kernel/linux.git/drivers/virtio/virtio_mem.c, branch linux-6.0.y

mm: use is_zone_movable_page() helper

2022-07-30T01:07:20+00:00

Use is_zone_movable_page() helper to simplify code. Link: https://lkml.kernel.org/r/20220726131135.146912-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Reviewed-by: David Hildenbrand Reviewed-by: Pankaj Gupta Acked-by: Jason Wang Signed-off-by: Andrew Morton

drivers: virtio_mem: use pageblock size as the minimum virtio_mem size.

2022-05-13T14:20:13+00:00

alloc_contig_range() now only needs to be aligned to pageblock_nr_pages, drop virtio_mem size requirement that it needs to be MAX_ORDER_NR_PAGES. Link: https://lkml.kernel.org/r/20220425143118.2850746-7-zi.yan@sent.com Signed-off-by: Zi Yan Cc: Christophe Leroy Cc: David Hildenbrand Cc: Eric Ren Cc: kernel test robot Cc: Mel Gorman Cc: Mike Rapoport Cc: Minchan Kim Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: enforce pageblock_order < MAX_ORDER

2022-03-22T22:57:06+00:00

Some places in the kernel don't really expect pageblock_order >= MAX_ORDER, and it looks like this is only possible in corner cases: 1) CONFIG_DEFERRED_STRUCT_PAGE_INIT we'll end up freeing pageblock_order pages via __free_pages_core(), which cannot possibly work. 2) find_zone_movable_pfns_for_nodes() will roundup the ZONE_MOVABLE start PFN to MAX_ORDER_NR_PAGES. Consequently with a bigger pageblock_order, we could have a single pageblock partially managed by two zones. 3) compaction code runs into __fragmentation_index() with order >= MAX_ORDER, when checking WARN_ON_ONCE(order >= MAX_ORDER). [1] 4) mm/page_reporting.c won't be reporting any pages with default page_reporting_order == pageblock_order, as we'll be skipping the reporting loop inside page_reporting_process_zone(). 5) __rmqueue_fallback() will never be able to steal with ALLOC_NOFRAGMENT. pageblock_order >= MAX_ORDER is weird either way: it's a pure optimization for making alloc_contig_range(), as used for allcoation of gigantic pages, a little more reliable to succeed. However, if there is demand for somewhat reliable allocation of gigantic pages, affected setups should be using CMA or boottime allocations instead. So let's make sure that pageblock_order < MAX_ORDER and simplify. [1] https://lkml.kernel.org/r/87r189a2ks.fsf@linux.ibm.com Link: https://lkml.kernel.org/r/20220214174132.219303-3-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Zi Yan Cc: Aneesh Kumar K.V Cc: Benjamin Herrenschmidt Cc: Christoph Hellwig Cc: Frank Rowand Cc: John Garry via iommu Cc: Marek Szyprowski Cc: Michael Ellerman Cc: Michael S. Tsirkin Cc: Minchan Kim Cc: Paul Mackerras Cc: Rob Herring Cc: Robin Murphy Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

virtio/virtio_mem: handle a possible NULL as a memcpy parameter

2022-01-14T23:50:53+00:00

There is a check for vm->sbm.sb_states before, and it should check it here as well. Signed-off-by: Peng Hao Link: https://lore.kernel.org/r/20211222011225.40573-1-flyingpeng@tencent.com Signed-off-by: Michael S. Tsirkin Fixes: 5f1f79bbc9e2 ("virtio-mem: Paravirtualized memory hotplug") Cc: stable@vger.kernel.org # v5.8+

virtio-mem: prepare fake page onlining code for granularity smaller than MAX_ORDER - 1

2022-01-14T23:50:52+00:00

Let's prepare our fake page onlining code for subblock size smaller than MAX_ORDER - 1: we might get called for ranges not covering properly aligned MAX_ORDER - 1 pages. We have to detect the order to use dynamically. Signed-off-by: David Hildenbrand Link: https://lore.kernel.org/r/20211126134209.17332-3-david@redhat.com Signed-off-by: Michael S. Tsirkin Reviewed-by: Zi Yan Reviewed-by: Eric Ren

virtio-mem: prepare page onlining code for granularity smaller than MAX_ORDER - 1

2022-01-14T23:50:52+00:00

Let's prepare our page onlining code for subblock size smaller than MAX_ORDER - 1: we'll get called for a MAX_ORDER - 1 page but might have some subblocks in the range plugged and some unplugged. In that case, fallback to subblock granularity to properly only expose the plugged parts to the buddy. Signed-off-by: David Hildenbrand Link: https://lore.kernel.org/r/20211126134209.17332-2-david@redhat.com Signed-off-by: Michael S. Tsirkin Reviewed-by: Zi Yan Reviewed-by: Eric Ren

virtio: wrap config->reset calls

2022-01-14T23:50:52+00:00

This will enable cleanups down the road. The idea is to disable cbs, then add "flush_queued_cbs" callback as a parameter, this way drivers can flush any work queued after callbacks have been disabled. Signed-off-by: Michael S. Tsirkin Link: https://lore.kernel.org/r/20211013105226.20225-1-mst@redhat.com Signed-off-by: Michael S. Tsirkin

