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| * | | | | leds: aat1290: Fix module autoload for OF platform driverLuis de Bethencourt2015-09-17
| | |/ / / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This platform driver has a OF device ID table but the OF module alias information is not created so module autoloading won't work. Signed-off-by: Luis de Bethencourt <luis@debethencourt.com> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
* | | | | Merge tag 'for-linus' of ↵Linus Torvalds2015-09-19
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma Pull rdma fixes from Doug Ledford: "The new hfi1 driver in staging/rdma has had a number of fixup patches since being added to the tree. This is the first batch of those fixes" * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma: IB/hfi: Properly set permissions for user device files IB/hfi1: mask vs shift confusion IB/hfi1: clean up some defines IB/hfi1: info leak in get_ctxt_info() IB/hfi1: fix a locking bug IB/hfi1: checking for NULL instead of IS_ERR IB/hfi1: fix sdma_descq_cnt parameter parsing IB/hfi1: fix copy_to/from_user() error handling IB/hfi1: fix pstateinfo from returning improperly byteswapped value
| * | | | | IB/hfi: Properly set permissions for user device filesIra Weiny2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some of the device files are required to be user accessible for PSM while most should remain accessible only by root. Add a parameter to hfi1_cdev_init which controls if the user should have access to this device which places it in a different class with the appropriate devnode callback. In addition set the devnode call back for the existing class to be a bit more explicit for those permissions. Finally remove the unnecessary null check before class_destroy Tested-by: Donald Dutile <ddutile@redhat.com> Signed-off-by: Haralanov, Mitko (mitko.haralanov@intel.com) Signed-off-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: mask vs shift confusionDan Carpenter2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We are shifting by the _MASK macros instead of the _SHIFT ones. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: clean up some definesDan Carpenter2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I added spaces around operators so it matches kernel style because normally "-1ULL" is a number and " - 1" is a subtract operation. Also removed some superflous "ULL" types so "1ULL" becomes "1". Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: info leak in get_ctxt_info()Dan Carpenter2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The cinfo struct has a hole after the last struct member so we need to zero it out. Otherwise we disclose some uninitialized stack data. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: fix a locking bugDan Carpenter2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mutex_trylock() returns zero on failure, not EBUSY. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: checking for NULL instead of IS_ERRDan Carpenter2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __get_txreq() returns an ERR_PTR() but this checks for NULL so it would oops on failure. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: fix sdma_descq_cnt parameter parsingMike Marciniszyn2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The boolean tests should have been or-ed. Reported-by: David Binderman <dcb314@hotmail.com> Reviewed-by: Jubin John <jubin.john@intel.com> Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: fix copy_to/from_user() error handlingDan Carpenter2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | copy_to/from_user() returns the number of bytes which we were not able to copy. It doesn't return an error code. Also a couple places had a printk() on error and I removed that because people can take advantage of it to fill /var/log/messages with spam. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
| * | | | | IB/hfi1: fix pstateinfo from returning improperly byteswapped valueIra Weiny2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Byteswap link_width_downgrade_*_active values before sending on the wire. In addition properly define the Port State Info structure. Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Reviewed-by: Christian Gomez <christian.gomez@intel.com> Signed-off-by: Rimmer, Todd <todd.rimmer@intel.com> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
