Make networking work in SO3 under QEMU virt

.gitignore

@@ -60,8 +60,10 @@ modules.order
 vmlinux.*dom*
 **/include/config/**
 
-# QEMU downloaded by build.sh script
-qemu
+# QEMU downloaded by build.sh script. Anchored: an unanchored "qemu" also
+# matches the DIRECTORIES of that name inside the layers (meta-qemu/
+# recipes-qemu/qemu/), which silently swallowed the recipe's patch files.
+/qemu
 
 # Backup files
 *~

build/meta-qemu/recipes-qemu/qemu/files/0001-qemu-8.2.2-r0-patches.inc

@@ -3,4 +3,5 @@
 SRC_URI += "\ 
     file://0001-virt.c.patch \ 
     file://0002-virt.h.patch \ 
+    file://0003-Kconfig.patch \ 
 "

build/meta-qemu/recipes-qemu/qemu/files/0001-qemu-8.2.2-r0/0001-virt.c.patch

@@ -1,6 +1,14 @@
 --- a/hw/arm/virt.c
 +++ b/hw/arm/virt.c
-@@ -82,6 +82,10 @@
+@@ -42,6 +42,7 @@
+ #include "hw/vfio/vfio-amd-xgbe.h"
+ #include "hw/display/ramfb.h"
+ #include "net/net.h"
++#include "hw/net/lan9118.h"
+ #include "sysemu/device_tree.h"
+ #include "sysemu/numa.h"
+ #include "sysemu/runstate.h"
+@@ -82,6 +83,10 @@
  #include "hw/char/pl011.h"
  #include "qemu/guest-random.h"
 
@@ -11,7 +19,7 @@
  #define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \
      static void virt_##major##_##minor##_class_init(ObjectClass *oc, \
                                                      void *data) \
-@@ -145,6 +149,12 @@
+@@ -145,6 +150,20 @@
      [VIRT_GIC_ITS] =            { 0x08080000, 0x00020000 },
      /* This redistributor space allows up to 2*64kB*123 CPUs */
      [VIRT_GIC_REDIST] =         { 0x080A0000, 0x00F60000 },
@@ -20,23 +28,45 @@
 +	[VIRT_KMI0] = 				{ 0x08801000, 0x00001000 },
 +	[VIRT_KMI1] = 				{ 0x08802000, 0x00001000 },
 +	[VIRT_ABSMOUSE] = 			{ 0x08803000, 0x00001000 },
++
++	/* SMSC LAN9118 Ethernet MAC. It sits with the other SO3-added devices
++	 * rather than at the 0x1a000000 the SO3 device trees inherited from
++	 * vexpress-a15: that address falls inside VIRT_PCIE_MMIO below, whose
++	 * gpex window covers the whole range and shadows anything mapped
++	 * underneath it (the guest then reads back nothing and the chip is
++	 * never detected). */
++	[VIRT_ETH] = 				{ 0x08804000, 0x00001000 },
 +
      [VIRT_UART] =               { 0x09000000, 0x00001000 },
      [VIRT_RTC] =                { 0x09010000, 0x00001000 },
      [VIRT_FW_CFG] =             { 0x09020000, 0x00000018 },
-@@ -199,6 +209,11 @@
+@@ -199,6 +218,12 @@
      [VIRT_SECURE_UART] = 8,
      [VIRT_ACPI_GED] = 9,
      [VIRT_MMIO] = 16, /* ...to 16 + NUM_VIRTIO_TRANSPORTS - 1 */
 +
 +	[VIRT_CLCD] = 10,
 +	[VIRT_KMI0] = 11,
 +	[VIRT_KMI1] = 12,
++	[VIRT_ETH] = 15,
 +
      [VIRT_GIC_V2M] = 48, /* ...to 48 + NUM_GICV2M_SPIS - 1 */
      [VIRT_SMMU] = 74,    /* ...to 74 + NUM_SMMU_IRQS - 1 */
      [VIRT_PLATFORM_BUS] = 112, /* ...to 112 + PLATFORM_BUS_NUM_IRQS -1 */
-@@ -2022,6 +2037,109 @@
+@@ -1487,6 +1512,12 @@
+     vms->bus = pci->bus;
+     if (vms->bus) {
+         for (i = 0; i < nb_nics; i++) {
++            /* Skip a slot an on-board NIC already took (the SO3 LAN9118
++             * created just before this call): the PCI code would reject its
++             * model with "Unsupported NIC model: lan9118". */
++            if (nd_table[i].instantiated) {
++                continue;
++            }
+             pci_nic_init_nofail(&nd_table[i], pci->bus, mc->default_nic, NULL);
+         }
+     }
+@@ -2022,6 +2053,109 @@
      }
  }
 
