From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50468) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UzU09-0007U2-U6 for qemu-devel@nongnu.org; Wed, 17 Jul 2013 11:50:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UzU08-0000L5-BG for qemu-devel@nongnu.org; Wed, 17 Jul 2013 11:50:49 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:52745) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UzU08-0000Ky-5F for qemu-devel@nongnu.org; Wed, 17 Jul 2013 11:50:48 -0400 Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 17 Jul 2013 09:50:46 -0600 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id B52CDC9004A for ; Wed, 17 Jul 2013 11:50:41 -0400 (EDT) Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r6HFoddn131350 for ; Wed, 17 Jul 2013 11:50:40 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r6HFoZsJ023966 for ; Wed, 17 Jul 2013 11:50:35 -0400 From: Anthony Liguori In-Reply-To: <51E67B7A.8000800@redhat.com> References: <1373840171-25556-1-git-send-email-rth@twiddle.net> <1373840171-25556-4-git-send-email-rth@twiddle.net> <8761w9wm50.fsf@blackfin.pond.sub.org> <51E67B7A.8000800@redhat.com> Date: Wed, 17 Jul 2013 10:50:31 -0500 Message-ID: <8761w9gp88.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: Re: [Qemu-devel] [PULL 3/5] exec: Support 64-bit operations in address_space_rw List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Markus Armbruster Cc: Gerd Hoffmann , qemu-devel@nongnu.org, Richard Henderson Paolo Bonzini writes: > Il 17/07/2013 11:50, Markus Armbruster ha scritto: >> Richard Henderson writes: >> >>> Honor the implementation maximum access size, and at least check >>> the minimum access size. >>> >>> Reviewed-by: Paolo Bonzini >>> Signed-off-by: Richard Henderson >> >> Fails for me: >> >> qemu-system-x86_64: /work/armbru/qemu/exec.c:1927: memory_access_size: Assertion `l >= access_size_min' failed. > > This: > > unsigned access_size_min = mr->ops->impl.min_access_size; > unsigned access_size_max = mr->ops->impl.max_access_size; > > must be respectively: > > unsigned access_size_min = 1; > unsigned access_size_max = mr->ops->valid.max_access_size; > > access_size_min can be 1 because erroneous accesses must not crash > QEMU, they should trigger exceptions in the guest or just return > garbage (depending on the CPU). I'm not sure I understand the comment, > placing a 4-byte field at the last byte of a region makes no sense > (unless impl.unaligned is true). > > access_size_max can be mr->ops->valid.max_access_size because memory.c > can and will still break accesses bigger than > mr->ops->impl.max_access_size. > > Markus, can you try the minimal patch above? Or this one that also > does the consequent simplifications. FYI, the reproducer is very simple: qemu-system-x86_64 -usb Regards, Anthony Liguori > > diff --git a/exec.c b/exec.c > index c99a883..0904283 100644 > --- a/exec.c > +++ b/exec.c > @@ -1898,14 +1898,8 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write) > > static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr) > { > - unsigned access_size_min = mr->ops->impl.min_access_size; > - unsigned access_size_max = mr->ops->impl.max_access_size; > + unsigned access_size_max = mr->ops->valid.max_access_size; > > - /* Regions are assumed to support 1-4 byte accesses unless > - otherwise specified. */ > - if (access_size_min == 0) { > - access_size_min = 1; > - } > if (access_size_max == 0) { > access_size_max = 4; > } > @@ -1922,9 +1916,6 @@ static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr) > if (l > access_size_max) { > l = access_size_max; > } > - /* ??? The users of this function are wrong, not supporting minimums larger > - than the remaining length. C.f. memory.c:access_with_adjusted_size. */ > - assert(l >= access_size_min); > > return l; > } > > Paolo