linux-stable.git/drivers/xen, branch v4.12.2

xen: avoid deadlock in xenbus driver

2017-07-12T14:55:26+00:00

commit 1a3fc2c402810bf336882e695abd1678dbc8d279 upstream.

There has been a report about a deadlock in the xenbus driver:

[  247.979498] ======================================================
[  247.985688] WARNING: possible circular locking dependency detected
[  247.991882] 4.12.0-rc4-00022-gc4b25c0 #575 Not tainted
[  247.997040] ------------------------------------------------------
[  248.003232] xenbus/91 is trying to acquire lock:
[  248.007875]  (&u->msgbuffer_mutex){+.+.+.}, at: []
xenbus_dev_queue_reply+0x3c/0x230
[  248.017163]
[  248.017163] but task is already holding lock:
[  248.023096]  (xb_write_mutex){+.+...}, at: []
xenbus_thread+0x5f0/0x798
[  248.031267]
[  248.031267] which lock already depends on the new lock.
[  248.031267]
[  248.039615]
[  248.039615] the existing dependency chain (in reverse order) is:
[  248.047176]
[  248.047176] -> #1 (xb_write_mutex){+.+...}:
[  248.052943]        __lock_acquire+0x1728/0x1778
[  248.057498]        lock_acquire+0xc4/0x288
[  248.061630]        __mutex_lock+0x84/0x868
[  248.065755]        mutex_lock_nested+0x3c/0x50
[  248.070227]        xs_send+0x164/0x1f8
[  248.074015]        xenbus_dev_request_and_reply+0x6c/0x88
[  248.079427]        xenbus_file_write+0x260/0x420
[  248.084073]        __vfs_write+0x48/0x138
[  248.088113]        vfs_write+0xa8/0x1b8
[  248.091983]        SyS_write+0x54/0xb0
[  248.095768]        el0_svc_naked+0x24/0x28
[  248.099897]
[  248.099897] -> #0 (&u->msgbuffer_mutex){+.+.+.}:
[  248.106088]        print_circular_bug+0x80/0x2e0
[  248.110730]        __lock_acquire+0x1768/0x1778
[  248.115288]        lock_acquire+0xc4/0x288
[  248.119417]        __mutex_lock+0x84/0x868
[  248.123545]        mutex_lock_nested+0x3c/0x50
[  248.128016]        xenbus_dev_queue_reply+0x3c/0x230
[  248.133005]        xenbus_thread+0x788/0x798
[  248.137306]        kthread+0x110/0x140
[  248.141087]        ret_from_fork+0x10/0x40

It is rather easy to avoid by dropping xb_write_mutex before calling
xenbus_dev_queue_reply().

Fixes: fd8aa9095a95c02dcc35540a263267c29b8fda9d ("xen: optimize xenbus
driver for multiple concurrent xenstore accesses").

Reported-by: Andre Przywara 
Signed-off-by: Juergen Gross 
Tested-by: Andre Przywara 
Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'for-linus-4.12b-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2017-06-09T16:59:51+00:00

Pull xen fix from Juergen Gross:
 "A fix for Xen on ARM when dealing with 64kB page size of a guest"

* tag 'for-linus-4.12b-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/privcmd: Support correctly 64KB page granularity when mapping memory

xen/privcmd: Support correctly 64KB page granularity when mapping memory

2017-06-07T09:23:14+00:00

Commit 5995a68 "xen/privcmd: Add support for Linux 64KB page granularity" did
not go far enough to support 64KB in mmap_batch_fn.

The variable 'nr' is the number of 4KB chunk to map. However, when Linux
is using 64KB page granularity the array of pages (vma->vm_private_data)
contain one page per 64KB. Fix it by incrementing st->index correctly.

Furthermore, st->va is not correctly incremented as PAGE_SIZE !=
XEN_PAGE_SIZE.

