In current linux.git, gnttab_suspend() and gnttab_resume() are defined
and declared unconditionally. However, their only in-tree callers reside
in drivers/xen/manage.c, which are guarded by CONFIG_HIBERNATE_CALLBACKS.
Match the helper scope to their callers by wrapping the definitions in
CONFIG_HIBERNATE_CALLBACKS and providing no-op stubs in the header. This
fixes the config-scope mismatch and reduces the code footprint when
hibernation callbacks are disabled.
Signed-off-by: Pengpeng Hou <pengpeng.hou@isrc.iscas.ac.cn>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <20260310080800.742223-1-pengpeng.hou@isrc.iscas.ac.cn>
Instead of testing the XENFEAT_auto_translated_physmap feature, just
use !xen_pv_domain() which is equivalent.
This has the advantage that a kernel not built with CONFIG_XEN_PV
will be smaller due to dead code elimination.
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <20250826145608.10352-3-jgross@suse.com>
For support of virtio via grant mappings in rare cases larger mappings
using consecutive grants are needed. Support those by adding a bitmap
of free grants.
As consecutive grants will be needed only in very rare cases (e.g. when
configuring a virtio device with a multi-page ring), optimize for the
normal case of non-consecutive allocations.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/1654197833-25362-3-git-send-email-olekstysh@gmail.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Instead of a virtual kernel address use a pointer of the associated
struct page as second parameter of gnttab_end_foreign_access().
Most users have that pointer available already and are creating the
virtual address from it, risking problems in case the memory is
located in highmem.
gnttab_end_foreign_access() itself won't need to get the struct page
from the address again.
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Update include/xen/interface/grant_table.h to its newest version.
This allows to drop some private definitions in grant-table.c and
include/xen/grant_table.h.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
gnttab_end_foreign_access() is used to free a grant reference and
optionally to free the associated page. In case the grant is still in
use by the other side processing is being deferred. This leads to a
problem in case no page to be freed is specified by the caller: the
caller doesn't know that the page is still mapped by the other side
and thus should not be used for other purposes.
The correct way to handle this situation is to take an additional
reference to the granted page in case handling is being deferred and
to drop that reference when the grant reference could be freed
finally.
This requires that there are no users of gnttab_end_foreign_access()
left directly repurposing the granted page after the call, as this
might result in clobbered data or information leaks via the not yet
freed grant reference.
This is part of CVE-2022-23041 / XSA-396.
Reported-by: Simon Gaiser <simon@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
V4:
- expand comment in header
V5:
- get page ref in case of kmalloc() failure, too
Remove gnttab_query_foreign_access(), as it is unused and unsafe to
use.
All previous use cases assumed a grant would not be in use after
gnttab_query_foreign_access() returned 0. This information is useless
in best case, as it only refers to a situation in the past, which could
have changed already.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Add a new grant table function gnttab_try_end_foreign_access(), which
will remove and free a grant if it is not in use.
Its main use case is to either free a grant if it is no longer in use,
or to take some other action if it is still in use. This other action
can be an error exit, or (e.g. in the case of blkfront persistent grant
feature) some special handling.
This is CVE-2022-23036, CVE-2022-23038 / part of XSA-396.
Reported-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
V2:
- new patch
V4:
- add comments to header (Jan Beulich)
It's not helpful if every driver has to cook its own. Generalize
xenbus'es INVALID_GRANT_HANDLE and pcifront's INVALID_GRANT_REF (which
shouldn't have expanded to zero to begin with). Use the constants in
p2m.c and gntdev.c right away, and update field types where necessary so
they would match with the constants' types (albeit without touching
struct ioctl_gntdev_grant_ref's ref field, as that's part of the public
interface of the kernel and would require introducing a dependency on
Xen's grant_table.h public header).
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/db7c38a5-0d75-d5d1-19de-e5fe9f0b9c48@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Failure of the kernel part of the mapping operation should also be
indicated as an error to the caller, or else it may assume the
respective kernel VA is okay to access.
Furthermore gnttab_map_refs() failing still requires recording
successfully mapped handles, so they can be unmapped subsequently. This
in turn requires there to be a way to tell full hypercall failure from
partial success - preset map_op status fields such that they won't
"happen" to look as if the operation succeeded.
Also again use GNTST_okay instead of implying its value (zero).
