Re: [PATCH 2/4] xen/lowlevel: Implement pvop call for load_idt (sidt).

From: H. Peter Anvin
Date: Wed Oct 17 2012 - 19:51:28 EST

On 10/17/2012 06:49 AM, Konrad Rzeszutek Wilk wrote:
In the past it used to point to 'sidt' (native_store_idt) operation
which is a non-privileged operation. This resulted in the
'struct desc_ptr' value containing the address of Xen's IDT table,
instead of the IDT table that Linux thinks its using. The end result
is that doing:


would blow up b/c xen_load_idt would try to parse the IDT contents
(desc) and de-reference a virtual address that is outside Linux's
__va (it is in Xen's virtual address).

With this patch we are providing the last written IDT address.

OK... this seems like another excellent set of pvops calls that should be nukable to Kingdom Come. There is no reason, ever, to read the IDT and GDT from the kernel... the kernel already knows what they should be!


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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