* | | | | | Merge branch 'libnvdimm-fixes' of ↵Linus Torvalds2015-09-19
|\ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull libnvdimm fixes from Dan Williams: - a boot regression (since v4.2) fix for some ARM configurations from Tyler - regression (since v4.1) fixes for mkfs.xfs on a DAX enabled device from Jeff. These are tagged for -stable. - a pair of locking fixes from Axel that are hidden from lockdep since they involve device_lock(). The "btt" one is tagged for -stable, the other only applies to the new "pfn" mechanism in v4.3. - a fix for the pmem ->rw_page() path to use wmb_pmem() from Ross. * 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: mm: fix type cast in __pfn_to_phys() pmem: add proper fencing to pmem_rw_page() libnvdimm: pfn_devs: Fix locking in namespace_store libnvdimm: btt_devs: Fix locking in namespace_store blockdev: don't set S_DAX for misaligned partitions dax: fix O_DIRECT I/O to the last block of a blockdev
| * | | | | | mm: fix type cast in __pfn_to_phys()Tyler Baker2015-09-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The various definitions of __pfn_to_phys() have been consolidated to use a generic macro in include/asm-generic/memory_model.h. This hit mainline in the form of 012dcef3f058 "mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h". When the generic macro was implemented the type cast to phys_addr_t was dropped which caused boot regressions on ARM platforms with more than 4GB of memory and LPAE enabled. It was suggested to use PFN_PHYS() defined in include/linux/pfn.h as provides the correct logic and avoids further duplication. Reported-by: kernelci.org bot <bot@kernelci.org> Suggested-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Tyler Baker <tyler.baker@linaro.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * | | | | | pmem: add proper fencing to pmem_rw_page()Ross Zwisler2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | pmem_rw_page() needs to call wmb_pmem() on writes to make sure that the newly written data is durable. This flow was added to pmem_rw_bytes() and pmem_make_request() with this commit: commit 61031952f4c8 ("arch, x86: pmem api for ensuring durability of persistent memory updates") ...the pmem_rw_page() path was missed. Cc: <stable@vger.kernel.org> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * | | | | | libnvdimm: pfn_devs: Fix locking in namespace_storeAxel Lin2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Always take device_lock() before nvdimm_bus_lock() to prevent deadlock. Signed-off-by: Axel Lin <axel.lin@ingics.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * | | | | | libnvdimm: btt_devs: Fix locking in namespace_storeAxel Lin2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Always take device_lock() before nvdimm_bus_lock() to prevent deadlock. Cc: <stable@vger.kernel.org> Signed-off-by: Axel Lin <axel.lin@ingics.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * | | | | | blockdev: don't set S_DAX for misaligned partitionsJeff Moyer2015-09-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The dax code doesn't currently support misaligned partitions, so disable O_DIRECT via dax until such time as that support materializes. Cc: <stable@vger.kernel.org> Suggested-by: Boaz Harrosh <boaz@plexistor.com> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| * | | | | | dax: fix O_DIRECT I/O to the last block of a blockdevJeff Moyer2015-09-15
| | |/ / / / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit bbab37ddc20b (block: Add support for DAX reads/writes to block devices) caused a regression in mkfs.xfs. That utility sets the block size of the device to the logical block size using the BLKBSZSET ioctl, and then issues a single sector read from the last sector of the device. This results in the dax_io code trying to do a page-sized read from 512 bytes from the end of the device. The result is -ERANGE being returned to userspace. The fix is to align the block to the page size before calling get_block. Thanks to willy for simplifying my original patch. Cc: <stable@vger.kernel.org> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Tested-by: Linda Knippers <linda.knippers@hp.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* | | | | | Merge branch 'for-linus' of git://git.kernel.dk/linux-blockLinus Torvalds2015-09-19
