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, 72 insertions, 0 deletions

diff --git a/cpus-common.c b/cpus-common.c
index 39f355d..b0047e4 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -23,6 +23,7 @@
 #include "hw/core/cpu.h"
 #include "sysemu/cpus.h"
 #include "qemu/lockable.h"
+#include "trace/trace-root.h"
 
 static QemuMutex qemu_cpu_list_lock;
 static QemuCond exclusive_cond;
@@ -368,3 +369,74 @@ void process_queued_cpu_work(CPUState *cpu)
     qemu_mutex_unlock(&cpu->work_mutex);
     qemu_cond_broadcast(&qemu_work_cond);
 }
+
+/* Add a breakpoint.  */
+int cpu_breakpoint_insert(CPUState *cpu, vaddr pc, int flags,
+                          CPUBreakpoint **breakpoint)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+    CPUBreakpoint *bp;
+
+    if (cc->gdb_adjust_breakpoint) {
+        pc = cc->gdb_adjust_breakpoint(cpu, pc);
+    }
+
+    bp = g_malloc(sizeof(*bp));
+
+    bp->pc = pc;
+    bp->flags = flags;
+
+    /* keep all GDB-injected breakpoints in front */
+    if (flags & BP_GDB) {
+        QTAILQ_INSERT_HEAD(&cpu->breakpoints, bp, entry);
+    } else {
+        QTAILQ_INSERT_TAIL(&cpu->breakpoints, bp, entry);
+    }
+
+    if (breakpoint) {
+        *breakpoint = bp;
+    }
+
+    trace_breakpoint_insert(cpu->cpu_index, pc, flags);
+    return 0;
+}
+
+/* Remove a specific breakpoint.  */
+int cpu_breakpoint_remove(CPUState *cpu, vaddr pc, int flags)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+    CPUBreakpoint *bp;
+
+    if (cc->gdb_adjust_breakpoint) {
+        pc = cc->gdb_adjust_breakpoint(cpu, pc);
+    }
+
+    QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) {
+        if (bp->pc == pc && bp->flags == flags) {
+            cpu_breakpoint_remove_by_ref(cpu, bp);
+            return 0;
+        }
+    }
+    return -ENOENT;
+}
+
+/* Remove a specific breakpoint by reference.  */
+void cpu_breakpoint_remove_by_ref(CPUState *cpu, CPUBreakpoint *bp)
+{
+    QTAILQ_REMOVE(&cpu->breakpoints, bp, entry);
+
+    trace_breakpoint_remove(cpu->cpu_index, bp->pc, bp->flags);
+    g_free(bp);
+}
+
+/* Remove all matching breakpoints. */
+void cpu_breakpoint_remove_all(CPUState *cpu, int mask)
+{
+    CPUBreakpoint *bp, *next;
+
+    QTAILQ_FOREACH_SAFE(bp, &cpu->breakpoints, entry, next) {
+        if (bp->flags & mask) {
+            cpu_breakpoint_remove_by_ref(cpu, bp);
+        }
+    }
+}