Fixes: 5995a68 ("xen/privcmd: Add support for Linux 64KB page granularity")
CC: stable@vger.kernel.org
Reported-by: Feng Kan 
Signed-off-by: Julien Grall 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross

Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2017-05-09T16:12:53+00:00

Pull misc vfs updates from Al Viro:
 "Assorted bits and pieces from various people. No common topic in this
  pile, sorry"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs/affs: add rename exchange
  fs/affs: add rename2 to prepare multiple methods
  Make stat/lstat/fstatat pass AT_NO_AUTOMOUNT to vfs_statx()
  fs: don't set *REFERENCED on single use objects
  fs: compat: Remove warning from COMPATIBLE_IOCTL
  remove pointless extern of atime_need_update_rcu()
  fs: completely ignore unknown open flags
  fs: add a VALID_OPEN_FLAGS
  fs: remove _submit_bh()
  fs: constify tree_descr arrays passed to simple_fill_super()
  fs: drop duplicate header percpu-rwsem.h
  fs/affs: bugfix: Write files greater than page size on OFS
  fs/affs: bugfix: enable writes on OFS disks
  fs/affs: remove node generation check
  fs/affs: import amigaffs.h
  fs/affs: bugfix: make symbolic links work again

treewide: use kv[mz]alloc* rather than opencoded variants

2017-05-09T00:15:13+00:00

There are many code paths opencoding kvmalloc.  Let's use the helper
instead.  The main difference to kvmalloc is that those users are
usually not considering all the aspects of the memory allocator.  E.g.
allocation requests <= 32kB (with 4kB pages) are basically never failing
and invoke OOM killer to satisfy the allocation.  This sounds too
disruptive for something that has a reasonable fallback - the vmalloc.
On the other hand those requests might fallback to vmalloc even when the
memory allocator would succeed after several more reclaim/compaction
attempts previously.  There is no guarantee something like that happens
though.

This patch converts many of those places to kv[mz]alloc* helpers because
they are more conservative.

Link: http://lkml.kernel.org/r/20170306103327.2766-2-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Reviewed-by: Boris Ostrovsky  # Xen bits
Acked-by: Kees Cook 
Acked-by: Vlastimil Babka 
Acked-by: Andreas Dilger  # Lustre
Acked-by: Christian Borntraeger  # KVM/s390
Acked-by: Dan Williams  # nvdim
Acked-by: David Sterba  # btrfs
Acked-by: Ilya Dryomov  # Ceph
Acked-by: Tariq Toukan  # mlx4
Acked-by: Leon Romanovsky  # mlx5
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Herbert Xu 
Cc: Anton Vorontsov 
Cc: Colin Cross 
Cc: Tony Luck 
Cc: "Rafael J. Wysocki" 
Cc: Ben Skeggs 
Cc: Kent Overstreet 
Cc: Santosh Raspatur 
Cc: Hariprasad S 
Cc: Yishai Hadas 
Cc: Oleg Drokin 
Cc: "Yan, Zheng" 
Cc: Alexander Viro 
Cc: Alexei Starovoitov 
Cc: Eric Dumazet 
Cc: David Miller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

xen: Implement EFI reset_system callback

2017-05-02T10:06:50+00:00

When rebooting DOM0 with ACPI on ARM64, the kernel is crashing with the stack
trace [1].

This is happening because when EFI runtimes are enabled, the reset code
(see machine_restart) will first try to use EFI restart method.

However, the EFI restart code is expecting the reset_system callback to
be always set. This is not the case for Xen and will lead to crash.

The EFI restart helper is used in multiple places and some of them don't
not have fallback (see machine_power_off). So implement reset_system
callback as a call to xen_reboot when using EFI Xen.

