Round 4, and it might even be almost time to drop the 'RFC'. The basic platform support is working here, soft reset (for kexec) is implemented. We have the start of grant tables, and timers are working both using the in-kernel support and the userspace version. Everything should be surviving migration.
Timers do need locking, if I can't work out how to ensure that the vCPU's timer actually fires on that vCPU's own thread. In an uncommitted emacs buffer I have the start of a XenStore ring implementation; I'm hoping to make that just pass through to the real xenstored over its UNIX socket interface. I actually quite like the idea of having a "virtual XenStore" purely within qemu, but it's a bunch of code, and the one I have here to crib from is all in C++ so not very straightforward to port. So using the external xenstored is probably the right approach for now. Once that's done, I can make the driver backends cope with true Xen vs. emulated-Xen with ops tables for the evtchn/gnttab/etc (some of which is in Joao's original patch set waiting for me to get to that point). v4: • Add soft reset support near the beginning and thread it through the rest of the feature enablement. • Add PV timer support and advertise XENFEAT_safe_hvm_pvclock. • Add basic grant table mapping and [gs]et_version / query_size support. • Make xen_platform device build (and work) without CONFIG_XEN. • Fix Xen HVM mode not to require --xen-attach. v3: https://lore.kernel.org/qemu-devel/20221216004117.862106-1-dw...@infradead.org/ • Switch back to xen-version as KVM accelerator property, other review feedback and bug fixes. • Fix Hyper-V coexistence (ick, calling kvm_xen_init() again because hyperv_enabled() doesn't return the right answer the first time). • Implement event channel support, including GSI/PCI_INTX callback. • Implement 32-bit guest support. v2: https://lore.kernel.org/qemu-devel/20221209095612.689243-1-dw...@infradead.org/ • Attempt to implement migration support; every Xen enlightenment is now recorded either from vmstate_x86_cpu or from a new sysdev device created for that purpose. And — I believe — correctly restored, in the right order, on vmload. • The shared_info page is created as a proper overlay instead of abusing the underlying guest page. This is important because Windows doesn't even select a GPA which had RAM behind it beforehand. This will be extended to handle the grant frames too, in the fullness of time. • Set vCPU attributes from the correct vCPU thread to avoid deadlocks. • Carefully copy the entire hypercall argument structure from userspace instead of assuming that it's contiguous in HVA space. • Distinguish between "handled but intentionally returns -ENOSYS" and "no idea what that was" in hypercalls, allowing us to emit a GUEST_ERROR (actually, shouldn't that change to UNIMP?) on the latter. Experience shows that to we'll end up having to intentionally return -ENOSYS to a bunch of weird crap that ancient guests still attempt to use, including XenServer local hacks that nobody even remembers what they were (hvmop 0x101, anyone? Some old Windows PV driver appears to be trying to use it...). * Drop the '+xen' CPU property and present Xen CPUID instead of KVM unconditionally when running in Xen mode. Make the Xen CPUID coexist with Hyper-V CPUID as it should, though. • Add XEN_EMU and XENFV_MACHINE (the latter to be XEN_EMU||XEN) config options. Some more work on this, and the incestuous relationships between the KVM target code and the 'platform' code, is going to be required but it's probably better to get on with implementing the real code so we can see those interactions in all their glory, before losing too much sleep over the details here. • Drop the GSI-2 hack, and also the patch which made the PCI platform device have real RAM (which isn't needed now we have overlays, qv). • Drop the XenState and XenVcpuState from KVMState and CPUArchState respectively. The Xen-specific fields are natively included in CPUArchState now though, for migration purposes. And we don't keep a host pointer to the shared_info or vcpu_info at all any more. With the kernel doing everything for us, we don't actually need them. v1: https://lore.kernel.org/qemu-devel/20221205173137.607044-1-dw...