From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takuya Yoshikawa Subject: Re: [PATCH 06/10] KVM: x86: MMU: Consolidate WARN_ON/BUG_ON checks for reverse-mapped sptes Date: Mon, 16 Nov 2015 12:34:43 +0900 Message-ID: <56494ED3.20301@lab.ntt.co.jp> References: <20151112204849.ba920599a8426d7196a0df73@lab.ntt.co.jp> <20151112205343.61fbcc0a911e891b1ddc8f19@lab.ntt.co.jp> <20151113220819.GA30105@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: pbonzini@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Marcelo Tosatti Return-path: In-Reply-To: <20151113220819.GA30105@amt.cnet> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 2015/11/14 7:08, Marcelo Tosatti wrote: > On Thu, Nov 12, 2015 at 08:53:43PM +0900, Takuya Yoshikawa wrote: >> At some call sites of rmap_get_first() and rmap_get_next(), BUG_ON is >> placed right after the call to detect unrelated sptes which must not be >> found in the reverse-mapping list. >> >> Move this check in rmap_get_first/next() so that all call sites, not >> just the users of the for_each_rmap_spte() macro, will be checked the >> same way. In addition, change the BUG_ON to WARN_ON since killing the >> whole host is the last thing that KVM should try. > > It should be a BUG_ON, if KVM continues it will corrupt (more) memory. In the sense that we cannot predict what kind of corruption it will cause, I agree with you. But if it can only corrupt that guest's memory, it is a bit sad to kill unrelated guests, and host, too. Anyway, since we cannot say for sure what a possible bug can cause, I agree with you now. Thanks, Takuya