VMX: use xAPIC mode on all processors

Results are undefined if xAPIC/x2APIC mode is not homogeneous on all processors.
So far things seemed to have mostly worked, but if you end up calling xapic_icr_write
from an x2APIC-mode processor the write is eaten and the IPI is not delivered.

Reported-by: Cathy Avery <cavery@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 18 insertions, 1 deletions

diff --git a/lib/x86/smp.c b/lib/x86/smp.c
index 7b1e0e1..2ac0ef7 100644
--- a/lib/x86/smp.c
+++ b/lib/x86/smp.c
@@ -130,3 +130,19 @@ void smp_init(void)
 
     atomic_inc(&active_cpus);
 }
+
+static void do_reset_apic(void *data)
+{
+    reset_apic();
+}
+
+void smp_reset_apic(void)
+{
+    int i;
+
+    reset_apic();
+    for (i = 1; i < cpu_count(); ++i)
+        on_cpu(i, do_reset_apic, 0);
+
+    atomic_inc(&active_cpus);
+}
diff --git a/lib/x86/smp.h b/lib/x86/smp.h
index 1453bb5..09dfa86 100644
--- a/lib/x86/smp.h
+++ b/lib/x86/smp.h
@@ -10,5 +10,6 @@ int cpus_active(void);
 void on_cpu(int cpu, void (*function)(void *data), void *data);
 void on_cpu_async(int cpu, void (*function)(void *data), void *data);
 void on_cpus(void (*function)(void *data), void *data);
+void smp_reset_apic(void);
 
 #endif
diff --git a/x86/vmx.c b/x86/vmx.c
index cbe6876..3f496ae 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -2081,7 +2081,7 @@ int main(int argc, const char *argv[])
 	hypercall_field = 0;
 
 	/* We want xAPIC mode to test MMIO passthrough from L1 (us) to L2.  */
-	reset_apic();
+	smp_reset_apic();
 
 	argv++;
 	argc--;