From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH RFC 1/1] KVM: s390: Add MEMOP ioctl for reading/writing guest memory Date: Tue, 03 Feb 2015 16:22:32 +0100 Message-ID: <54D0E7B8.2060501@redhat.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: cornelia.huck@de.ibm.com, borntraeger@de.ibm.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, agraf@suse.de To: Thomas Huth Return-path: Received: from mail-wg0-f51.google.com ([74.125.82.51]:35502 "EHLO mail-wg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965929AbbBCPWi (ORCPT ); Tue, 3 Feb 2015 10:22:38 -0500 Received: by mail-wg0-f51.google.com with SMTP id k14so45103758wgh.10 for ; Tue, 03 Feb 2015 07:22:36 -0800 (PST) In-Reply-To: <20150203161601.1319f7ef@oc7435384737.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: 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