On Thursday 30 December 2010 17:14:23 Avi Kivity wrote:
> 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.
I think kvm_mmu_reset_context() in kvm_set_cr0() should cover this?
--
regards
Yang, Sheng
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