, len);
     for (i = 0; i < 64; i++) {
         printf(" %02x", pkt[i]);
         if ((i % 16) == 15) {
@@ -147,8 +170,10 @@ int recv(int fd, void *buf, int maxlen, int flags)
     memcpy(buf, pkt, len);
 
     /* Mark buffer as available to the host again */
-    rxvq->avail->ring[rxvq->avail->idx % rxvq->num] = id;
-    rxvq->avail->idx = rxvq->avail->idx + 1;
+    rx_avail_idx = virtio_tswap16(rxvq->avail->idx);
+    rxvq->avail->ring[rx_avail_idx % rxvq->num] = virtio_tswap16(id);
+    rx_avail_idx++;
+    rxvq->avail->idx = virtio_tswap16(rx_avail_idx);
     vring_notify(rxvq);
 
     /* Move index to next entry */
diff --git a/pc-bios/s390-ccw/virtio-pci.c b/pc-bios/s390-ccw/virtio-pci.c
index 277c3ea68d..eb47e7c534 100644
--- a/pc-bios/s390-ccw/virtio-pci.c
+++ b/pc-bios/s390-ccw/virtio-pci.c
@@ -56,6 +56,10 @@ void virtio_pci_id2type(VDev *vdev, uint16_t device_id)
     case 0x1004:
         vdev->dev_type = VIRTIO_ID_SCSI;
         break;
+    case 0x1041:
+    case 0x1000:
+        vdev->dev_type = VIRTIO_ID_NET;
+        break;
     default:
         vdev->dev_type = 0;
     }
@@ -223,6 +227,17 @@ static int virtio_pci_get_scsi_config(void)
     return rc;
 }
 
+static int virtio_pci_get_net_config(void)
+{
+    VirtioNetConfig *cfg = &virtio_get_device()->config.net;
+
+    /*
+     * Byte-swapping is not needed as only the MAC address (byte array)
+     * is used here. Byte-swap if other fields are added.
+     */
+    return vpci_read_flex(d_cap.off, d_cap.bar, cfg, sizeof(VirtioNetConfig));
+}
+
 static int virtio_pci_negotiate(void)
 {
     int i, rc;
@@ -355,6 +370,7 @@ bool virtio_pci_is_supported(VDev *vdev)
         switch (vdev->dev_type) {
         case VIRTIO_ID_BLOCK:
         case VIRTIO_ID_SCSI:
+        case VIRTIO_ID_NET:
             return true;
         default:
             return false;
@@ -414,6 +430,10 @@ int virtio_pci_setup(VDev *vdev)
         vdev->cmd_vr_idx = 2;
         virtio_pci_get_scsi_config();
         break;
+    case VIRTIO_ID_NET:
+        vdev->nr_vqs = 2;
+        virtio_pci_get_net_config();
+        break;
     default:
         puts("Unsupported virtio device");
         return -ENODEV;
-- 
2.55.0