tests/avocado: Test Xen guest support under KVM

Exercise guests with a few different modes for interrupt delivery. In
particular we want to cover:

 • Xen event channel delivery via GSI to the I/O APIC
 • Xen event channel delivery via GSI to the i8259 PIC
 • MSIs routed to PIRQ event channels
 • GSIs routed to PIRQ event channels

As well as some variants of normal non-Xen stuff like MSI to vAPIC and
PCI INTx going to the I/O APIC and PIC, which ought to still work even
in Xen mode.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230403134920.2132362-12-alex.bennee@linaro.org>

tests/avocado/kvm_xen_guest.py

+# KVM Xen guest functional tests
+#
+# Copyright © 2021 Red Hat, Inc.
+# Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+#
+# Author:
+#  David Woodhouse <dwmw2@infradead.org>
+#  Alex Bennée <alex.bennee@linaro.org>
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import os
+
+from qemu.machine import machine
+
+from avocado_qemu import LinuxSSHMixIn
+from avocado_qemu import QemuSystemTest
+from avocado_qemu import wait_for_console_pattern
+
+class KVMXenGuest(QemuSystemTest, LinuxSSHMixIn):
+    """
+    :avocado: tags=arch:x86_64
+    :avocado: tags=machine:q35
+    :avocado: tags=accel:kvm
+    :avocado: tags=kvm_xen_guest
+    """
+
+    KERNEL_DEFAULT = 'printk.time=0 root=/dev/xvda console=ttyS0'
+
+    kernel_path = None
+    kernel_params = None
+
+    # Fetch assets from the kvm-xen-guest subdir of my shared test
+    # images directory on fileserver.linaro.org where you can find
+    # build instructions for how they where assembled.
+    def get_asset(self, name, sha1):
+        base_url = ('https://fileserver.linaro.org/s/'
+                    'kE4nCFLdQcoBF9t/download?'
+                    'path=%2Fkvm-xen-guest&files=' )
+        url = base_url + name
+        # use explicit name rather than failing to neatly parse the
+        # URL into a unique one
+        return self.fetch_asset(name=name, locations=(url), asset_hash=sha1)
+
+    def common_vm_setup(self):
+        # We also catch lack of KVM_XEN support if we fail to launch
+        self.require_accelerator("kvm")
+
+        self.vm.set_console()
+
+        self.vm.add_args("-accel", "kvm,xen-version=0x4000a,kernel-irqchip=split")
+        self.vm.add_args("-smp", "2")
+
+        self.kernel_path = self.get_asset("bzImage",
+                                          "367962983d0d32109998a70b45dcee4672d0b045")
+        self.rootfs = self.get_asset("rootfs.ext4",
+                                     "f1478401ea4b3fa2ea196396be44315bab2bb5e4")
+
+    def run_and_check(self):
+        self.vm.add_args('-kernel', self.kernel_path,
+                         '-append', self.kernel_params,
+                         '-drive',  f"file={self.rootfs},if=none,format=raw,id=drv0",
+                         '-device', 'xen-disk,drive=drv0,vdev=xvda',
+                         '-device', 'virtio-net-pci,netdev=unet',
+                         '-netdev', 'user,id=unet,hostfwd=:127.0.0.1:0-:22')
+
+        try:
+            self.vm.launch()
+        except machine.VMLaunchFailure as e:
+            if "Xen HVM guest support not present" in e.output:
+                self.cancel("KVM Xen support is not present "
+                            "(need v5.12+ kernel with CONFIG_KVM_XEN)")
+            elif "Property 'kvm-accel.xen-version' not found" in e.output:
+                self.cancel("QEMU not built with CONFIG_XEN_EMU support")
+            else:
+                raise e
+
+        self.log.info('VM launched, waiting for sshd')
+        console_pattern = 'Starting dropbear sshd: OK'
+        wait_for_console_pattern(self, console_pattern, 'Oops')
+        self.log.info('sshd ready')
+        self.ssh_connect('root', '', False)
+
+        self.ssh_command('cat /proc/cmdline')
+        self.ssh_command('dmesg | grep -e "Grant table initialized"')
+
+    def test_kvm_xen_guest(self):
+        """
+        :avocado: tags=kvm_xen_guest
+        """
+
+        self.common_vm_setup()
+
+        self.kernel_params = (self.KERNEL_DEFAULT +
+                              ' xen_emul_unplug=ide-disks')
+        self.run_and_check()
+        self.ssh_command('grep xen-pirq.*msi /proc/interrupts')
+
+    def test_kvm_xen_guest_nomsi(self):
+        """
+        :avocado: tags=kvm_xen_guest_nomsi
+        """
+
+        self.common_vm_setup()
+
+        self.kernel_params = (self.KERNEL_DEFAULT +
+                              ' xen_emul_unplug=ide-disks pci=nomsi')
+        self.run_and_check()
+        self.ssh_command('grep xen-pirq.* /proc/interrupts')
+
+    def test_kvm_xen_guest_noapic_nomsi(self):
+        """
+        :avocado: tags=kvm_xen_guest_noapic_nomsi
+        """
+
+        self.common_vm_setup()
+
+        self.kernel_params = (self.KERNEL_DEFAULT +
+                              ' xen_emul_unplug=ide-disks noapic pci=nomsi')
+        self.run_and_check()
+        self.ssh_command('grep xen-pirq /proc/interrupts')
+
+    def test_kvm_xen_guest_vapic(self):
+        """
+        :avocado: tags=kvm_xen_guest_vapic
+        """
+
+        self.common_vm_setup()
+        self.vm.add_args('-cpu', 'host,+xen-vapic')
+        self.kernel_params = (self.KERNEL_DEFAULT +
+                              ' xen_emul_unplug=ide-disks')
+        self.run_and_check()
+        self.ssh_command('grep xen-pirq /proc/interrupts')
+        self.ssh_command('grep PCI-MSI /proc/interrupts')
+
+    def test_kvm_xen_guest_novector(self):
+        """
+        :avocado: tags=kvm_xen_guest_novector
+        """
+
+        self.common_vm_setup()
+        self.kernel_params = (self.KERNEL_DEFAULT +
+                              ' xen_emul_unplug=ide-disks' +
+                              ' xen_no_vector_callback')
+        self.run_and_check()
+        self.ssh_command('grep xen-platform-pci /proc/interrupts')
+
+    def test_kvm_xen_guest_novector_nomsi(self):
+        """
+        :avocado: tags=kvm_xen_guest_novector_nomsi
+        """
+
+        self.common_vm_setup()
+
+        self.kernel_params = (self.KERNEL_DEFAULT +
+                              ' xen_emul_unplug=ide-disks pci=nomsi' +
+                              ' xen_no_vector_callback')
+        self.run_and_check()
+        self.ssh_command('grep xen-platform-pci /proc/interrupts')
+
+    def test_kvm_xen_guest_novector_noapic(self):
+        """
+        :avocado: tags=kvm_xen_guest_novector_noapic
+        """
+
+        self.common_vm_setup()
+        self.kernel_params = (self.KERNEL_DEFAULT +
+                              ' xen_emul_unplug=ide-disks' +
+                              ' xen_no_vector_callback noapic')
+        self.run_and_check()
+        self.ssh_command('grep xen-platform-pci /proc/interrupts')