From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40377) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e36C5-0007Dd-TF for qemu-devel@nongnu.org; Fri, 13 Oct 2017 16:04:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e36C2-0008Kc-Q3 for qemu-devel@nongnu.org; Fri, 13 Oct 2017 16:04:29 -0400 Received: from mail-pf0-x22c.google.com ([2607:f8b0:400e:c00::22c]:55389) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1e36C2-0008JD-Jl for qemu-devel@nongnu.org; Fri, 13 Oct 2017 16:04:26 -0400 Received: by mail-pf0-x22c.google.com with SMTP id 17so11180829pfn.12 for ; Fri, 13 Oct 2017 13:04:26 -0700 (PDT) References: <20171013181913.7556-1-Andrew.Baumann@microsoft.com> From: Richard Henderson Message-ID: <669d753c-fa83-8f0a-c366-37f468e9e502@linaro.org> Date: Fri, 13 Oct 2017 13:04:22 -0700 MIME-Version: 1.0 In-Reply-To: <20171013181913.7556-1-Andrew.Baumann@microsoft.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] notdirty_mem_write: implement 8-byte accesses List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andrew Baumann , qemu-devel@nongnu.org Cc: Peter Crosthwaite , Paolo Bonzini On 10/13/2017 11:19 AM, Andrew Baumann wrote: > Aligned 8-byte memory writes by a 64-bit target on a 64-bit host should > always turn into atomic 8-byte writes on the host, however if we missed > in the softmmu, and the TLB line was marked as not dirty, then we > would end up tearing the 8-byte write into two 4-byte writes in > access_with_adjusted_size(). > > Signed-off-by: Andrew Baumann > --- > This manifested as a race in lock-free synchronisation with an aarch64 > Windows guest on an x86-64 host (with multithreaded TCG). Reviewed-by: Richard Henderson r~