|\ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull block updates from Jens Axboe: "This is a bit bigger than it should be, but I could (did) not want to send it off last week due to both wanting extra testing, and expecting a fix for the bounce regression as well. In any case, this contains: - Fix for the blk-merge.c compilation warning on gcc 5.x from me. - A set of back/front SG gap merge fixes, from me and from Sagi. This ensures that we honor SG gapping for integrity payloads as well. - Two small fixes for null_blk from Matias, fixing a leak and a capacity propagation issue. - A blkcg fix from Tejun, fixing a NULL dereference. - A fast clone optimization from Ming, fixing a performance regression since the arbitrarily sized bio's were introduced. - Also from Ming, a regression fix for bouncing IOs" * 'for-linus' of git://git.kernel.dk/linux-block: block: fix bounce_end_io block: blk-merge: fast-clone bio when splitting rw bios block: blkg_destroy_all() should clear q->root_blkg and ->root_rl.blkg block: Copy a user iovec if it includes gaps block: Refuse adding appending a gapped integrity page to a bio block: Refuse request/bio merges with gaps in the integrity payload block: Check for gaps on front and back merges null_blk: fix wrong capacity when bs is not 512 bytes null_blk: fix memory leak on cleanup block: fix bogus compiler warnings in blk-merge.c
| * | | | | | block: fix bounce_end_ioMing Lei2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When bio bounce is involved, one new bio and its biovecs are cloned from the comming bio, which can be one fast-cloned bio from upper layer(such as dm). So it is obviously wrong to assume the start index of the coming( original) bio's io vector is zero, which can be any value between 0 and (bi_max_vecs - 1), especially in case of bio split. This patch fixes Fedora's booting oops on i386, often with the following kernel log together: > [ 9.026738] systemd[1]: Switching root. > [ 9.036467] systemd-journald[149]: Received SIGTERM from PID 1 > (systemd). > [ 9.082262] BUG: Bad page state in process kworker/u5:1 pfn:372ac > [ 9.083989] page:f3d32ae0 count:0 mapcount:0 mapping:f2252178 > index:0x16a > [ 9.085755] flags: 0x40020021(locked|lru|mappedtodisk) > [ 9.087284] page dumped because: page still charged to cgroup > [ 9.088772] bad because of flags: > [ 9.089731] flags: 0x21(locked|lru) > [ 9.090818] page->mem_cgroup:f2c3e400 Reported-by: Josh Boyer <jwboyer@fedoraproject.org> Tested-by: Adam Williamson <awilliam@redhat.com> Cc: Ming Lin <mlin@kernel.org> Cc: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | block: blk-merge: fast-clone bio when splitting rw biosMing Lei2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | biovecs has become immutable since v3.13, so it isn't necessary to allocate biovecs for the new cloned bios, then we can save one extra biovecs allocation/copy, and the allocation is often not fixed-length and a bit more expensive. For example, if the 'max_sectors_kb' of null blk's queue is set as 16(32 sectors) via sysfs just for making more splits, this patch can increase throught about ~70% in the sequential read test over null_blk(direct io, bs: 1M). Cc: Christoph Hellwig <hch@infradead.org> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Ming Lin <ming.l@ssi.samsung.com> Cc: Dongsu Park <dpark@posteo.net> Signed-off-by: Ming Lei <ming.lei@canonical.com> This fixes a performance regression introduced by commit 54efd50bfd, and allows us to take full advantage of the fact that we have immutable bio_vecs. Hand applied, as it rejected violently with commit 5014c311baa2. Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | block: blkg_destroy_all() should clear q->root_blkg and ->root_rl.blkgTejun Heo2015-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While making the root blkg unconditional, ec13b1d6f0a0 ("blkcg: always create the blkcg_gq for the root blkcg") removed the part which clears q->root_blkg and ->root_rl.blkg during q exit. This leaves the two pointers dangling after blkg_destroy_all(). blk-throttle exit path performs blkg traversals and dereferences ->root_blkg and can lead to the following oops. BUG: unable to handle kernel NULL pointer dereference at 0000000000000558 IP: [<ffffffff81389746>] __blkg_lookup+0x26/0x70 ... task: ffff88001b4e2580 ti: ffff88001ac0c000 task.ti: ffff88001ac0c000 RIP: 0010:[<ffffffff81389746>] [<ffffffff81389746>] __blkg_lookup+0x26/0x70 ... Call Trace: [<ffffffff8138d14a>] blk_throtl_drain+0x5a/0x110 [<ffffffff8138a108>] blkcg_drain_queue+0x18/0x20 [<ffffffff81369a70>] __blk_drain_queue+0xc0/0x170 [<ffffffff8136a101>] blk_queue_bypass_start+0x61/0x80 [<ffffffff81388c59>] blkcg_deactivate_policy+0x39/0x100 [<ffffffff8138d328>] blk_throtl_exit+0x38/0x50 [<ffffffff8138a14e>] blkcg_exit_queue+0x3e/0x50 [<ffffffff8137016e>] blk_release_queue+0x1e/0xc0 ... While the bug is a straigh-forward use-after-free bug, it is tricky to reproduce because blkg release is RCU protected and the rest of exit path usually finishes before RCU grace period. This patch fixes the bug by updating blkg_destro_all() to clear q->root_blkg and ->root_rl.blkg. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: "Richard W.M. Jones" <rjones@redhat.com> Reported-by: Josh Boyer <jwboyer@fedoraproject.org> Link: http://lkml.kernel.org/g/CA+5PVA5rzQ0s4723n5rHBcxQa9t0cW8BPPBekr_9aMRoWt2aYg@mail.gmail.com Fixes: ec13b1d6f0a0 ("blkcg: always create the blkcg_gq for the root blkcg") Cc: stable@vger.kernel.org # v4.2+ Tested-by: Richard W.M. Jones <rjones@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | block: Copy a user iovec if it includes gapsSagi Grimberg2015-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For drivers that don't support gaps in the SG lists handed to them we must bounce (copy the user buffers) and pass a bio that does not include gaps. This doesn't matter for any current user, but will help to allow iser which can't handle gaps to use the block virtual boundary instead of using driver-local bounce buffering when handling SG_IO commands. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | block: Refuse adding appending a gapped integrity page to a bioSagi Grimberg2015-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is only theoretical at the moment given that the only subsystems that generate integrity payloads are the block layer itself and the scsi target (which generate well aligned integrity payloads). But when we will expose integrity meta-data to user-space, we'll need to refuse appending a page with a gap (if the queue virtual boundary is set). Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | block: Refuse request/bio merges with gaps in the integrity payloadSagi Grimberg2015-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a driver sets the block queue virtual boundary mask, it means that it cannot handle gaps so we must not allow those in the integrity payload as well. Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Fixed up by me to have duplicate integrity merge functions, depending on whether block integrity is enabled or not. Fixes a compilations issue with CONFIG_BLK_DEV_INTEGRITY unset. Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | block: Check for gaps on front and back mergesJens Axboe2015-09-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We are checking for gaps to previous bio_vec, which can only detect back merges gaps. Moreover, at the point where we check for a gap, we don't know if we will attempt a back or a front merge. Thus, check for gap to prev in a back merge attempt and check for a gap to next in a front merge attempt. Signed-off-by: Jens Axboe <axboe@fb.com> [sagig: Minor rename change] Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
| * | | | | | null_blk: fix wrong capacity when bs is not 512 bytesMatias Bjørling2015-09-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | set_capacity() sets device's capacity using 512 bytes sectors. null_blk calculates the number of sectors by size / bs, which set_capacity is called with. This led to null_blk exposing the wrong number of sectors when bs is not 512 bytes. Signed-off-by: Matias Bjørling <m@bjorling.me> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | null_blk: fix memory leak on cleanupMatias Bjørling2015-09-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Driver was not freeing the memory allocated for internal nullb queues. This patch frees the memory during driver unload. Signed-off-by: Matias Bjørling <mb@lightnvm.io> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | | | | block: fix bogus compiler warnings in blk-merge.cJens Axboe2015-09-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The compiler can't figure out that bvprv is initialized whenever 'prev' is set to 1 as well. Use a pointer to bvprv instead, setting it to NULL initially, and get rid of the 'prev' tracking. This dumbs it down enough that gcc is happy. Signed-off-by: Jens Axboe <axboe@fb.com>