[   36.999270] reboot: Restarting system
[   37.002921] Internal error: Attempting to execute userspace memory: 86000004 [#1] PREEMPT SMP
[   37.011460] Modules linked in:
[   37.014598] CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 4.11.0-rc1-00003-g1e248b60a39b-dirty #506
[   37.023903] Hardware name: (null) (DT)
[   37.027734] task: ffff800902068000 task.stack: ffff800902064000
[   37.033739] PC is at 0x0
[   37.036359] LR is at efi_reboot+0x94/0xd0
[   37.040438] pc : [<0000000000000000>] lr : [] pstate: 404001c5
[   37.047920] sp : ffff800902067cf0
[   37.051314] x29: ffff800902067cf0 x28: ffff800902068000
[   37.056709] x27: ffff000008992000 x26: 000000000000008e
[   37.062104] x25: 0000000000000123 x24: 0000000000000015
[   37.067499] x23: 0000000000000000 x22: ffff000008e6e250
[   37.072894] x21: ffff000008e6e000 x20: 0000000000000000
[   37.078289] x19: ffff000008e5d4c8 x18: 0000000000000010
[   37.083684] x17: 0000ffffa7c27470 x16: 00000000deadbeef
[   37.089079] x15: 0000000000000006 x14: ffff000088f42bef
[   37.094474] x13: ffff000008f42bfd x12: ffff000008e706c0
[   37.099870] x11: ffff000008e70000 x10: 0000000005f5e0ff
[   37.105265] x9 : ffff800902067a50 x8 : 6974726174736552
[   37.110660] x7 : ffff000008cc6fb8 x6 : ffff000008cc6fb0
[   37.116055] x5 : ffff000008c97dd8 x4 : 0000000000000000
[   37.121453] x3 : 0000000000000000 x2 : 0000000000000000
[   37.126845] x1 : 0000000000000000 x0 : 0000000000000000
[   37.132239]
[   37.133808] Process systemd-shutdow (pid: 1, stack limit = 0xffff800902064000)
[   37.141118] Stack: (0xffff800902067cf0 to 0xffff800902068000)
[   37.146949] 7ce0:                                   ffff800902067d40 ffff000008085334
[   37.154869] 7d00: 0000000000000000 ffff000008f3b000 ffff800902067d40 ffff0000080852e0
[   37.162787] 7d20: ffff000008cc6fb0 ffff000008cc6fb8 ffff000008c7f580 ffff000008c97dd8
[   37.170706] 7d40: ffff800902067d60 ffff0000080e2c2c 0000000000000000 0000000001234567
[   37.178624] 7d60: ffff800902067d80 ffff0000080e2ee8 0000000000000000 ffff0000080e2df4
[   37.186544] 7d80: 0000000000000000 ffff0000080830f0 0000000000000000 00008008ff1c1000
[   37.194462] 7da0: ffffffffffffffff 0000ffffa7c4b1cc 0000000000000000 0000000000000024
[   37.202380] 7dc0: ffff800902067dd0 0000000000000005 0000fffff24743c8 0000000000000004
[   37.210299] 7de0: 0000fffff2475f03 0000000000000010 0000fffff2474418 0000000000000005
[   37.218218] 7e00: 0000fffff2474578 000000000000000a 0000aaaad6b722c0 0000000000000001
[   37.226136] 7e20: 0000000000000123 0000000000000038 ffff800902067e50 ffff0000081e7294
[   37.234055] 7e40: ffff800902067e60 ffff0000081e935c ffff800902067e60 ffff0000081e9388
[   37.241973] 7e60: ffff800902067eb0 ffff0000081ea388 0000000000000000 00008008ff1c1000
[   37.249892] 7e80: ffffffffffffffff 0000ffffa7c4a79c 0000000000000000 ffff000000020000
[   37.257810] 7ea0: 0000010000000004 0000000000000000 0000000000000000 ffff0000080830f0
[   37.265729] 7ec0: fffffffffee1dead 0000000028121969 0000000001234567 0000000000000000
[   37.273651] 7ee0: ffffffffffffffff 8080000000800000 0000800000008080 feffa9a9d4ff2d66
[   37.281567] 7f00: 000000000000008e feffa9a9d5b60e0f 7f7fffffffff7f7f 0101010101010101
[   37.289485] 7f20: 0000000000000010 0000000000000008 000000000000003a 0000ffffa7ccf588
[   37.297404] 7f40: 0000aaaad6b87d00 0000ffffa7c4b1b0 0000fffff2474be0 0000aaaad6b88000
[   37.305326] 7f60: 0000fffff2474fb0 0000000001234567 0000000000000000 0000000000000000
[   37.313240] 7f80: 0000000000000000 0000000000000001 0000aaaad6b70d4d 0000000000000000
[   37.321159] 7fa0: 0000000000000001 0000fffff2474ea0 0000aaaad6b5e2e0 0000fffff2474e80
[   37.329078] 7fc0: 0000ffffa7c4b1cc 0000000000000000 fffffffffee1dead 000000000000008e
[   37.336997] 7fe0: 0000000000000000 0000000000000000 9ce839cffee77eab fafdbf9f7ed57f2f
[   37.344911] Call trace:
[   37.347437] Exception stack(0xffff800902067b20 to 0xffff800902067c50)
[   37.353970] 7b20: ffff000008e5d4c8 0001000000000000 0000000080f82000 0000000000000000
[   37.361883] 7b40: ffff800902067b60 ffff000008e17000 ffff000008f44c68 00000001081081b4
[   37.369802] 7b60: ffff800902067bf0 ffff000008108478 0000000000000000 ffff000008c235b0
[   37.377721] 7b80: ffff800902067ce0 0000000000000000 0000000000000000 0000000000000015
[   37.385643] 7ba0: 0000000000000123 000000000000008e ffff000008992000 ffff800902068000
[   37.393557] 7bc0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[   37.401477] 7be0: 0000000000000000 ffff000008c97dd8 ffff000008cc6fb0 ffff000008cc6fb8
[   37.409396] 7c00: 6974726174736552 ffff800902067a50 0000000005f5e0ff ffff000008e70000
[   37.417318] 7c20: ffff000008e706c0 ffff000008f42bfd ffff000088f42bef 0000000000000006
[   37.425234] 7c40: 00000000deadbeef 0000ffffa7c27470
[   37.430190] [<          (null)>]           (null)
[   37.434982] [] machine_restart+0x6c/0x70
[   37.440550] [] kernel_restart+0x6c/0x78
[   37.446030] [] SyS_reboot+0x130/0x228
[   37.451337] [] el0_svc_naked+0x24/0x28
[   37.456737] Code: bad PC value
[   37.459891] ---[ end trace 76e2fc17e050aecd ]---

