In 2019, Joao Martins posted a set of Linux KVM patches¹ which added support for hosting Xen HVM guests directly under KVM. Referenced from that post was a qemu git tree² which made use of it.
Now that the core of the kernel support has been merged upstream, I'm looking at updating the qemu support and potentially getting it merged too. This is the first attempt at the first round of that, adding the basics of KVM support with '-machine xenfv' and then just enough of the hypercall support to register the shared_info and vcpu_info areas before the guest kernel will panic when it can't use event channels for IPIs. Before I go much further, I think it needs all the runtime state (the shared info page address, etc.) to be correctly live migratable. Some pointers on how to do that would be welcomed. There's plenty more to heckle too... qemu-system-x86_64 -serial mon:stdio -machine xenfv,xen-version=0x4000a \ -cpu host,-kvm,+xen,+xen-vapic -display none \ -kernel /boot/vmlinuz-5.17.8-200.fc35.x86_64 \ -append "console=ttyS0,115200 earlyprintk=ttyS0,115200" \ --trace "kvm_xen*" ¹ https://lore.kernel.org/kvm/20190220201609.28290-1-joao.m.mart...@oracle.com/ ² https://github.com/jpemartins/qemu/commits/xen-shim-rfc Ankur Arora (2): kvm/ioapic: mark gsi-2 used in ioapic routing init i386/xen: handle event channel upcall related hypercalls David Woodhouse (1): i386/xen: Add xen-version machine property and init KVM Xen support Joao Martins (18): include: import xen public headers i386/kvm: handle Xen HVM cpuid leaves xen-platform-pci: allow its creation with XEN_EMULATE mode hw/xen_backend: refactor xen_be_init() pc_piix: handle XEN_EMULATE backend init xen-platform-pci: register xen-mmio as RAM for XEN_EMULATE xen_platform: exclude vfio-pci from the PCI platform unplug pc_piix: allow xenfv machine with XEN_EMULATE i386/xen: handle guest hypercalls i386/xen: implement HYPERCALL_xen_version i386/xen: set shared_info page i386/xen: implement HYPERVISOR_hvm_op i386/xen: implement HYPERVISOR_vcpu_op i386/xen: handle register_vcpu_info i386/xen: handle register_vcpu_time_memory_area i386/xen: handle register_runstate_memory_area i386/xen: implement HYPERVISOR_event_channel_op i386/xen: implement HYPERVISOR_sched_op accel/kvm/kvm-all.c | 11 + backends/cryptodev-vhost.c | 4 +- backends/vhost-user.c | 4 +- hw/block/vhost-user-blk.c | 45 +- hw/display/next-fb.c | 2 +- hw/i386/kvm/ioapic.c | 1 + hw/i386/pc.c | 32 + hw/i386/pc_piix.c | 19 +- hw/i386/xen/xen_platform.c | 37 +- hw/loongarch/Kconfig | 1 - hw/loongarch/acpi-build.c | 18 - hw/loongarch/virt.c | 62 -- hw/net/vhost_net.c | 8 +- hw/nvme/ctrl.c | 182 +++- hw/scsi/vhost-scsi-common.c | 4 +- hw/virtio/trace-events | 4 +- hw/virtio/vhost-user-fs.c | 4 +- hw/virtio/vhost-user-gpio.c | 26 +- hw/virtio/vhost-user-i2c.c | 4 +- hw/virtio/vhost-user-rng.c | 4 +- hw/virtio/vhost-user.c | 71 -- hw/virtio/vhost-vsock-common.c | 4 +- hw/virtio/vhost.c | 44 +- hw/xen/xen-legacy-backend.c | 62 +- include/hw/core/cpu.h | 2 + include/hw/i386/pc.h | 3 + include/hw/loongarch/virt.h | 5 - include/hw/virtio/vhost-user-gpio.h | 10 - include/hw/virtio/vhost-user.h | 18 - include/hw/virtio/vhost.h | 6 +- include/hw/virtio/virtio.h | 23 +- include/hw/xen/xen-legacy-backend.h | 5 + include/standard-headers/xen/arch-x86/cpuid.h | 118 +++ include/standard-headers/xen/arch-x86/xen-x86_32.h | 194 ++++ include/standard-headers/xen/arch-x86/xen-x86_64.h | 241 +++++ include/standard-headers/xen/arch-x86/xen.h | 398 ++++++++ include/standard-headers/xen/event_channel.h | 388 ++++++++ include/standard-headers/xen/features.h | 143 +++ include/standard-headers/xen/grant_table.h | 686 +++++++++++++ include/standard-headers/xen/hvm/hvm_op.h | 395 ++++++++ include/standard-headers/xen/hvm/params.h | 318 ++++++ include/standard-headers/xen/memory.h | 754 ++++++++++++++ include/standard-headers/xen/physdev.h | 383 +++++++ include/standard-headers/xen/sched.h | 202 ++++ include/standard-headers/xen/trace.h | 341 +++++++ include/standard-headers/xen/vcpu.h | 248 +++++ include/standard-headers/xen/version.h | 113 +++ include/standard-headers/xen/xen-compat.h | 46 + include/standard-headers/xen/xen.h | 1049 ++++++++++++++++++++ include/sysemu/kvm.h | 3 + include/sysemu/kvm_int.h | 3 + target/i386/cpu.c | 2 + target/i386/cpu.h | 12 + target/i386/kvm/kvm.c | 95 ++ target/i386/meson.build | 1 + target/i386/tcg/decode-new.c.inc | 3 +- target/i386/tcg/sysemu/excp_helper.c | 34 +- target/i386/trace-events | 6 + target/i386/xen-proto.h | 23 + target/i386/xen.c | 578 +++++++++++ target/i386/xen.h | 28 + target/s390x/tcg/cc_helper.c | 7 - target/s390x/tcg/insn-data.h.inc | 2 +- tests/qtest/libqos/virtio-gpio.c | 3 +- tests/qtest/migration-test.c | 20 +- 65 files changed, 7141 insertions(+), 421 deletions(-)