From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751777Ab1IMJvX (ORCPT ); Tue, 13 Sep 2011 05:51:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43332 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751308Ab1IMJvW (ORCPT ); Tue, 13 Sep 2011 05:51:22 -0400 Message-ID: <4E6F2790.4020602@redhat.com> Date: Tue, 13 Sep 2011 12:51:12 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0 MIME-Version: 1.0 To: Xiao Guangrong CC: Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH v3 01/11] KVM: MMU: avoid pte_list_desc running out in kvm_mmu_pte_write References: <4E5C4C20.3000403@cn.fujitsu.com> In-Reply-To: <4E5C4C20.3000403@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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). -- error compiling committee.c: too many arguments to function