From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50378) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1evqNw-00067C-7C for qemu-devel@nongnu.org; Tue, 13 Mar 2018 16:19:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1evqNt-0004MY-0j for qemu-devel@nongnu.org; Tue, 13 Mar 2018 16:19:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54964) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1evqNs-0004Lz-Or for qemu-devel@nongnu.org; Tue, 13 Mar 2018 16:18:56 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 19D5228203 for ; Tue, 13 Mar 2018 20:18:56 +0000 (UTC) From: Alex Williamson Date: Tue, 13 Mar 2018 14:18:52 -0600 Message-ID: <20180313201852.2327.45170.stgit@gimli.home> In-Reply-To: <20180313201415.2327.62402.stgit@gimli.home> References: <20180313201415.2327.62402.stgit@gimli.home> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [PULL 09/11] vfio/pci: Relax DMA map errors for MMIO regions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org From: Alexey Kardashevskiy At the moment if vfio_memory_listener is registered in the system memory address space, it maps/unmaps every RAM memory region for DMA. It expects system page size aligned memory sections so vfio_dma_map would not fail and so far this has been the case. A mapping failure would be fatal. A side effect of such behavior is that some MMIO pages would not be mapped silently. However we are going to change MSIX BAR handling so we will end having non-aligned sections in vfio_memory_listener (more details is in the next patch) and vfio_dma_map will exit QEMU. In order to avoid fatal failures on what previously was not a failure and was just silently ignored, this checks the section alignment to the smallest supported IOMMU page size and prints an error if not aligned; it also prints an error if vfio_dma_map failed despite the page size check. Both errors are not fatal; only MMIO RAM regions are checked (aka "RAM device" regions). If the amount of errors printed is overwhelming, the MSIX relocation could be used to avoid excessive error output. This is unlikely to cause any behavioral change. Signed-off-by: Alexey Kardashevskiy [aw: Fix Int128 bit ops] Signed-off-by: Alex Williamson --- hw/vfio/common.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 49 insertions(+), 6 deletions(-) diff --git a/hw/vfio/common.c b/hw/vfio/common.c index 6a8203a53245..07c03d78b666 100644 --- a/hw/vfio/common.c +++ b/hw/vfio/common.c @@ -544,18 +544,40 @@ static void vfio_listener_region_add(MemoryListener *listener, llsize = int128_sub(llend, int128_make64(iova)); + if (memory_region_is_ram_device(section->mr)) { + hwaddr pgmask = (1ULL << ctz64(hostwin->iova_pgsizes)) - 1; + + if ((iova & pgmask) || (int128_get64(llsize) & pgmask)) { + error_report("Region 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx + " is not aligned to 0x%"HWADDR_PRIx + " and cannot be mapped for DMA", + section->offset_within_region, + int128_getlo(section->size), + pgmask + 1); + return; + } + } + ret = vfio_dma_map(container, iova, int128_get64(llsize), vaddr, section->readonly); if (ret) { error_report("vfio_dma_map(%p, 0x%"HWADDR_PRIx", " "0x%"HWADDR_PRIx", %p) = %d (%m)", container, iova, int128_get64(llsize), vaddr, ret); + if (memory_region_is_ram_device(section->mr)) { + /* Allow unexpected mappings not to be fatal for RAM devices */ + return; + } goto fail; } return; fail: + if (memory_region_is_ram_device(section->mr)) { + error_report("failed to vfio_dma_map. pci p2p may not work"); + return; + } /* * On the initfn path, store the first error in the container so we * can gracefully fail. Runtime, there's not much we can do other @@ -577,6 +599,7 @@ static void vfio_listener_region_del(MemoryListener *listener, hwaddr iova, end; Int128 llend, llsize; int ret; + bool try_unmap = true; if (vfio_listener_skipped_section(section)) { trace_vfio_listener_region_del_skip( @@ -629,14 +652,34 @@ static void vfio_listener_region_del(MemoryListener *listener, trace_vfio_listener_region_del(iova, end); - ret = vfio_dma_unmap(container, iova, int128_get64(llsize)); - memory_region_unref(section->mr); - if (ret) { - error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " - "0x%"HWADDR_PRIx") = %d (%m)", - container, iova, int128_get64(llsize), ret); + if (memory_region_is_ram_device(section->mr)) { + hwaddr pgmask; + VFIOHostDMAWindow *hostwin; + bool hostwin_found = false; + + QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) { + if (hostwin->min_iova <= iova && end <= hostwin->max_iova) { + hostwin_found = true; + break; + } + } + assert(hostwin_found); /* or region_add() would have failed */ + + pgmask = (1ULL << ctz64(hostwin->iova_pgsizes)) - 1; + try_unmap = !((iova & pgmask) || (int128_get64(llsize) & pgmask)); + } + + if (try_unmap) { + ret = vfio_dma_unmap(container, iova, int128_get64(llsize)); + if (ret) { + error_report("vfio_dma_unmap(%p, 0x%"HWADDR_PRIx", " + "0x%"HWADDR_PRIx") = %d (%m)", + container, iova, int128_get64(llsize), ret); + } } + memory_region_unref(section->mr); + if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) { vfio_spapr_remove_window(container, section->offset_within_address_space);