Re: [Xen-devel] [PATCH 3/5] x86/pv: Break handle_ldt_mapping_fault() out of handle_gdt_ldt_mapping_fault()

[Doug Goldstein <cardoe@xxxxxxxxxx>]

On 1/12/18 12:37 PM, Andrew Cooper wrote:
> Adjust handle_ldt_mapping_fault() exclude the use of this fixup path for
> non-PV guests.  Well-formed code shouldn't reference the LDT while in HVM vcpu
> context, but currently on a context switch from PV to HVM context, there may
> be a stale LDT selector loaded, over an unmapped region.
> 
> By explicitly excluding HVM context at this point, we avoid erroneous
> hypervisor execution resulting in a cascade failure, by falling into
> pv_map_ldt_shadow_page().
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Obviously a behavior change here but the rationale behind it seems clear
to me and well worth doing for the net positive result:

Reviewed-by: Doug Goldstein <cardoe@xxxxxxxxxx>

-- 
Doug Goldstein

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