virtio-mem: support VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE

2021-11-10T14:32:38+00:00

The initial virtio-mem spec states that while unplugged memory should not be read, the device still has to allow for reading unplugged memory inside the usable region. The primary motivation for this default handling was to simplify bringup of virtio-mem, because there were corner cases where Linux might have accidentially read unplugged memory inside added Linux memory blocks. In the meantime, we: 1. Removed /dev/kmem in commit bbcd53c96071 ("drivers/char: remove /dev/kmem for good") 2. Disallowed access to virtio-mem device memory via /dev/mem in commit 2128f4e21aa2 ("virtio-mem: disallow mapping virtio-mem memory via /dev/mem") 3. Sanitized access to virtio-mem device memory via /proc/kcore in commit 0daa322b8ff9 ("fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages") 4. Sanitized access to virtio-mem device memory via /proc/vmcore in commit ce2814622e84 ("virtio-mem: kdump mode to sanitize /proc/vmcore access") "Accidential" access to unplugged memory is no longer possible; we can support the new VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE feature that will be required by some hypervisors implementing virtio-mem in the near future. Acked-by: Michael S. Tsirkin Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: Marek Kedzierski Cc: Hui Zhu Cc: Sebastien Boeuf Cc: Pankaj Gupta Cc: Wei Yang Signed-off-by: David Hildenbrand

virtio-mem: disallow mapping virtio-mem memory via /dev/mem

2021-11-09T18:02:52+00:00

We don't want user space to be able to map virtio-mem device memory directly (e.g., via /dev/mem) in order to have guarantees that in a sane setup we'll never accidentially access unplugged memory within the device-managed region of a virtio-mem device, just as required by the virtio-spec. As soon as the virtio-mem driver is loaded, the device region is visible in /proc/iomem via the parent device region. From that point on user space is aware of the device region and we want to disallow mapping anything inside that region (where we will dynamically (un)plug memory) until the driver has been unloaded cleanly and e.g., another driver might take over. By creating our parent IORESOURCE_SYSTEM_RAM resource with IORESOURCE_EXCLUSIVE, we will disallow any /dev/mem access to our device region until the driver was unloaded cleanly and removed the parent region. This will work even though only some memory blocks are actually currently added to Linux and appear as busy in the resource tree. So access to the region from user space is only possible a) if we don't load the virtio-mem driver. b) after unloading the virtio-mem driver cleanly. Don't build virtio-mem if access to /dev/mem cannot be restricticted -- if we have CONFIG_DEVMEM=y but CONFIG_STRICT_DEVMEM is not set. Link: https://lkml.kernel.org/r/20210920142856.17758-4-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Dan Williams Acked-by: Michael S. Tsirkin Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Hanjun Guo Cc: Jason Wang Cc: "Rafael J. Wysocki" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

virtio-mem: kdump mode to sanitize /proc/vmcore access

2021-11-09T18:02:48+00:00

Although virtio-mem currently supports reading unplugged memory in the hypervisor, this will change in the future, indicated to the device via a new feature flag. We similarly sanitized /proc/kcore access recently. [1] Let's register a vmcore callback, to allow vmcore code to check if a PFN belonging to a virtio-mem device is either currently plugged and should be dumped or is currently unplugged and should not be accessed, instead mapping the shared zeropage or returning zeroes when reading. This is important when not capturing /proc/vmcore via tools like "makedumpfile" that can identify logically unplugged virtio-mem memory via PG_offline in the memmap, but simply by e.g., copying the file. Distributions that support virtio-mem+kdump have to make sure that the virtio_mem module will be part of the kdump kernel or the kdump initrd; dracut was recently [2] extended to include virtio-mem in the generated initrd. As long as no special kdump kernels are used, this will automatically make sure that virtio-mem will be around in the kdump initrd and sanitize /proc/vmcore access -- with dracut. With this series, we'll send one virtio-mem state request for every ~2 MiB chunk of virtio-mem memory indicated in the vmcore that we intend to read/map. In the future, we might want to allow building virtio-mem for kdump mode only, even without CONFIG_MEMORY_HOTPLUG and friends: this way, we could support special stripped-down kdump kernels that have many other config options disabled; we'll tackle that once required. Further, we might want to try sensing bigger blocks (e.g., memory sections) first before falling back to device blocks on demand. Tested with Fedora rawhide, which contains a recent kexec-tools version (considering "System RAM (virtio_mem)" when creating the vmcore header) and a recent dracut version (including the virtio_mem module in the kdump initrd). Link: https://lkml.kernel.org/r/20210526093041.8800-1-david@redhat.com [1] Link: https://github.com/dracutdevs/dracut/pull/1157 [2] Link: https://lkml.kernel.org/r/20211005121430.30136-10-david@redhat.com Signed-off-by: David Hildenbrand Cc: Baoquan He Cc: Borislav Petkov Cc: Boris Ostrovsky Cc: Dave Young Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jason Wang Cc: Juergen Gross Cc: "Michael S. Tsirkin" Cc: Michal Hocko Cc: Mike Rapoport Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Stefano Stabellini Cc: Thomas Gleixner Cc: Vivek Goyal Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds