From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: [PATCH v6 00/12] KVM: introduce readonly memslot Date: Tue, 21 Aug 2012 10:57:01 +0800 Message-ID: <5032F8FD.2020306@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Avi Kivity Return-path: Received: from e28smtp02.in.ibm.com ([122.248.162.2]:49415 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755027Ab2HUC5L (ORCPT ); Mon, 20 Aug 2012 22:57:11 -0400 Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 21 Aug 2012 08:27:07 +0530 Sender: kvm-owner@vger.kernel.org List-ID: Changelog: - fix endless retrying for unhandleable instruction which accesses on readonly host memory - divide slot->flags by 16:16, the lower part is visible for userspace, the reset is internally used in kvm, and document this in the code - check slot->flags for gfn_to_hva_memslot The test case can be found at: http://lkml.indiana.edu/hypermail/linux/kernel/1207.2/00819/migrate-perf.tar.bz2 In current code, if we map a readonly memory space from host to guest and the page is not currently mapped in the host, we will get a fault-pfn and async is not allowed, then the vm will crash. As Avi's suggestion, We introduce readonly memory region to map ROM/ROMD to the guest, read access is happy for readonly memslot, write access on readonly memslot will cause KVM_EXIT_MMIO exit.