On 01/14/2010 09:41 PM, Marcelo Tosatti wrote:
Exit the guest pagetable walk loop if reading gpte failed. Otherwise its possible to enter an endless loop processing the previous present pte. Cc: stable@xxxxxxxxxx Signed-off-by: Marcelo Tosatti<mtosatti@xxxxxxxxxx> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 58a0f1e..ede2131 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -150,7 +150,9 @@ walk: walker->table_gfn[walker->level - 1] = table_gfn; walker->pte_gpa[walker->level - 1] = pte_gpa; - kvm_read_guest(vcpu->kvm, pte_gpa,&pte, sizeof(pte)); + if (kvm_read_guest(vcpu->kvm, pte_gpa,&pte, sizeof(pte))) + goto not_present; +
On real hardware, if you place a pte at non-existing memory, you aren't guaranteed to get the present bit clear, so why is this necessary?
We should be able to survive any garbage the pte previously contained. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
