| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] x86 instruction emulation in hvm
Yup. Not only did hvm_get_segment_register() work like a charm, but I
also ran into another problem as you have foretold.
The instruction is fxsave, which uses a mask to copy some CPU
information to a 512byte memory. Any chance of an emulation function
for this instruction?
As a side note, I know of quite a few research papers that mention
emulating memory writes to pages, some using Xen. This leads me to
believe that the problem of emulating most of these functions should
have been solved. I know it's not relevant for Xen production code, but
I'm wondering if there is a full emulator (perhaps QEMU?) inside Xen
that I can switch to instead of trying to add these functionalities in
an ad-hoc manner?
John
Keir Fraser wrote:
On 07/05/2009 20:39, "Emre Can Sezer" <ecsezer@xxxxxxxx> wrote:
I'm running an HVM guest using shadow page tables on a 64bit machine.
I'm working on a project where I mark certain pages read-only and
capture the writes into these pages. I then try to emulate the write
instructions using x86_emulate as is done in arch/x86/mm/shadow/multi.c.
The instruction I'm trying to emulate is:
asm("mov %%gs,%0" : "=m" (p->thread.gsindex));
Since the source operand is a segment register, and the x86_emulate_ops
structure that is being used does not have a ops->read_segment function
defined, the emulation fails.
Is there an easy way to add or activate this functionality? Perhaps a
full emulator, since one would expect to see other cases of memory
writes that are not handled as well.
Easily implemented -- you pass through to hvm_get_segment_register(). My
guess is you'll quickly fault on another instruction which is not so easily
fixed up, however.
-- Keir
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home