@@ -146,7 +176,33 @@
  static void machvirt_init(MachineState *machine)
  {
      VirtMachineState *vms = VIRT_MACHINE(machine);
-@@ -2326,6 +2444,51 @@
+@@ -2287,6 +2421,25 @@
+
+     create_rtc(vms);
+
++    /* SMSC LAN9118 Ethernet MAC — the NIC the SO3 smc911x driver
++     * (devices/net/smc911x_lwip.c, "smsc,smc911x") binds to, at the address
++     * and SPI the SO3 device trees declare. QEMU's own virt machine offers
++     * only virtio-net, which SO3 has no driver for.
++     *
++     * Taken from the legacy on-board NIC slot, so a run without -nic/-net
++     * leaves the machine exactly as it was and the guest simply finds no chip
++     * (smc911x_detect_chip() fails cleanly). scripts/st.sh passes
++     * "-nic user,model=lan9118".
++     *
++     * This has to happen BEFORE create_pcie(): that one hands every nd_table
++     * entry no on-board device has claimed to pci_nic_init_nofail(), which
++     * bails out with "Unsupported NIC model: lan9118".
++     */
++    if (nd_table[0].used) {
++        lan9118_init(&nd_table[0], vms->memmap[VIRT_ETH].base,
++                     qdev_get_gpio_in(vms->gic, vms->irqmap[VIRT_ETH]));
++    }
++
+     create_pcie(vms);
+
+     if (has_ged && aarch64 && firmware_loaded && virt_is_acpi_enabled(vms)) {
+@@ -2326,6 +2479,51 @@
                                 vms->fw_cfg, OBJECT(vms));
      }
 

build/meta-qemu/recipes-qemu/qemu/files/0001-qemu-8.2.2-r0/0002-virt.h.patch

@@ -1,6 +1,6 @@
 --- a/include/hw/arm/virt.h
 +++ b/include/hw/arm/virt.h
-@@ -58,6 +58,12 @@
+@@ -58,6 +58,13 @@
      VIRT_GIC_VCPU,
      VIRT_GIC_ITS,
      VIRT_GIC_REDIST,
@@ -9,6 +9,7 @@
 +	VIRT_KMI0,
 +	VIRT_KMI1,
 +	VIRT_ABSMOUSE,
++	VIRT_ETH,
 +
      VIRT_SMMU,
      VIRT_UART,

build/meta-qemu/recipes-qemu/qemu/files/0001-qemu-8.2.2-r0/0003-Kconfig.patch

@@ -0,0 +1,9 @@
+--- a/hw/arm/Kconfig
++++ b/hw/arm/Kconfig
+@@ -1,5 +1,6 @@
+ config ARM_VIRT
+     bool
++    select LAN9118 # SO3 Ethernet (smsc,smc911x)
+     imply PCI_DEVICES
+     imply TEST_DEVICES
+     imply VFIO_AMD_XGBE

doc/source/lwip.rst

@@ -23,18 +23,72 @@ chapter.
 
 .. note::
 
-   Networking is **opt-in**: it is enabled with ``CONFIG_NET`` and is *off* in
-   the default ``virt64_defconfig``. The smc911x MAC is present on boards such as
-   the ARM Versatile Express; QEMU's ``virt`` machine does not provide one, so a
-   different NIC driver is needed to exercise the stack there.
+   Networking is **opt-in**: ``CONFIG_NET`` plus ``CONFIG_SMC911X``. Both are on
+   in the four QEMU virt defconfigs (``virt32``/``virt64``, plain and ``_fb``),
+   and off everywhere else — rpi4 and verdin have no driver for their own MAC
+   yet.
+
+The NIC on QEMU virt
+====================
+
+QEMU's stock ``virt`` machine offers only virtio-net, which SO3 has no driver
+for. The so3 QEMU patch therefore adds an **SMSC LAN9118** to the machine model,
+next to the PL111/PL050 devices it already adds:
+
+- MMIO base ``0x08804000`` (``VIRT_ETH`` in the ``hw/arm/virt.c`` memmap,
+  ``ethernet@08804000`` in ``dts/virt{32,64}.dts``);
+- interrupt SPI 15 (``irqmap[VIRT_ETH]``, and ``interrupts = <0 15 4>`` in the
+  same DT nodes).
+
+Two details are worth knowing. The MAC is **not** at the ``0x1a000000`` the SO3
+device trees inherited from vexpress-a15: that address is inside the PCIe MMIO
+window, whose gpex alias covers the whole range and shadows anything mapped
+underneath, so the guest read back nothing and never detected the chip. And it
+is only instantiated when the command line fills the legacy on-board NIC slot
+(``-nic``/``-net``); without it the machine is exactly as it was and
+``smc911x_detect_chip()`` simply fails.
 
