x86/HVM: meet xentrace's expectations on emulation event data

According to the logic in hvm_mmio_assist_process(), 64 bits of data are
expected with 64-bit addresses, and 32 bits of data with 32-bit ones. I
don't think this is very reasonable, but I'm also not going to touch the
consumer side, the more that it is anyway not very helpful for the code
here to only ever supply 32 bits of data (despite the field being 64
bits wide, and having been even in the 32-bit days of Xen).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index dbf8b81a3477aec616658bbad52256af0b3916d3..dec5951b997c5de46ce5f42e8f0202b92e3c6eb1 100644 (file)
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -30,7 +30,7 @@
 static void hvmtrace_io_assist(const ioreq_t *p)
 {
     unsigned int size, event;
-    unsigned char buffer[12];
+    unsigned char buffer[16];
 
     if ( likely(!tb_init_done) )
         return;
@@ -47,8 +47,11 @@ static void hvmtrace_io_assist(const ioreq_t *p)
 
     if ( !p->data_is_ptr )
     {
-        *(uint32_t *)&buffer[size] = p->data;
-        size += 4;
+        if ( size == 4 )
+            *(uint32_t *)&buffer[size] = p->data;
+        else
+            *(uint64_t *)&buffer[size] = p->data;
+        size *= 2;
     }
 
     trace_var(event, 0/*!cycles*/, size, buffer);