Merge branch 'xenfv-kvm-15' of git://git.infradead.org/users/dwmw2/qemu into HEAD

This adds support for emulating Xen under Linux/KVM, based on kernel
patches which have been present since Linux v5.12. As with the kernel
support, it's derived from work started by João Martins of Oracle in
2018.

This series just adds the basic platform support — CPUID, hypercalls,
event channels, a stub of XenStore.

A full single-tenant internal implementation of XenStore, and patches
to make QEMU's Xen PV drivers work with this Xen emulation, are waiting
in the wings to be submitted in a follow-on patch series.

As noted in the documentation, it's enabled by setting the xen-version
property on the KVM accelerator, e.g.:

 qemu-system-x86_64 -serial mon:stdio -M q35 -display none -m 1G -smp 2 \
    -accel kvm,xen-version=0x4000e,kernel-irqchip=split \
    -kernel vmlinuz-6.0.7-301.fc37.x86_64 \
    -append "console=ttyS0 root=/dev/sda1" \
    -drive file=/var/lib/libvirt/images/fedora28.qcow2,if=none,id=disk \
    -device ahci,id=ahci -device ide-hd,drive=disk,bus=ahci.0

Even before this was merged, we've already been using it to find and fix
bugs in the Linux kernel Xen guest support:

https://lore.kernel.org/all/4bffa69a949bfdc92c4a18e5a1c3cbb3b94a0d32.camel@infradead.org/
https://lore.kernel.org/all/871qnunycr.ffs@tglx/

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 9b26582655..f2a6ea6a68 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2361,13 +2361,13 @@ static int kvm_init(MachineState *ms)
     static const char upgrade_note[] =
         "Please upgrade to at least kernel 2.6.29 or recent kvm-kmod\n"
         "(see http://sourceforge.net/projects/kvm).\n";
-    struct {
+    const struct {
         const char *name;
         int num;
     } num_cpus[] = {
         { "SMP",          ms->smp.cpus },
         { "hotpluggable", ms->smp.max_cpus },
-        { NULL, }
+        { /* end of list */ }
     }, *nc = num_cpus;
     int soft_vcpus_limit, hard_vcpus_limit;
     KVMState *s;
@@ -3305,7 +3305,7 @@ bool kvm_supports_guest_debug(void)
     return kvm_has_guest_debug;
 }
 
-int kvm_insert_breakpoint(CPUState *cpu, int type, hwaddr addr, hwaddr len)
+int kvm_insert_breakpoint(CPUState *cpu, int type, vaddr addr, vaddr len)
 {
     struct kvm_sw_breakpoint *bp;
     int err;
@@ -3343,7 +3343,7 @@ int kvm_insert_breakpoint(CPUState *cpu, int type, hwaddr addr, hwaddr len)
     return 0;
 }
 
-int kvm_remove_breakpoint(CPUState *cpu, int type, hwaddr addr, hwaddr len)
+int kvm_remove_breakpoint(CPUState *cpu, int type, vaddr addr, vaddr len)
 {
     struct kvm_sw_breakpoint *bp;
     int err;
@@ -3703,6 +3703,9 @@ static void kvm_accel_instance_init(Object *obj)
     s->kvm_dirty_ring_size = 0;
     s->notify_vmexit = NOTIFY_VMEXIT_OPTION_RUN;
     s->notify_window = 0;
+    s->xen_version = 0;
+    s->xen_gnttab_max_frames = 64;
+    s->xen_evtchn_max_pirq = 256;
 }
 
 /**