@infradead.org/ v0: https://github.com/jpemartins/qemu/commits/xen-shim-rfc (Joao et al.) Ankur Arora (2): i386/xen: implement HVMOP_set_evtchn_upcall_vector i386/xen: implement HVMOP_set_param David Woodhouse (28): xen: add CONFIG_XENFV_MACHINE and CONFIG_XEN_EMU options for Xen emulation xen: Add XEN_DISABLED mode and make it default i386/kvm: Add xen-version KVM accelerator property and init KVM Xen support i386/hvm: Set Xen vCPU ID in KVM i386/xen: Implement SCHEDOP_poll and SCHEDOP_yield hw/xen: Add xen_overlay device for emulating shared xenheap pages i386/xen: add pc_machine_kvm_type to initialize XEN_EMULATE mode i386/xen: manage and save/restore Xen guest long_mode setting i386/xen: implement XENMEM_add_to_physmap_batch hw/xen: Add xen_evtchn device for event channel emulation i386/xen: Add support for Xen event channel delivery to vCPU hw/xen: Implement EVTCHNOP_status hw/xen: Implement EVTCHNOP_close hw/xen: Implement EVTCHNOP_unmask hw/xen: Implement EVTCHNOP_bind_virq hw/xen: Implement EVTCHNOP_bind_ipi hw/xen: Implement EVTCHNOP_send hw/xen: Implement EVTCHNOP_alloc_unbound hw/xen: Implement EVTCHNOP_bind_interdomain hw/xen: Implement EVTCHNOP_bind_vcpu hw/xen: Implement EVTCHNOP_reset hw/xen: Support HVM_PARAM_CALLBACK_TYPE_GSI callback hw/xen: Support HVM_PARAM_CALLBACK_TYPE_PCI_INTX callback kvm/i386: Add xen-gnttab-max-frames property hw/xen: Add xen_gnttab device for grant table emulation hw/xen: Support mapping grant frames i386/xen: Implement HYPERVISOR_grant_table_op and GNTTABOP_[gs]et_verson hw/xen: Implement GNTTABOP_query_size Joao Martins (17): include: import Xen public headers to include/standard-headers/ i386/kvm: handle Xen HVM cpuid leaves xen-platform: exclude vfio-pci from the PCI platform unplug xen-platform: allow its creation with XEN_EMULATE mode hw/xen_backend: refactor xen_be_init() i386/xen: handle guest hypercalls i386/xen: implement HYPERVISOR_xen_version i386/xen: implement HYPERVISOR_sched_op, SCHEDOP_shutdown i386/xen: implement HYPERVISOR_memory_op i386/xen: implement HYPERVISOR_hvm_op i386/xen: implement HYPERVISOR_vcpu_op i386/xen: handle VCPUOP_register_vcpu_info i386/xen: handle VCPUOP_register_vcpu_time_info i386/xen: handle VCPUOP_register_runstate_memory_area i386/xen: implement HYPERVISOR_event_channel_op i386/xen: add monitor commands to test event injection i386/xen: handle PV timer hypercalls accel/kvm/kvm-all.c | 2 + accel/xen/xen-all.c | 2 + hmp-commands.hx | 29 + hw/Kconfig | 1 + hw/i386/Kconfig | 5 + hw/i386/kvm/meson.build | 5 + hw/i386/kvm/xen_evtchn.c | 1254 ++++++++++++++++ hw/i386/kvm/xen_evtchn.h | 49 + hw/i386/kvm/xen_gnttab.c | 241 +++ hw/i386/kvm/xen_gnttab.h | 25 + hw/i386/kvm/xen_overlay.c | 265 ++++ hw/i386/kvm/xen_overlay.h | 26 + hw/i386/pc.c | 21 + hw/i386/xen/meson.build | 5 +- hw/i386/xen/xen_platform.c | 57 +- hw/xen/Kconfig | 3 + hw/xen/xen-legacy-backend.c | 40 +- include/hw/i386/pc.h | 3 + include/hw/xen/xen-legacy-backend.h | 3 + include/hw/xen/xen.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/io/console.h | 56 + include/standard-headers/xen/io/ring.h | 495 +++++++ include/standard-headers/xen/io/xs_wire.h | 153 ++ 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_int.h | 3 + include/sysemu/kvm_xen.h | 28 + meson.build | 1 + monitor/misc.c | 4 + softmmu/globals.c | 2 +- target/i386/cpu.c | 1 + target/i386/cpu.h | 16 + target/i386/kvm/kvm.c | 208 ++- target/i386/kvm/meson.build | 2 + target/i386/kvm/trace-events | 6 + target/i386/kvm/xen-compat.h | 51 + target/i386/kvm/xen-emu.c | 1566 ++++++++++++++++++++ target/i386/kvm/xen-emu.h | 33 + target/i386/machine.c | 25 + 54 files changed, 10676 insertions(+), 32 deletions(-)
