From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48257) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YIfJI-0000Ye-T2 for qemu-devel@nongnu.org; Tue, 03 Feb 2015 10:22:44 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YIfJF-0004zk-L3 for qemu-devel@nongnu.org; Tue, 03 Feb 2015 10:22:40 -0500 Received: from mail-wi0-x22c.google.com ([2a00:1450:400c:c05::22c]:54556) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YIfJF-0004ze-Dg for qemu-devel@nongnu.org; Tue, 03 Feb 2015 10:22:37 -0500 Received: by mail-wi0-f172.google.com with SMTP id h11so25128927wiw.5 for ; Tue, 03 Feb 2015 07:22:36 -0800 (PST) Sender: Paolo Bonzini Message-ID: <54D0E7B8.2060501@redhat.com> Date: Tue, 03 Feb 2015 16:22:32 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1422965498-11500-1-git-send-email-thuth@linux.vnet.ibm.com> <1422965498-11500-2-git-send-email-thuth@linux.vnet.ibm.com> <54D0C76B.70603@redhat.com> <20150203161601.1319f7ef@oc7435384737.ibm.com> In-Reply-To: <20150203161601.1319f7ef@oc7435384737.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH RFC 1/1] KVM: s390: Add MEMOP ioctl for reading/writing guest memory List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth Cc: cornelia.huck@de.ibm.com, borntraeger@de.ibm.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, agraf@suse.de On 03/02/2015 16:16, Thomas Huth wrote: > Actually, I'd prefer to keep the "virtual" in the defines for the type > of operation below: When it comes to s390 storage keys, we likely might > need some calls for reading and writing to physical memory, too. Then > we could simply extend this ioctl instead of inventing a new one. Can you explain why it is necessary to read/write physical addresses from user space? In the case of QEMU, I'm worried that you would have to invent your own memory read/write APIs that are different from everything else. On real s390 zPCI, does bus-master DMA update storage keys? >> Not really true, as you don't check it. So "It is not used by KVM with >> the currently defined set of flags" is a better explanation. > > ok ... and maybe add "should be set to zero" ? If you don't check it, it is misleading to document this. Paolo