 Trying it out
 =============
 
-With ``CONFIG_NET`` enabled and a supported NIC, the ``ping`` application
-exercises the stack end to end. Under QEMU, ``st.sh`` attaches a **user-mode
-(slirp)** network device — QEMU itself plays DHCP, DNS and NAT, and forwards host
-port ``2222`` to the guest's port ``22`` — so nothing has to be set up on the host
-and no ``sudo`` is needed. The trade-off is that the guest is NAT'd and not
-reachable from the LAN. (``scripts/qemu-ifup.sh`` / ``qemu-ifdown.sh`` are
+``ping`` exercises the stack end to end::
+
+   / % ping -c 6 10.0.2.2
+   64 bytes from 10.0.2.2: icmp_seq=1 ttl=255 time=6.497070 ms
+   64 bytes from 10.0.2.2: icmp_seq=2 ttl=255 time=0.601074 ms
+   ...
+   6 packets transmitted, 6 received, 0.000000% packet loss
+
+``st.sh`` attaches two NICs on **user-mode (slirp)** networking — QEMU itself
+plays DHCP, DNS and NAT, so nothing has to be set up on the host and no ``sudo``
+is needed. The LAN9118 (``-nic user,model=lan9118``) is the one SO3 drives; the
+virtio-net device is there for the Linux agency of the AVZ boot chain, and
+carries the host port ``2222`` → guest port ``22`` forward. Each guest ignores
+the NIC it cannot drive. The trade-off of slirp is that the guest is NAT'd and
+not reachable from the LAN. (``scripts/qemu-ifup.sh`` / ``qemu-ifdown.sh`` are
 leftovers from the earlier ``tap``-and-bridge setup and are no longer used.)
+
+The interface comes up by DHCP during ``netif_add()``, so the address is
+announced on the console shortly after boot::
+
+   Network Interface Controller (NIC) found LAN9118
+   smc911x: detected LAN9118 controller
+   IP Network up and running with address 10.0.2.15
+
+Pinging past the slirp gateway (``10.0.2.2``) needs the **host** to let QEMU
+open ICMP sockets, otherwise slirp emulates the echo over UDP and relays back
+the port-unreachable it gets::
+
+   From 192.168.1.1 icmp_seq=1 Destination Port Unreachable
+
+The kernel decides that with ``net.ipv4.ping_group_range``, whose default on
+several distributions is the empty range ``1 0``. Widening it (``sysctl -w
+net.ipv4.ping_group_range="0 2147483647"``) lets slirp forward the echo for
+real. Nothing in SO3 is involved either way.
+
+.. note::
+
+   The **RX Status Level** the driver programs into ``FIFO_INT`` must be 0: the
+   controller raises the RSFL interrupt when the RX status FIFO holds *more*
+   entries than that level, so a level of 1 only interrupts once a second frame
+   has arrived, and every reception stays one frame behind.

scripts/st.sh

@@ -38,6 +38,10 @@ N_QEMU_INSTANCES=`ps -A | grep qemu-system | wc -l`
 launch_qemu() {
     QEMU_MAC_ADDR="$(printf 'DE:AD:BE:EF:%02X:%02X\n' $((N_QEMU_INSTANCES)) $((N_QEMU_INSTANCES)))"
 
+    # Second NIC (SO3's LAN9118, see ETH_OPT below) — must not collide with
+    # the virtio-net one above.
+    QEMU_ETH_MAC_ADDR="$(printf 'DE:AD:BE:EF:%02X:%02X\n' $((0x10 + N_QEMU_INSTANCES)) $((N_QEMU_INSTANCES)))"
+
     GDB_PORT=$((${GDB_PORT_BASE} + ${N_QEMU_INSTANCES}))
 
     echo -e "\033[01;36mMAC addr: " ${QEMU_MAC_ADDR} "\033[0;37m"
@@ -81,6 +85,24 @@ launch_qemu() {
         DISPLAY_OPT="-display none"
     fi
 
