kernel.git/include/xen/grant_table.h, branch linux-5.12.y

Xen/gnttab: introduce common INVALID_GRANT_{HANDLE,REF}

2021-03-10T22:39:29Z

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 Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/db7c38a5-0d75-d5d1-19de-e5fe9f0b9c48@suse.com Signed-off-by: Boris Ostrovsky

Xen/gntdev: correct error checking in gntdev_map_grant_pages()

2021-02-15T07:52:27Z

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 Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross

xen: don't use page->lru for ZONE_DEVICE memory

2020-12-09T09:31:41Z

Commit 9e2369c06c8a18 ("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: # 5.9 Fixes: 9e2369c06c8a18 ("xen: add helpers to allocate unpopulated memory") Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Reviewed-by: Jason Andryuk Signed-off-by: Juergen Gross

xen: add helpers for caching grant mapping pages

2020-12-09T09:31:37Z

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

xen/grant-table: Allow allocating buffers suitable for DMA

2018-07-27T03:05:14Z

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

xen/grant-table: Make set/clear page private code shared

2018-07-27T03:05:13Z

Make set/clear page private code shared and accessible to other kernel modules which can re-use these instead of open-coding. Signed-off-by: Oleksandr Andrushchenko Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky

xen: limit grant v2 interface to the v1 functionality

2017-11-06T20:50:17Z

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

xen: re-introduce support for grant v2 interface

2017-11-06T20:50:17Z

The grant v2 support was removed from the kernel with commit 438b33c7145ca8a5131a30c36d8f59bce119a19a ("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 Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky

xen/grant-table: Add an helper to iterate over a specific number of grants

2015-10-23T13:20:46Z

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 Signed-off-by: David Vrabel

xen/grant: Add helper gnttab_page_grant_foreign_access_ref_one

2015-10-23T13:20:34Z

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 Reviewed-by: David Vrabel Reviewed-by: Stefano Stabellini Signed-off-by: David Vrabel