qemu-kvm/kvm-pc-bios-s390-ccw-Fix-boot-problem-with-virtio-net-de.patch

From 548a415cff7d590d86033902fb29d5e15f57d17f Mon Sep 17 00:00:00 2001
From: Thomas Huth <thuth@redhat.com>
Date: Thu, 16 Jan 2025 12:58:25 +0100
Subject: [PATCH 4/6] pc-bios/s390-ccw: Fix boot problem with virtio-net
 devices
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RH-Author: Thomas Huth <thuth@redhat.com>
RH-MergeRequest: 331: Fix boot problems when falling back from network to another boot device on s390x [RHEL10]
RH-Jira: RHEL-72717
RH-Acked-by: Cédric Le Goater <clg@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Commit: [3/4] f7ef8c63507c7f1ee8d05083f9540bee1697071c (thuth/qemu-kvm-cs)

When we are trying to boot from virtio-net devices, the
s390-ccw bios currently leaves the virtio-net device enabled
after using it. That means that the receiving virt queues will
continue to happily write incoming network packets into memory.
This can corrupt data of the following boot process. For example,
if you set up a second guest on a virtual network and create a
lot of broadcast traffic there, e.g. with:

 ping -i 0.02 -s 1400  -b 192.168.1.255

and then you try to boot a guest with two boot devices, a network
device first (which should not be bootable) and e.g. a bootable SCSI
CD second, then this guest will fail to load the kernel from the CD
image:

 $ qemu-system-s390x -m 2G -nographic -device virtio-scsi-ccw \
    -netdev tap,id=net0 -device virtio-net-ccw,netdev=net0,bootindex=1 \
    -drive if=none,file=test.iso,format=raw,id=cd1 \
    -device scsi-cd,drive=cd1,bootindex=2
 LOADPARM=[        ]

 Network boot device detected
 Network boot starting...
   Using MAC address: 52:54:00:12:34:56
   Requesting information via DHCP: done
   Using IPv4 address: 192.168.1.76
   Using TFTP server: 192.168.1.1
 Trying pxelinux.cfg files...
   TFTP error: ICMP ERROR "port unreachable"
   Receiving data:  0 KBytes
 Repeating TFTP read request...
   TFTP error: ICMP ERROR "port unreachable"
 Failed to load OS from network.
 Failed to IPL from this network!
 LOADPARM=[        ]

 Using virtio-scsi.

 ! virtio-scsi:setup:inquiry: response VS RESP=ff !
 ERROR: No suitable device for IPL. Halting...

We really have to shut up the virtio-net devices after we're not
using it anymore. The easiest way to do this is to simply reset
the device, so let's do that now.

Reviewed-by: Jared Rossi <jrossi@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Tested-by: Jared Rossi <jrossi@linux.ibm.com>
Message-ID: <20250116115826.192047-3-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 68c95ed1db070f7545e487e742715f01a545aab0)
---
 pc-bios/s390-ccw/netmain.c    | 33 +++++++++++++++++++++++----------
 pc-bios/s390-ccw/virtio-net.c |  5 +++++
 pc-bios/s390-ccw/virtio.h     |  1 +
 3 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/pc-bios/s390-ccw/netmain.c b/pc-bios/s390-ccw/netmain.c
index e46e470db4..335ea9b63e 100644
--- a/pc-bios/s390-ccw/netmain.c
+++ b/pc-bios/s390-ccw/netmain.c
@@ -153,19 +153,10 @@ static int tftp_load(filename_ip_t *fnip, void *buffer, int len)
     return rc;
 }
 
-static int net_init(filename_ip_t *fn_ip)
+static int net_init_ip(filename_ip_t *fn_ip)
 {
     int rc;
 
-    memset(fn_ip, 0, sizeof(filename_ip_t));
-
-    rc = virtio_net_init(mac);
-    if (rc < 0) {
-        puts("Could not initialize network device");
-        return -101;
-    }
-    fn_ip->fd = rc;
-
     printf("  Using MAC address: %02x:%02x:%02x:%02x:%02x:%02x\n",
            mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
 
@@ -221,11 +212,33 @@ static int net_init(filename_ip_t *fn_ip)
     return rc;
 }
 
+static int net_init(filename_ip_t *fn_ip)
+{
+    int rc;
+
+    memset(fn_ip, 0, sizeof(filename_ip_t));
+
+    rc = virtio_net_init(mac);
+    if (rc < 0) {
+        puts("Could not initialize network device");
+        return -101;
+    }
+    fn_ip->fd = rc;
+
+    rc = net_init_ip(fn_ip);
+    if (rc < 0) {
+        virtio_net_deinit();
+    }
+
+    return rc;
+}
+
 static void net_release(filename_ip_t *fn_ip)
 {
     if (fn_ip->ip_version == 4) {
         dhcp_send_release(fn_ip->fd);
     }
+    virtio_net_deinit();
 }
 
 /**
diff --git a/pc-bios/s390-ccw/virtio-net.c b/pc-bios/s390-ccw/virtio-net.c
index 578c89d0c5..301445bf97 100644
--- a/pc-bios/s390-ccw/virtio-net.c
+++ b/pc-bios/s390-ccw/virtio-net.c
@@ -140,3 +140,8 @@ int recv(int fd, void *buf, int maxlen, int flags)
 
     return len;
 }
+
+void virtio_net_deinit(void)
+{
+    virtio_reset(virtio_get_device());
+}
diff --git a/pc-bios/s390-ccw/virtio.h b/pc-bios/s390-ccw/virtio.h
index f13fa6f5fe..5c5e808a50 100644
--- a/pc-bios/s390-ccw/virtio.h
+++ b/pc-bios/s390-ccw/virtio.h
@@ -278,5 +278,6 @@ int virtio_reset(VDev *vdev);
 int virtio_setup_ccw(VDev *vdev);
 
 int virtio_net_init(void *mac_addr);
+void virtio_net_deinit(void);
 
 #endif /* VIRTIO_H */
-- 
2.39.3