[Xen-devel] AMD VMMCALL and VM86 mode

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Hello,

While working on XSA-192, I found a curious thing.  On AMD hardware, the
VMMCALL instruction appears to behave like a nop if executed in VM86
mode.  All other processor modes work fine.

The documentation suggests it should be valid in any situation, but I
never get a #VMEXIT from it.  Thus, I would have thought it would fall
into the un-intercepted category and raise a #UD fault, but I don't get
that either.

Is this behaviour expected?  The documentation would certainly seem to
indicate not.

~Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel