From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44271) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1abWFh-0003dy-Jv for qemu-devel@nongnu.org; Thu, 03 Mar 2016 11:37:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1abWFe-0001vW-EV for qemu-devel@nongnu.org; Thu, 03 Mar 2016 11:37:25 -0500 References: <1456941872-8791-1-git-send-email-afarallax@yandex.ru> <56D73CB6.7040702@gmail.com> <56D84EB5.30808@gmail.com> From: Sergey Fedorov Message-ID: <56D8683D.1080004@gmail.com> Date: Thu, 3 Mar 2016 19:37:17 +0300 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-arm] [PATCH] target-arm: Fix translation level on early translation faults List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Sergey Sorokin , qemu-arm , QEMU Developers On 03.03.2016 17:55, Peter Maydell wrote: > On 3 March 2016 at 14:48, Sergey Fedorov wrote: >> On 03.03.2016 16:49, Peter Maydell wrote: >>> On 2 March 2016 at 19:19, Sergey Fedorov wrote: >>>> On 02.03.2016 21:04, Sergey Sorokin wrote: >>>>> Qemu reports translation fault on 1st level instead of 0th level in case of >>>>> AArch64 address translation if the translation table walk is disabled or >>>>> the address is in the gap between the two regions. >>>> It's probably not a very clear description in the commit message. IIUC, >>>> level 0 fault is reported in case of any fault from TTBR in AArch64 state. >>> Yes (though you mean "under an AArch64 translation regime"). Conversely, the >>> only fault reported at level 0 under an AArch32 translation regime is >>> the AddressSize fault (for bad addresses in TTBR0/1), which we don't >>> currently implement. >>> >>> There's also a code path later in the function that does >>> level = va_size == 64 ? 0 : 1; >>> >>> but I'm not sure it's worth rearranging that code to avoid the >>> duplication of "what level do we report this kind of fault at?". >> Right, but actually I think this patch is going to fix the two "goto >> do_fault" cases which can happen before this "level = va_size == 64 ? 0 >> : 1", namely the EDP check and the check for virtual address which is in >> the gap between TTBR0 and TTBR1 regions. > Yes, this patch is definitely fixing a bug; I'm just mentioning that other > code path because it seems to be the result of previously fixing the bug > for a particular special case... > > Ah, right, I think I understand you :) So we'd better remove these lines: /* AArch64 reports these as level 0 faults. * AArch32 reports these as level 1 faults. */ level = va_size == 64 ? 0 : 1; fault_type = translation_fault; Kind regards, Sergey