From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ACD9AC4320A for ; Mon, 2 Aug 2021 12:58:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E0CB60FC4 for ; Mon, 2 Aug 2021 12:58:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233810AbhHBM6m (ORCPT ); Mon, 2 Aug 2021 08:58:42 -0400 Received: from 8bytes.org ([81.169.241.247]:52982 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232629AbhHBM6m (ORCPT ); Mon, 2 Aug 2021 08:58:42 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id 9AD29379; Mon, 2 Aug 2021 14:58:30 +0200 (CEST) Date: Mon, 2 Aug 2021 14:58:26 +0200 From: Joerg Roedel To: Tianyu Lan Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, will@kernel.org, davem@davemloft.net, kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, arnd@arndb.de, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, ardb@kernel.org, Tianyu.Lan@microsoft.com, rientjes@google.com, martin.b.radev@gmail.com, akpm@linux-foundation.org, rppt@kernel.org, kirill.shutemov@linux.intel.com, aneesh.kumar@linux.ibm.com, krish.sadhukhan@oracle.com, saravanand@fb.com, xen-devel@lists.xenproject.org, pgonda@google.com, david@redhat.com, keescook@chromium.org, hannes@cmpxchg.org, sfr@canb.auug.org.au, michael.h.kelley@microsoft.com, iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, netdev@vger.kernel.org, vkuznets@redhat.com, anparri@microsoft.com Subject: Re: [PATCH 07/13] HV/Vmbus: Add SNP support for VMbus channel initiate message Message-ID: References: <20210728145232.285861-1-ltykernel@gmail.com> <20210728145232.285861-8-ltykernel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210728145232.285861-8-ltykernel@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Wed, Jul 28, 2021 at 10:52:22AM -0400, Tianyu Lan wrote: > + if (hv_is_isolation_supported()) { > + vmbus_connection.monitor_pages_va[0] > + = vmbus_connection.monitor_pages[0]; > + vmbus_connection.monitor_pages[0] > + = memremap(msg->monitor_page1, HV_HYP_PAGE_SIZE, > + MEMREMAP_WB); > + if (!vmbus_connection.monitor_pages[0]) > + return -ENOMEM; > + > + vmbus_connection.monitor_pages_va[1] > + = vmbus_connection.monitor_pages[1]; > + vmbus_connection.monitor_pages[1] > + = memremap(msg->monitor_page2, HV_HYP_PAGE_SIZE, > + MEMREMAP_WB); > + if (!vmbus_connection.monitor_pages[1]) { > + memunmap(vmbus_connection.monitor_pages[0]); > + return -ENOMEM; > + } > + > + memset(vmbus_connection.monitor_pages[0], 0x00, > + HV_HYP_PAGE_SIZE); > + memset(vmbus_connection.monitor_pages[1], 0x00, > + HV_HYP_PAGE_SIZE); > + } Okay, let me see if I got this right. In Hyper-V Isolation VMs, when the guest wants to make memory shared, it does": - Call to the Hypervisor the mark the pages shared. The Hypervisor will do the RMP update and remap the pages at (VTOM + pa) - The guest maps the memory again into its page-table, so that the entries point to the correct GPA (which is above VTOM now). Or in other words, Hyper-V implements a hardware-independent and configurable c-bit position, as the VTOM value is always power-of-two aligned. Is that correct? This would at least explain why there is no separate allocation/dealloction of memory for the shared range. Thanks, Joerg