RE: [Xen-devel] Why CR0.WP is always set in HVM domain

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

Not sure if we can use shadow_mode_trap_reads(), i.e. when WP is clear,
we set all user space mapping to guest page table to be non-present. And
then do emulate in shadow for such situation. But seems
shadow_mode_traps_reads not implemented yet :(

-- Yunhong 


xen-devel-bounces@xxxxxxxxxxxxxxxxxxx <> wrote:
> Thanks for your explaination.
> I notice some anti-virus application clear CR0.WP, so maybe we need to
> consider this support. 
> 
> -- Yunhong
> 
> xen-devel-bounces@xxxxxxxxxxxxxxxxxxx <> wrote:
>> It's necessary because we need to trap guest writes to pagetables,
>> regardless of setting of guest CR0.WP. If it turns out we need
>> to properly
>> emulate CR0.WP then we'll need to come up with a scheme that does not
>> require us to run the guest with real CR0.WP set. Possibly it
>> will require
>> us to emulate certain memory accesses.
>> 
>> -- Keir
>> 
>> On 8/11/07 14:23, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:
>> 
>>> In "arch/x86/hvm/vmx/vmx.c", vmx_update_guest_cr(), the CR0.WP is
always
>>>         set as following code: v->arch.hvm_vcpu.hw_cr[0] =
>>>             v->arch.hvm_vcpu.guest_cr[0] |
>>>             X86_CR0_PE | X86_CR0_NE | X86_CR0_PG | X86_CR0_WP;
>>> 
>>> I'm wondering are there any special reason for this? I try to check
>>> shadow code and didn't find any clue.
>>> Can anyone give me some hints?
>>> 
>>> Thanks
>>> Yunhong Jiang
>>> 
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>> http://lists.xensource.com/xen-devel
>> 
>> 
>> 
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> 
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