linux-stable.git/drivers/xen, branch linux-4.8.y

xen/gntdev: Use VM_MIXEDMAP instead of VM_IO to avoid NUMA balancing

2017-01-06T10:16:24+00:00

commit 30faaafdfa0c754c91bac60f216c9f34a2bfdf7e upstream.

Commit 9c17d96500f7 ("xen/gntdev: Grant maps should not be subject to
NUMA balancing") set VM_IO flag to prevent grant maps from being
subjected to NUMA balancing.

It was discovered recently that this flag causes get_user_pages() to
always fail with -EFAULT.

check_vma_flags
__get_user_pages
__get_user_pages_locked
__get_user_pages_unlocked
get_user_pages_fast
iov_iter_get_pages
dio_refill_pages
do_direct_IO
do_blockdev_direct_IO
do_blockdev_direct_IO
ext4_direct_IO_read
generic_file_read_iter
aio_run_iocb

(which can happen if guest's vdisk has direct-io-safe option).

To avoid this let's use VM_MIXEDMAP flag instead --- it prevents
NUMA balancing just as VM_IO does and has no effect on
check_vma_flags().


Reported-by: Olaf Hering 
Suggested-by: Hugh Dickins 
Signed-off-by: Boris Ostrovsky 
Acked-by: Hugh Dickins 
Tested-by: Olaf Hering 
Signed-off-by: Juergen Gross 
Signed-off-by: Greg Kroah-Hartman

xenbus: don't look up transaction IDs for ordinary writes

2016-08-24T17:16:18+00:00

This should really only be done for XS_TRANSACTION_END messages, or
else at least some of the xenstore-* tools don't work anymore.

Fixes: 0beef634b8 ("xenbus: don't BUG() on user mode induced condition")
Reported-by: Richard Schütz 
Cc: 
Signed-off-by: Jan Beulich 
Tested-by: Richard Schütz 
Signed-off-by: David Vrabel

dma-mapping: use unsigned long for dma_attrs

2016-08-04T12:50:07+00:00

The dma-mapping core and the implementations do not change the DMA
attributes passed by pointer.  Thus the pointer can point to const data.
However the attributes do not have to be a bitfield.  Instead unsigned
long will do fine:

1. This is just simpler.  Both in terms of reading the code and setting
   attributes.  Instead of initializing local attributes on the stack
   and passing pointer to it to dma_set_attr(), just set the bits.

2. It brings safeness and checking for const correctness because the
   attributes are passed by value.

Semantic patches for this change (at least most of them):

    virtual patch
    virtual context

    @r@
    identifier f, attrs;

    @@
    f(...,
    - struct dma_attrs *attrs
    + unsigned long attrs
    , ...)
    {
    ...
    }

    @@
    identifier r.f;
    @@
    f(...,
    - NULL
    + 0
     )

and

    // Options: --all-includes
    virtual patch
    virtual context

    @r@
    identifier f, attrs;
    type t;

    @@
    t f(..., struct dma_attrs *attrs);

    @@
    identifier r.f;
    @@
    f(...,
    - NULL
    + 0
     )

Link: http://lkml.kernel.org/r/1468399300-5399-2-git-send-email-k.kozlowski@samsung.com
Signed-off-by: Krzysztof Kozlowski 
Acked-by: Vineet Gupta 
Acked-by: Robin Murphy 
Acked-by: Hans-Christian Noren Egtvedt 
Acked-by: Mark Salter  [c6x]
Acked-by: Jesper Nilsson  [cris]
Acked-by: Daniel Vetter  [drm]
Reviewed-by: Bart Van Assche 
Acked-by: Joerg Roedel  [iommu]
Acked-by: Fabien Dessenne  [bdisp]
Reviewed-by: Marek Szyprowski  [vb2-core]
Acked-by: David Vrabel  [xen]
Acked-by: Konrad Rzeszutek Wilk  [xen swiotlb]
Acked-by: Joerg Roedel  [iommu]
Acked-by: Richard Kuo  [hexagon]
Acked-by: Geert Uytterhoeven  [m68k]
Acked-by: Gerald Schaefer  [s390]
Acked-by: Bjorn Andersson 
Acked-by: Hans-Christian Noren Egtvedt  [avr32]
Acked-by: Vineet Gupta  [arc]
Acked-by: Robin Murphy  [arm64 and dma-iommu]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'for-linus-4.8-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2016-07-27T18:35:37+00:00

Pull xen updates from David Vrabel:
 "Features and fixes for 4.8-rc0:

   - ACPI support for guests on ARM platforms.
   - Generic steal time support for arm and x86.
   - Support cases where kernel cpu is not Xen VCPU number (e.g., if
     in-guest kexec is used).
   - Use the system workqueue instead of a custom workqueue in various
     places"

