On 04/12/2010 01:42 PM, Xiao Guangrong wrote:
Hi Avi,

Thanks for your comments.

Avi Kivity wrote:

Later we have:

         kvm_x86_ops->set_cr4(vcpu, cr4);
         vcpu->arch.cr4 = cr4;
         vcpu->arch.mmu.base_role.cr4_pge = (cr4&  X86_CR4_PGE)&&
!tdp_enabled;
All of which depend on cr4.
Oh, destroy_kvm_mmu() is not really destroyed cr3 and we can reload it later
form shadow page cache, so, maybe this patch is unnecessary.

But, i have a another question here, why we need encode 'cr4&  X86_CR4_PGE' into
base_role.cr4_gpe? Why we need allocation different shadow page for global page
and no-global page?

See 6364a3918cb. It was reverted later due to a problem with the implementation. I'm not sure whether I want to fix the bug and restore that patch, or to drop it altogether and give the guest ownership of cr4.pge. See cr4_guest_owned_bits (currently only used on ept).

As i know, global page is not static in TLB, and x86 cpu also may flush them 
form TLB,
maybe we no need treat global page specially... Am i miss something? :-(

You can't read reverted patches? :)

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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