This is part of XSA-361.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Commit 9e2369c06c ("xen: add helpers to allocate unpopulated
memory") introduced usage of ZONE_DEVICE memory for foreign memory
mappings.
Unfortunately this collides with using page->lru for Xen backend
private page caches.
Fix that by using page->zone_device_data instead.
Cc: <stable@vger.kernel.org> # 5.9
Fixes: 9e2369c06c ("xen: add helpers to allocate unpopulated memory")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovksy@oracle.com>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Instead of having similar helpers in multiple backend drivers use
common helpers for caching pages allocated via gnttab_alloc_pages().
Make use of those helpers in blkback and scsiback.
Cc: <stable@vger.kernel.org> # 5.9
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovksy@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Extend grant table module API to allow allocating buffers that can
be used for DMA operations and mapping foreign grant references
on top of those.
The resulting buffer is similar to the one allocated by the balloon
driver in that proper memory reservation is made by
({increase|decrease}_reservation and VA mappings are updated if
needed).
This is useful for sharing foreign buffers with HW drivers which
cannot work with scattered buffers provided by the balloon driver,
but require DMAable memory instead.
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
As there is currently no user for sub-page grants or transient grants
remove that functionality. This at once makes it possible to switch
from grant v2 to grant v1 without restrictions, as there is no loss of
functionality other than the limited frame number width related to
the switch.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
The grant v2 support was removed from the kernel with
commit 438b33c714 ("xen/grant-table:
remove support for V2 tables") as the higher memory footprint of v2
grants resulted in less grants being possible for a kernel compared
to the v1 grant interface.
As machines with more than 16TB of memory are expected to be more
common in the near future support of grant v2 is mandatory in order
to be able to run a Xen pv domain at any memory location.
So re-add grant v2 support basically by reverting above commit.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
With the 64KB page granularity support on ARM64, a Linux page may be
split accross multiple grant.
Currently we have the helper gnttab_foreach_grant_in_grant to break a
Linux page based on an offset and a len, but it doesn't fit when we only
have a number of grants in hand.
Introduce a new helper which take an array of Linux page and a number of
grant and will figure out the address of each grant.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Many PV drivers contain the idiom:
pfn = page_to_gfn(...) /* Or similar */
gnttab_grant_foreign_access_ref
Replace it by a new helper. Note that when Linux is using a different
page granularity than Xen, the helper only gives access to the first 4KB
grant.
This is useful where drivers are allocating a full Linux page for each
grant.
Also include xen/interface/grant_table.h rather than xen/grant_table.h in
asm/page.h for x86 to fix a compilation issue [1]. Only the former is
useful in order to get the structure definition.
[1] Interdependency between asm/page.h and xen/grant_table.h which result
to page_mfn not being defined when necessary.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Currently, a grant is always based on the Xen page granularity (i.e
4KB). When Linux is using a different page granularity, a single page
will be split between multiple grants.
The new helpers will be in charge of splitting the Linux page into grants
and call a function given by the caller on each grant.
Also provide an helper to count the number of grants within a given
contiguous region.
Note that the x86/include/asm/xen/page.h is now including
xen/interface/grant_table.h rather than xen/grant_table.h. It's
necessary because xen/grant_table.h depends on asm/xen/page.h and will
break the compilation. Furthermore, only definition in
interface/grant_table.h is required.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Introduce gnttab_unmap_refs_async() that can be used to safely unmap
pages that may be in use (ref count > 1). If the pages are in use the
unmap is deferred and retried later. This polling is not very clever
but it should be good enough if the cases where the delay is necessary
are rare.
The initial delay is 5 ms and is increased linearly on each subsequent
retry (to reduce load if the page is in use for a long time).
This is needed to allow block backends using grant mapping to safely
use network storage (block or filesystem based such as iSCSI or NFS).
The network storage driver may complete a block request whilst there
is a queued network packet retry (because the ack from the remote end
races with deciding to queue the retry). The pages for the retried
packet would be grant unmapped and the network driver (or hardware)
would access the unmapped page.
Signed-off-by: Jennifer Herbert <jennifer.herbert@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Use the "foreign" page flag to mark pages that have a grant map. Use
page->private to store information of the grant (the granting domain
and the grant reference).
Signed-off-by: Jennifer Herbert <jennifer.herbert@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Add gnttab_alloc_pages() and gnttab_free_pages() to allocate/free pages
suitable to for granted maps.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