Signed-off-by: Julien Grall 

--

Cc: Boris Ostrovsky 
Cc: Juergen Gross 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: x86@kernel.org

The x86 code has theoritically a similar issue, altought EFI does not
seem to be the preferred method. I have only built test it on x86.

This should also probably be fixed in stable tree.

    Changes in v2:
        - Implement xen_efi_reset_system using xen_reboot
        - Move xen_efi_reset_system in drivers/xen/efi.c
Signed-off-by: Juergen Gross

xen: Revert commits da72ff5bfcb0 and 72a9b186292d

2017-05-02T09:18:05+00:00

Recent discussion (http://marc.info/?l=xen-devel&m=149192184523741)
established that commit 72a9b186292d ("xen: Remove event channel
notification through Xen PCI platform device") (and thus commit
da72ff5bfcb0 ("partially revert "xen: Remove event channel
notification through Xen PCI platform device"")) are unnecessary and,
in fact, prevent HVM guests from booting on Xen releases prior to 4.0

Therefore we revert both of those commits.

The summary of that discussion is below:

  Here is the brief summary of the current situation:

  Before the offending commit (72a9b186292):

  1) INTx does not work because of the reset_watches path.
  2) The reset_watches path is only taken if you have Xen > 4.0
  3) The Linux Kernel by default will use vector inject if the hypervisor
     support. So even INTx does not work no body running the kernel with
     Xen > 4.0 would notice. Unless he explicitly disabled this feature
     either in the kernel or in Xen (and this can only be disabled by
     modifying the code, not user-supported way to do it).

  After the offending commit (+ partial revert):

  1) INTx is no longer support for HVM (only for PV guests).
  2) Any HVM guest The kernel will not boot on Xen < 4.0 which does
     not have vector injection support. Since the only other mode
     supported is INTx which.

  So based on this summary, I think before commit (72a9b186292) we were
  in much better position from a user point of view.

Signed-off-by: Boris Ostrovsky 
Reviewed-by: Juergen Gross 
Signed-off-by: Juergen Gross

xen/arm,arm64: rename __generic_dma_ops to xen_get_dma_ops

2017-05-02T09:14:47+00:00

Now that __generic_dma_ops is a xen specific function, rename it to
xen_get_dma_ops. Change all the call sites appropriately.

Signed-off-by: Stefano Stabellini 
Reviewed-by: Boris Ostrovsky 
Acked-by: Konrad Rzeszutek Wilk 
CC: linux@armlinux.org.uk
CC: catalin.marinas@arm.com
CC: will.deacon@arm.com
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
CC: Julien Grall

xen/balloon: decorate PV-only parts with #ifdef CONFIG_XEN_PV

2017-05-02T09:09:56+00:00

Balloon driver uses several PV-only concepts (xen_start_info,
xen_extra_mem,..) and it seems the simpliest solution to make HVM-only
build happy is to decorate these parts with #ifdefs.

Signed-off-by: Vitaly Kuznetsov 
Reviewed-by: Juergen Gross 
Signed-off-by: Juergen Gross

fs: constify tree_descr arrays passed to simple_fill_super()

2017-04-27T03:54:06+00:00

simple_fill_super() is passed an array of tree_descr structures which
describe the files to create in the filesystem's root directory.  Since
these arrays are never modified intentionally, they should be 'const' so
that they are placed in .rodata and benefit from memory protection.
This patch updates the function signature and all users, and also
constifies tree_descr.name.

Signed-off-by: Eric Biggers 
Signed-off-by: Al Viro