Re: [PATCH] KVM: MMU: Segregate mmu pages created with different cr4.pge settings

[Marcelo Tosatti <mtosatti@redhat.com>]

On Wed, Jan 07, 2009 at 01:32:41PM +0200, Avi Kivity wrote:
> Marcelo Tosatti wrote:
>> Let me shoot at one direction: a shadow page with PGE bit in either
>> state is created. Later that shadow page is nuked (via mmu notifiers,
>> for example). 
>
> I doubt that mmu notifiers were invoked in this case (the bug would be  
> very rare); in any case we flush the tlb.

This comment is worrying

        /*
         * FIXME: Tis shouldn't be necessary here, but there is a flush
         * missing in the MMU code. Until we find this bug, flush the
         * complete TLB here on an NPF
         */
        if (npt_enabled)
                svm_flush_tlb(&svm->vcpu);

Alexander, you might want to try this patch, -ENONPT here (and revert the previous
one). I have no clue, what else could be causing this?

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 10bdb2a..bf68e5b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -33,6 +33,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 #include <asm/vmx.h>
+#include <asm/tlbflush.h>
 
 /*
  * When setting this variable to true it enables Two-Dimensional-Paging
@@ -1850,6 +1851,11 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
 
 		if (*iterator.sptep == shadow_trap_nonpresent_pte) {
 			pseudo_gfn = (iterator.addr & PT64_DIR_BASE_ADDR_MASK) >> PAGE_SHIFT;
+
+                        kvm_flush_remote_tlbs(vcpu->kvm);
+                        kvm_mmu_flush_tlb(vcpu);
+                        __flush_tlb();
+                        
 			sp = kvm_mmu_get_page(vcpu, pseudo_gfn, iterator.addr,
 					      iterator.level - 1,
 					      1, ACC_ALL, iterator.sptep);