* | | | | | | fs-writeback: unplug before cond_resched in writeback_sb_inodesChris Mason2015-09-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 505a666ee3fc ("writeback: plug writeback in wb_writeback() and writeback_inodes_wb()") has us holding a plug during writeback_sb_inodes, which increases the merge rate when relatively contiguous small files are written by the filesystem. It helps both on flash and spindles. For an fs_mark workload creating 4K files in parallel across 8 drives, this commit improves performance ~9% more by unplugging before calling cond_resched(). cond_resched() doesn't trigger an implicit unplug, so explicitly getting the IO down to the device before scheduling reduces latencies for anyone waiting on clean pages. It also cuts down on how often we use kblockd to unplug, which means less work bouncing from one workqueue to another. Many more details about how we got here: https://lkml.org/lkml/2015/9/11/570 Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | | | | | Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhostLinus Torvalds2015-09-18
|\ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull virtio fixes and cleanups from Michael Tsirkin: "This fixes the virtio-test tool, and improves the error handling for virtio-ccw" * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: virtio/s390: handle failures of READ_VQ_CONF ccw tools/virtio: propagate V=X to kernel build vhost: move features to core tools/virtio: fix build after 4.2 changes
| * | | | | | | virtio/s390: handle failures of READ_VQ_CONF ccwPierre Morel2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In virtio_ccw_read_vq_conf() the return value of ccw_io_helper() was not checked. If the configuration could not be read properly, we'd wrongly assume a queue size of 0. Let's propagate any I/O error to virtio_ccw_setup_vq() so it may properly fail. Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
| * | | | | | | tools/virtio: propagate V=X to kernel buildMichael S. Tsirkin2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
| * | | | | | | vhost: move features to coreMichael S. Tsirkin2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | virtio 1 and any layout are core features, move them there. This fixes vhost test. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
| * | | | | | | tools/virtio: fix build after 4.2 changesMichael S. Tsirkin2015-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | more stubs, mostly Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* | | | | | | | Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds2015-09-18
|\ \ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull KVM fixes from Paolo Bonzini: "Mostly stable material, a lot of ARM fixes" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (22 commits) sched: access local runqueue directly in single_task_running arm/arm64: KVM: Remove 'config KVM_ARM_MAX_VCPUS' arm64: KVM: Remove all traces of the ThumbEE registers arm: KVM: Disable virtual timer even if the guest is not using it arm64: KVM: Disable virtual timer even if the guest is not using it arm/arm64: KVM: vgic: Check for !irqchip_in_kernel() when mapping resources KVM: s390: Replace incorrect atomic_or with atomic_andnot arm: KVM: Fix incorrect device to IPA mapping arm64: KVM: Fix user access for debug registers KVM: vmx: fix VPID is 0000H in non-root operation KVM: add halt_attempted_poll to VCPU stats kvm: fix zero length mmio searching kvm: fix double free for fast mmio eventfd kvm: factor out core eventfd assign/deassign logic kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd KVM: make the declaration of functions within 80 characters KVM: arm64: add workaround for Cortex-A57 erratum #852523 KVM: fix polling for guest halt continued even if disable it arm/arm64: KVM: Fix PSCI affinity info return value for non valid cores arm64: KVM: set {v,}TCR_EL2 RES1 bits ...
