Re: [Xen-devel] [PATCH] ignore guest writes to read only memory regions or memory holes in EPT

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 26/10/2009 08:45, "Li, Xin" <xin.li@xxxxxxxxx> wrote:

>> ignore guest writes to read only memory regions or memory holes in EPT.
> 
> Keir,
> For reads from memory holes, hw returns a value with all bits set. Xen should
> emulate this behavior, and this needs to change Xen x86 instruction emulation
> code. do we already have such logic in Xen?
> 
> In early days, such reads were sent to Qemu, which returns 0xFFFFFFFF, 0xFFFF
> or 0xFF.

I think we should already handle this correctly with the existing
handle_mmio() case in ept_handle_violation(). The read should indeed go to
qemu which should do the right thing.

But also see my previous email about simplifying and robustifying
ept_handle_violation().

 -- Keir



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