Re: [PATCH][GIT PULL][v3.3] x86: Test saved %rip in NMI todetermine nested NMI

[Steven Rostedt]

On Sun, 2012-02-19 at 12:45 -0800, H. Peter Anvin wrote:

> User space can change %cs, but it can never set it to __KERNEL_CS; 
> specifically user space can never set the bottom two bits in CS to zero.
> 
> So this should be a better test.

Great! That means that my original patch (the one never submitted, but
tested) would be the best.

Ingo,

I'll send out another pull request with the old patch. I'll still run it
through tests just to be sure, so it may take a day before I send it.

(I hope I still have it)

> 
> (Now, doing the test that way plays havoc with the braindamage knows as 
> Xen paravirt, but I don't think it's subject to this particular NMI code.)

Xen paravirt shouldn't be doing nested NMIs. I hope :-)

-- Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/