On 09/13/2011 05:51 PM, Avi Kivity wrote: > On 08/30/2011 05:34 AM, Xiao Guangrong wrote: >> kvm_mmu_pte_write is unsafe since we need to alloc pte_list_desc in the >> function when spte is prefetched, unfortunately, we can not know how many >> spte need to be prefetched on this path, that means we can use out of the >> free pte_list_desc object in the cache, and BUG_ON() is triggered, also some >> path does not fill the cache, such as INS instruction emulated that does not >> trigger page fault >> >> @@ -3716,10 +3735,6 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code, >> goto out; >> } >> >> - r = mmu_topup_memory_caches(vcpu); >> - if (r) >> - goto out; >> - >> er = x86_emulate_instruction(vcpu, cr2, 0, insn, insn_len); >> > > Suppose we are out of memory, can't this get us in an endless loop? > > return -ENOMEM breaks as out (and kills the guest, likely). > If memory is not enough, we just clear sptes on pte_write path(not prefetch spte), the later page fault path can return -1 to let guest crash. Hmm? -- 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
