Re: [PATCH] KVM: VMX: Fix 32bit Windows blue screen with EPT

[Avi Kivity <avi@redhat.com>]

On 12/30/2010 11:05 AM, Sheng Yang wrote:
> >
> >  >    	if (!(cr0&   X86_CR0_PG)) {
> >  >    	
> >  >    		/* From paging/starting to nonpaging */
> >  >    		vmcs_write32(CPU_BASED_VM_EXEC_CONTROL,
> >  >
> >  >  @@ -1937,11 +1936,8 @@ static void ept_update_paging_mode_cr0(unsigned
> >  >  long *hw_cr0,
> >  >
> >  >    			vmcs_read32(CPU_BASED_VM_EXEC_CONTROL)&
> >  >    			
> >  >    			~(CPU_BASED_CR3_LOAD_EXITING |
> >  >    			
> >  >    			CPU_BASED_CR3_STORE_EXITING));
> >  >
> >  >  -		/* Must fetch cr3 before updating cr0 */
> >  >  -		cr3 = kvm_read_cr3(vcpu);
> >  >
> >  >    		vcpu->arch.cr0 = cr0;
> >  >    		vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
> >  >
> >  >  -		vmx_set_cr3(vcpu, cr3);
> >
> >  This is indeed bogus.  But what ensures that we'll have the correct
> >  GUEST_CR3 after enabling paging?
>
> In fact I don't understand why we need this line. All modification is for CR3
> reading, why we need to set hardware CR3 again? It should be the same as when we
> don't have CR3 accessor I think.

when cr0.pg=0 then we set GUEST_CR3=identity_pagetable.  We don't want 
that when we we switch to paging mode.

-- 
error compiling committee.c: too many arguments to function