[PATCH 1/8] tests/functional: Add remote interrupts test for PowerNV

[Aditya Gupta <adityag@linux.ibm.com>]

In the past there have been hard to recreate issues where XIVE changes
cause qemu crashes due to multi-socket interrupts such as in [1].

Add a functional test explicitly to test whether remote interrupts work.

The test can also work as additional boot test for multi-socket boot,
initrd boot test, as well as a check for e1000e to be working in powernv,
though that's not a target goal, and are additional benefits.

From docs/system/devices/net.rst:

  In order to check that the user mode network is working, you can ping
  the address 10.0.2.2 and verify that you got an address in the range
  10.0.2.x from the QEMU virtual DHCP server.

Hence use 10.0.2.2 with ping.

[1]: https://lore.kernel.org/qemu-devel/baf6c854-832b-4a2e-922f-d34e6dadf821@redhat.com/

Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
---
 tests/functional/ppc64/test_powernv.py | 86 ++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)

diff --git a/tests/functional/ppc64/test_powernv.py b/tests/functional/ppc64/test_powernv.py
index 0ea6c93e4287..17d2447815f9 100755
--- a/tests/functional/ppc64/test_powernv.py
+++ b/tests/functional/ppc64/test_powernv.py
@@ -9,6 +9,7 @@
 
 from qemu_test import LinuxKernelTest, Asset
 from qemu_test import wait_for_console_pattern
+from qemu_test import exec_command_and_wait_for_pattern
 
 class PowernvMachine(LinuxKernelTest):
 
@@ -27,6 +28,9 @@ class PowernvMachine(LinuxKernelTest):
          'buildroot/qemu_ppc64le_powernv8-2025.02/rootfs.ext2'),
         'aee2192b692077c4bde31cb56ce474424b358f17cec323d5c94af3970c9aada2')
 
+    def helper_exec_shell_command(self, command):
+        exec_command_and_wait_for_pattern(self, command, '#', self.panic_message)
+
     def do_test_linux_boot(self, command_line = KERNEL_COMMON_COMMAND_LINE):
         self.require_accelerator("tcg")
         kernel_path = self.ASSET_KERNEL.fetch()
@@ -71,6 +75,88 @@ def test_linux_smt_boot(self):
         wait_for_console_pattern(self, console_pattern, self.panic_message)
         wait_for_console_pattern(self, self.good_message, self.panic_message)
 
+    def test_linux_remote_interrupts(self):
+        self.require_accelerator("tcg")
+        self.set_machine('powernv')
+
+        # have more sockets with as few CPUs as possible, increasing the
+        # probability to have remote interrupts from one chip to another
+        # also have e1000e network device to generate interrupts
+        self.vm.add_args('-smp', '4,sockets=4,threads=1')
+        self.vm.add_args('-device', 'e1000e,netdev=net0')
+        self.vm.add_args('-netdev', 'user,id=net0')
+
+        kernel_path = self.ASSET_KERNEL.fetch()
+        rootfs_path = self.ASSET_INITRD.fetch()
+        self.vm.set_console()
+        self.vm.add_args('-kernel', kernel_path,
+            '-drive',
+            f'file={rootfs_path},format=raw,if=none,id=drive0,readonly=on',
+            '-append', 'root=/dev/nvme0n1 console=hvc0',
+            '-device', 'nvme,drive=drive0,bus=pcie.2,addr=0x0,serial=1234')
+        self.vm.launch()
+
+        # Wait for boot to complete
+        console_pattern = 'CPU maps initialized for 1 thread per core'
+        wait_for_console_pattern(self, console_pattern, self.panic_message)
+        console_pattern = 'smp: Brought up 4 nodes, 4 CPUs'
+        wait_for_console_pattern(self, console_pattern, self.panic_message)
+        wait_for_console_pattern(self, 'Run /sbin/init as init process',
+                                 self.panic_message)
+
+        # Wait for login prompt and login as root (no password in buildroot)
+        wait_for_console_pattern(self, 'login:', self.panic_message)
+        exec_command_and_wait_for_pattern(self, 'root', '#', self.panic_message)
+
+        # RX, TX interrupts to chip/cpu 1 & 2 respectively
+        self.helper_exec_shell_command(
+            "export RX_IRQ=$(awk '/eth0-rx/ {print $1}' /proc/interrupts | tr -d ':')")
+        self.helper_exec_shell_command(
+            "export TX_IRQ=$(awk '/eth0-tx/ {print $1}' /proc/interrupts | tr -d ':')")
+        self.helper_exec_shell_command("echo 1 > /proc/irq/$RX_IRQ/smp_affinity_list")
+        self.helper_exec_shell_command("echo 2 > /proc/irq/$TX_IRQ/smp_affinity_list")
+
+        # Capture interrupt counts before generating traffic
+        self.helper_exec_shell_command(
+            "export RX_BEFORE=$(awk '/eth0-rx/ {print $3}' /proc/interrupts)")
+        self.helper_exec_shell_command(
+            "export TX_BEFORE=$(awk '/eth0-tx/ {print $4}' /proc/interrupts)")
+
+        # Wait up to 15 seconds for eth0 link to come up
+        self.helper_exec_shell_command(
+            "c=0; while ! ip addr show eth0 | grep 'inet 10.0.2'; do "
+            "sleep 1; c=$((c+1)); [ $c -gt 15 ] && break; done")
+
+        fail_msg="Fail"
+        self.helper_exec_shell_command(f"export FAIL={fail_msg}")
+        exec_command_and_wait_for_pattern(self,
+            "ip addr show eth0 | grep 'inet 10.0.2' || echo $FAIL",
+            '#', fail_msg)
+
+        # Generate network traffic to trigger remote interrupts
+        # Ping QEMU's user-mode network gateway (10.0.2.2)
+        self.helper_exec_shell_command("ping -W2 -c5 10.0.2.2")
+
+        # Show final interrupt counts to verify remote interrupts occurred
+        self.helper_exec_shell_command("cat /proc/interrupts | grep eth0")
+
+        # Verify interrupt counts increased (whether interrupts were delivered)
+        self.helper_exec_shell_command(
+            "export RX_AFTER=$(awk '/eth0-rx/ {print $3}' /proc/interrupts)")
+        self.helper_exec_shell_command(
+            "export TX_AFTER=$(awk '/eth0-tx/ {print $4}' /proc/interrupts)")
+
+        # Check that interrupt counts increased
+        success_msg = "Interrupts increased"
+        self.helper_exec_shell_command(f"export PASS='{success_msg}'")
+
+        exec_command_and_wait_for_pattern(self,
+            "[ $RX_AFTER -gt $RX_BEFORE ] && echo $PASS || echo $FAIL",
+            success_msg, fail_msg)
+        exec_command_and_wait_for_pattern(self,
+            "[ $TX_AFTER -gt $TX_BEFORE ] && echo $PASS || echo $FAIL",
+            success_msg, fail_msg)
+
     def test_linux_big_boot(self):
         self.set_machine('powernv')
         self.vm.add_args('-smp', '16,threads=4,cores=2,sockets=2')
-- 
2.54.0