* tag 'for-linus-4.8-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: (47 commits)
  xen: add static initialization of steal_clock op to xen_time_ops
  xen/pvhvm: run xen_vcpu_setup() for the boot CPU
  xen/evtchn: use xen_vcpu_id mapping
  xen/events: fifo: use xen_vcpu_id mapping
  xen/events: use xen_vcpu_id mapping in events_base
  x86/xen: use xen_vcpu_id mapping when pointing vcpu_info to shared_info
  x86/xen: use xen_vcpu_id mapping for HYPERVISOR_vcpu_op
  xen: introduce xen_vcpu_id mapping
  x86/acpi: store ACPI ids from MADT for future usage
  x86/xen: update cpuid.h from Xen-4.7
  xen/evtchn: add IOCTL_EVTCHN_RESTRICT
  xen-blkback: really don't leak mode property
  xen-blkback: constify instance of "struct attribute_group"
  xen-blkfront: prefer xenbus_scanf() over xenbus_gather()
  xen-blkback: prefer xenbus_scanf() over xenbus_gather()
  xen: support runqueue steal time on xen
  arm/xen: add support for vm_assist hypercall
  xen: update xen headers
  xen-pciback: drop superfluous variables
  xen-pciback: short-circuit read path used for merging write values
  ...

mm, frontswap: convert frontswap_enabled to static key

2016-07-26T23:19:19+00:00

I have noticed that frontswap.h first declares "frontswap_enabled" as
extern bool variable, and then overrides it with "#define
frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled.  The
bool variable isn't actually instantiated anywhere.

This all looks like an unfinished attempt to make frontswap_enabled
reflect whether a backend is instantiated.  But in the current state,
all frontswap hooks call unconditionally into frontswap.c just to check
if frontswap_ops is non-NULL.  This should at least be checked inline,
but we can further eliminate the overhead when CONFIG_FRONTSWAP is
enabled and no backend registered, using a static key that is initially
disabled, and gets enabled only upon first backend registration.

Thus, checks for "frontswap_enabled" are replaced with
"frontswap_enabled()" wrapping the static key check.  There are two
exceptions:

- xen's selfballoon_process() was testing frontswap_enabled in code guarded
  by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable.
  The patch just removes this check. Using frontswap_enabled() does not sound
  correct here, as this can be true even without xen's own backend being
  registered.

- in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP)
  as it seems the bitmap allocation cannot currently be postponed until a
  backend is registered. This means that frontswap will still have some
  memory overhead by being configured, but without a backend.

After the patch, we can expect that some functions in frontswap.c are
called only when frontswap_ops is non-NULL.  Change the checks there to
VM_BUG_ONs.  While at it, convert other BUG_ONs to VM_BUG_ONs as
frontswap has been stable for some time.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz
Signed-off-by: Vlastimil Babka 
Cc: Konrad Rzeszutek Wilk 
Cc: Boris Ostrovsky 
Cc: David Vrabel 
Cc: Juergen Gross 
Cc: "Kirill A. Shutemov" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

xen: add static initialization of steal_clock op to xen_time_ops

2016-07-26T13:07:06+00:00

pv_time_ops might be overwritten with xen_time_ops after the
steal_clock operation has been initialized already. To prevent calling
a now uninitialized function pointer add the steal_clock static
initialization to xen_time_ops.

Signed-off-by: Juergen Gross 
Signed-off-by: David Vrabel

xen/evtchn: use xen_vcpu_id mapping

2016-07-25T12:34:18+00:00

Use the newly introduced xen_vcpu_id mapping to get Xen's idea of vCPU
id for CPU0.

Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: David Vrabel

xen/events: fifo: use xen_vcpu_id mapping

2016-07-25T12:34:12+00:00

EVTCHNOP_init_control has vCPU id as a parameter and Xen's idea of
vCPU id should be used. Use the newly introduced xen_vcpu_id mapping
to convert it from Linux's id.

Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: David Vrabel

xen/events: use xen_vcpu_id mapping in events_base

2016-07-25T12:34:06+00:00

EVTCHNOP_bind_ipi and EVTCHNOP_bind_virq pass vCPU id as a parameter
and Xen's idea of vCPU id should be used. Use the newly introduced
xen_vcpu_id mapping to convert it from Linux's id.

Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: David Vrabel

x86/xen: use xen_vcpu_id mapping for HYPERVISOR_vcpu_op

2016-07-25T12:32:34+00:00

HYPERVISOR_vcpu_op() passes Linux's idea of vCPU id as a parameter
while Xen's idea is expected. In some cases these ideas diverge so we
need to do remapping.

Convert all callers of HYPERVISOR_vcpu_op() to use xen_vcpu_nr().

Leave xen_fill_possible_map() and xen_filter_cpu_maps() intact as
they're only being called by PV guests before perpu areas are
initialized. While the issue could be solved by switching to
early_percpu for xen_vcpu_id I think it's not worth it: PV guests will
probably never get to the point where their idea of vCPU id diverges
from Xen's.

Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: David Vrabel