+    # Networking. Two NICs are attached, because the two kinds of guest this
+    # script boots need different ones:
+    #
+    #   * virtio-net for the Linux agency (AVZ boot chain) — it has no
+    #     smc911x node in its device tree, and hostfwd puts guest ssh on host
+    #     port 2222;
+    #   * an SMSC LAN9118 for SO3, whose only Ethernet driver is smc911x
+    #     (devices/net/smc911x_lwip.c). QEMU's stock 'virt' machine has no
+    #     such device; the so3 QEMU patch adds one at 0x08804000 / SPI 15 —
+    #     the address and IRQ the SO3 device trees declare — and creates it
+    #     only when the legacy on-board NIC slot is filled, which is what
+    #     -nic does here.
+    #
+    # Both sit on their own user-mode (slirp) stack: QEMU plays DHCP, DNS and
+    # NAT internally, so the guest gets 10.0.2.15 with no host setup and no
+    # sudo. Whichever guest is booted simply ignores the NIC it cannot drive.
+    ETH_OPT="-nic user,model=lan9118,mac=${QEMU_ETH_MAC_ADDR}"
+
     if [ "$IB_PLATFORM" == "virt64" ]; then
     QEMU_BIN="$IB_ROOT_DIR/qemu/build/qemu-system-aarch64"
     echo Starting on virt64
@@ -135,6 +157,7 @@ launch_qemu() {
 		${DISPLAY_OPT} \
 		-netdev user,id=n1,hostfwd=tcp::2222-:22 \
 		-device virtio-net-device,netdev=n1,mac=${QEMU_MAC_ADDR} \
+		${ETH_OPT} \
         	-gdb tcp::${GDB_PORT}
 	fi
 
@@ -158,6 +181,7 @@ launch_qemu() {
 		${DISPLAY_OPT} \
 		-netdev user,id=n1,hostfwd=tcp::2222-:22 \
 		-device virtio-net-device,netdev=n1,mac=${QEMU_MAC_ADDR} \
+		${ETH_OPT} \
         	-gdb tcp::${GDB_PORT}
 	fi
 

so3/so3/configs/virt32_defconfig

@@ -38,7 +38,7 @@ CONFIG_SCHED_FREQ_PREEMPTION=y
 CONFIG_UART=y
 CONFIG_IO_MAPPING_BASE=0xe0000000
 # CONFIG_I2C is not set
-# CONFIG_NET is not set
+CONFIG_NET=y
 # CONFIG_FB is not set
 # CONFIG_INPUT is not set
 # CONFIG_NS16550 is not set
@@ -52,6 +52,7 @@ CONFIG_GIC=y
 CONFIG_GIC_V2=y
 # CONFIG_PL050_KMI is not set
 # CONFIG_VIRT_INPUT is not set
+CONFIG_SMC911X=y
 
 #
 # SO3 Applications

so3/so3/configs/virt32_fb_defconfig

@@ -38,7 +38,7 @@ CONFIG_SCHED_FREQ_PREEMPTION=y
 CONFIG_UART=y
 CONFIG_IO_MAPPING_BASE=0xe0000000
 # CONFIG_I2C is not set
-# CONFIG_NET is not set
+CONFIG_NET=y
 CONFIG_FB=y
 CONFIG_INPUT=y
 # CONFIG_NS16550 is not set
@@ -55,6 +55,7 @@ CONFIG_PL111_CLCD=y
 # CONFIG_VIRTFB is not set
 CONFIG_PL050_KMI=y
 # CONFIG_VIRT_INPUT is not set
+CONFIG_SMC911X=y
 
 #
 # SO3 Applications

so3/so3/configs/virt64_defconfig

@@ -41,7 +41,7 @@ CONFIG_SCHED_FREQ_PREEMPTION=y
 CONFIG_UART=y
 CONFIG_IO_MAPPING_BASE=0xffff900000000000
 # CONFIG_I2C is not set
-# CONFIG_NET is not set
+CONFIG_NET=y
 # CONFIG_FB is not set
 # CONFIG_INPUT is not set
 # CONFIG_NS16550 is not set
@@ -55,6 +55,7 @@ CONFIG_GIC_V2=y
 # CONFIG_PL111_CLCD is not set
 # CONFIG_QEMU_RAMFB is not set
 # CONFIG_PL050_KMI is not set
+CONFIG_SMC911X=y
 
 #
 # SO3 Applications

so3/so3/configs/virt64_fb_defconfig

@@ -41,7 +41,7 @@ CONFIG_SCHED_FREQ_PREEMPTION=y
 CONFIG_UART=y
 CONFIG_IO_MAPPING_BASE=0xffff900000000000
 # CONFIG_I2C is not set
-# CONFIG_NET is not set
+CONFIG_NET=y
 CONFIG_FB=y
 CONFIG_INPUT=y
 # CONFIG_NS16550 is not set
@@ -57,6 +57,7 @@ CONFIG_PL111_CLCD=y
 # CONFIG_VIRTFB is not set
 CONFIG_PL050_KMI=y
 # CONFIG_VIRT_INPUT is not set
+CONFIG_SMC911X=y
 
 #
 # SO3 Applications

so3/so3/devices/net/Kconfig

@@ -1,7 +1,7 @@
 
 config SMC911X
 	bool "smc911x network interface"
-	depends on VIRT32
+	depends on VIRT32 || VIRT64
 	depends on NET