| * | | | | | | | sched: access local runqueue directly in single_task_runningDominik Dingel2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 2ee507c47293 ("sched: Add function single_task_running to let a task check if it is the only task running on a cpu") referenced the current runqueue with the smp_processor_id. When CONFIG_DEBUG_PREEMPT is enabled, that is only allowed if preemption is disabled or the currrent task is bound to the local cpu (e.g. kernel worker). With commit f78195129963 ("kvm: add halt_poll_ns module parameter") KVM calls single_task_running. If CONFIG_DEBUG_PREEMPT is enabled that generates a lot of kernel messages. To avoid adding preemption in that cases, as it would limit the usefulness, we change single_task_running to access directly the cpu local runqueue. Cc: Tim Chen <tim.c.chen@linux.intel.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> Fixes: 2ee507c472939db4b146d545352b8a7c79ef47f8 Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| * | | | | | | | Merge tag 'kvm-arm-for-4.3-rc2-2' of ↵Paolo Bonzini2015-09-17
| |\ \ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master Second set of KVM/ARM changes for 4.3-rc2 - Workaround for a Cortex-A57 erratum - Bug fix for the debugging infrastructure - Fix for 32bit guests with more than 4GB of address space on a 32bit host - A number of fixes for the (unusual) case when we don't use the in-kernel GIC emulation - Removal of ThumbEE handling on arm64, since these have been dropped from the architecture before anyone actually ever built a CPU - Remove the KVM_ARM_MAX_VCPUS limitation which has become fairly pointless
| | * | | | | | | | arm/arm64: KVM: Remove 'config KVM_ARM_MAX_VCPUS'Ming Lei2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch removes config option of KVM_ARM_MAX_VCPUS, and like other ARCHs, just choose the maximum allowed value from hardware, and follows the reasons: 1) from distribution view, the option has to be defined as the max allowed value because it need to meet all kinds of virtulization applications and need to support most of SoCs; 2) using a bigger value doesn't introduce extra memory consumption, and the help text in Kconfig isn't accurate because kvm_vpu structure isn't allocated until request of creating VCPU is sent from QEMU; 3) the main effect is that the field of vcpus[] in 'struct kvm' becomes a bit bigger(sizeof(void *) per vcpu) and need more cache lines to hold the structure, but 'struct kvm' is one generic struct, and it has worked well on other ARCHs already in this way. Also, the world switch frequecy is often low, for example, it is ~2000 when running kernel building load in VM from APM xgene KVM host, so the effect is very small, and the difference can't be observed in my test at all. Cc: Dann Frazier <dann.frazier@canonical.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| | * | | | | | | | arm64: KVM: Remove all traces of the ThumbEE registersWill Deacon2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Although the ThumbEE registers and traps were present in earlier versions of the v8 architecture, it was retrospectively removed and so we can do the same. Whilst this breaks migrating a guest started on a previous version of the kernel, it is much better to kill these (non existent) registers as soon as possible. Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> [maz: added commend about migration] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| | * | | | | | | | arm: KVM: Disable virtual timer even if the guest is not using itMarc Zyngier2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When running a guest with the architected timer disabled (with QEMU and the kernel_irqchip=off option, for example), it is important to make sure the timer gets turned off. Otherwise, the guest may try to enable it anyway, leading to a screaming HW interrupt. The fix is to unconditionally turn off the virtual timer on guest exit. Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| | * | | | | | | | arm64: KVM: Disable virtual timer even if the guest is not using itMarc Zyngier2015-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When running a guest with the architected timer disabled (with QEMU and the kernel_irqchip=off option, for example), it is important to make sure the timer gets turned off. Otherwise, the guest may try to enable it anyway, leading to a screaming HW interrupt. The fix is to unconditionally turn off the virtual timer on guest exit. Cc: stable@vger.kernel.org Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| | * | | | | | | | arm/arm64: KVM: vgic: Check for !irqchip_in_kernel() when mapping resourcesPavel Fedin2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Until b26e5fdac43c ("arm/arm64: KVM: introduce per-VM ops"), kvm_vgic_map_resources() used to include a check on irqchip_in_kernel(), and vgic_v2_map_resources() still has it. But now vm_ops are not initialized until we call kvm_vgic_create(). Therefore kvm_vgic_map_resources() can being called without a VGIC, and we die because vm_ops.map_resources is NULL. Fixing this restores QEMU's kernel-irqchip=off option to a working state, allowing to use GIC emulation in userspace. Fixes: b26e5fdac43c ("arm/arm64: KVM: introduce per-VM ops") Cc: stable@vger.kernel.org Signed-off-by: Pavel Fedin <p.fedin@samsung.com> [maz: reworked commit message] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| | * | | | | | | | arm: KVM: Fix incorrect device to IPA mappingMarek Majtyka2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A critical bug has been found in device memory stage1 translation for VMs with more then 4GB of address space. Once vm_pgoff size is smaller then pa (which is true for LPAE case, u32 and u64 respectively) some more significant bits of pa may be lost as a shift operation is performed on u32 and later cast onto u64. Example: vm_pgoff(u32)=0x00210030, PAGE_SHIFT=12 expected pa(u64): 0x0000002010030000 produced pa(u64): 0x0000000010030000 The fix is to change the order of operations (casting first onto phys_addr_t and then shifting). Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> [maz: fixed changelog and patch formatting] Cc: stable@vger.kernel.org Signed-off-by: Marek Majtyka <marek.majtyka@tieto.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| | * | | | | | | | arm64: KVM: Fix user access for debug registersMarc Zyngier2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When setting the debug register from userspace, make sure that copy_from_user() is called with its parameters in the expected order. It otherwise doesn't do what you think. Fixes: 84e690bfbed1 ("KVM: arm64: introduce vcpu->arch.debug_ptr") Reported-by: Peter Maydell <peter.maydell@linaro.org> Cc: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| | * | | | | | | | KVM: arm64: add workaround for Cortex-A57 erratum #852523Will Deacon2015-09-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When restoring the system register state for an AArch32 guest at EL2, writes to DACR32_EL2 may not be correctly synchronised by Cortex-A57, which can lead to the guest effectively running with junk in the DACR and running into unexpected domain faults. This patch works around the issue by re-ordering our restoration of the AArch32 register aliases so that they happen before the AArch64 system registers. Ensuring that the registers are restored in this order guarantees that they will be correctly synchronised by the core. Cc: <stable@vger.kernel.org> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
| * | | | | | | | | KVM: s390: Replace incorrect atomic_or with atomic_andnotJason J. Herne2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The offending commit accidentally replaces an atomic_clear with an atomic_or instead of an atomic_andnot in kvm_s390_vcpu_request_handled. The symptom is that kvm guests on s390 hang on startup. This patch simply replaces the incorrect atomic_or with atomic_andnot Fixes: 805de8f43c20 (atomic: Replace atomic_{set,clear}_mask() usage) Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| * | | | | | | | | KVM: vmx: fix VPID is 0000H in non-root operationWanpeng Li2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Reference SDM 28.1: The current VPID is 0000H in the following situations: - Outside VMX operation. (This includes operation in system-management mode under the default treatment of SMIs and SMM with VMX operation; see Section 34.14.) - In VMX root operation. - In VMX non-root operation when the “enable VPID” VM-execution control is 0. The VPID should never be 0000H in non-root operation when "enable VPID" VM-execution control is 1. However, commit 34a1cd60 ("kvm: x86: vmx: move some vmx setting from vmx_init() to hardware_setup()") remove the codes which reserve 0000H for VMX root operation. This patch fix it by again reserving 0000H for VMX root operation. Cc: stable@vger.kernel.org # 3.19+ Fixes: 34a1cd60d17f62c1f077c1478a6c2ca8c3d17af4 Reported-by: Wincy Van <fanwenyi0529@gmail.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| * | | | | | | | | KVM: add halt_attempted_poll to VCPU statsPaolo Bonzini2015-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This new statistic can help diagnosing VCPUs that, for any reason, trigger bad behavior of halt_poll_ns autotuning. For example, say halt_poll_ns = 480000, and wakeups are spaced exactly like 479us, 481us, 479us, 481us. Then KVM always fails polling and wastes 10+20+40+80+160+320+480 = 1110 microseconds out of every 479+481+479+481+479+481+479 = 3359 microseconds. The VCPU then is consuming about 30% more CPU than it would use without polling. This would show as an abnormally high number of attempted polling compared to the successful polls. Acked-by: Christian Borntraeger <borntraeger@de.ibm.com< Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| * | | | | | | | | kvm: fix zero length mmio searchingJason Wang2015-09-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, if we had a zero length mmio eventfd assigned on KVM_MMIO_BUS. It will never be found by kvm_io_bus_cmp() since it always compares the kvm_io_range() with the length that guest wrote. This will cause e.g for vhost, kick will be trapped by qemu userspace instead of vhost. Fixing this by using zero length if an iodevice is zero length. Cc: stable@vger.kernel.org Cc: Gleb Natapov <gleb@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>