kernel/linux.git/include/xen, branch v5.18.2

xen/grant-table: remove readonly parameter from functions

2022-03-16T01:34:40+00:00

The gnttab_end_foreign_access() family of functions is taking a "readonly" parameter, which isn't used. Remove it from the function parameters. Signed-off-by: Juergen Gross Link: https://lore.kernel.org/r/20220311103429.12845-3-jgross@suse.com Reviewed-by: Jan Beulich Acked-by: Christian Schoenebeck Signed-off-by: Boris Ostrovsky

xen/grant-table: remove gnttab_transfer() functions

2022-03-16T01:34:04+00:00

All grant table operations related to the "transfer" functionality are unused currently. There have been users in the old days of the "Xen-o-Linux" kernel, but those didn't make it upstream. So remove the "transfer" related functions. Signed-off-by: Juergen Gross Link: https://lore.kernel.org/r/20220311103429.12845-2-jgross@suse.com Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky

xen/gnttab: fix gnttab_end_foreign_access() without page specified

2022-03-07T08:48:55+00:00

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 Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich --- V4: - expand comment in header V5: - get page ref in case of kmalloc() failure, too

xen: remove gnttab_query_foreign_access()

2022-03-07T08:48:54+00:00

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 Reviewed-by: Jan Beulich

xen/grant-table: add gnttab_try_end_foreign_access()

2022-03-07T08:48:54+00:00

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 Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich --- V2: - new patch V4: - add comments to header (Jan Beulich)

xen: xenbus_dev.h: delete incorrect file name

2022-02-03T07:16:32+00:00

It is better/preferred not to include file names in source files because (a) they are not needed and (b) they can be incorrect, so just delete this incorrect file name. Signed-off-by: Randy Dunlap Reviewed-by: Juergen Gross Cc: Boris Ostrovsky Cc: Juergen Gross Cc: Stefano Stabellini Cc: xen-devel@lists.xenproject.org Link: https://lore.kernel.org/r/20220130191705.24971-1-rdunlap@infradead.org Signed-off-by: Juergen Gross

Merge tag 'for-linus-5.17-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2022-01-13T00:42:00+00:00

Pull xen updates from Juergen Gross: - a fix for the Xen gntdev driver - a fix for running as Xen dom0 booted via EFI and the EFI framebuffer being located above 4GB - a series for support of mapping other guest's memory by using zone device when running as Xen guest on Arm * tag 'for-linus-5.17-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: dt-bindings: xen: Clarify "reg" purpose arm/xen: Read extended regions from DT and init Xen resource xen/unpopulated-alloc: Add mechanism to use Xen resource xen/balloon: Bring alloc(free)_xenballooned_pages helpers back arm/xen: Switch to use gnttab_setup_auto_xlat_frames() for DT xen/unpopulated-alloc: Drop check for virt_addr_valid() in fill_list() xen/x86: obtain upper 32 bits of video frame buffer address for Dom0 xen/gntdev: fix unmap notification order

xen/unpopulated-alloc: Add mechanism to use Xen resource

2022-01-06T08:53:38+00:00

The main reason of this change is that unpopulated-alloc code cannot be used in its current form on Arm, but there is a desire to reuse it to avoid wasting real RAM pages for the grant/foreign mappings. The problem is that system "iomem_resource" is used for the address space allocation, but the really unallocated space can't be figured out precisely by the domain on Arm without hypervisor involvement. For example, not all device I/O regions are known by the time domain starts creating grant/foreign mappings. And following the advise from "iomem_resource" we might end up reusing these regions by a mistake. So, the hypervisor which maintains the P2M for the domain is in the best position to provide unused regions of guest physical address space which could be safely used to create grant/foreign mappings. Introduce new helper arch_xen_unpopulated_init() which purpose is to create specific Xen resource based on the memory regions provided by the hypervisor to be used as unused space for Xen scratch pages. If arch doesn't define arch_xen_unpopulated_init() the default "iomem_resource" will be used. Update the arguments list of allocate_resource() in fill_list() to always allocate a region from the hotpluggable range (maximum possible addressable physical memory range for which the linear mapping could be created). If arch doesn't define arch_get_mappable_range() the default range (0,-1) will be used. The behaviour on x86 won't be changed by current patch as both arch_xen_unpopulated_init() and arch_get_mappable_range() are not implemented for it. Also fallback to allocate xenballooned pages (balloon out RAM pages) if we do not have any suitable resource to work with (target_resource is invalid) and as the result we won't be able to provide unpopulated pages on a request. Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/1639080336-26573-5-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross

xen/balloon: Bring alloc(free)_xenballooned_pages helpers back

2022-01-06T08:53:35+00:00

This patch rolls back some of the changes introduced by commit 121f2faca2c0a "xen/balloon: rename alloc/free_xenballooned_pages" in order to make possible to still allocate xenballooned pages if CONFIG_XEN_UNPOPULATED_ALLOC is enabled. On Arm the unpopulated pages will be allocated on top of extended regions provided by Xen via device-tree (the subsequent patches will add required bits to support unpopulated-alloc feature on Arm). The problem is that extended regions feature has been introduced into Xen quite recently (during 4.16 release cycle). So this effectively means that Linux must only use unpopulated-alloc on Arm if it is running on "new Xen" which advertises these regions. But, it will only be known after parsing the "hypervisor" node at boot time, so before doing that we cannot assume anything. In order to keep working if CONFIG_XEN_UNPOPULATED_ALLOC is enabled and the extended regions are not advertised (Linux is running on "old Xen", etc) we need the fallback to alloc_xenballooned_pages(). This way we wouldn't reduce the amount of memory usable (wasting RAM pages) for any of the external mappings anymore (and eliminate XSA-300) with "new Xen", but would be still functional ballooning out RAM pages with "old Xen". Also rename alloc(free)_xenballooned_pages to xen_alloc(free)_ballooned_pages and make xen_alloc(free)_unpopulated_pages static inline in xen.h if CONFIG_XEN_UNPOPULATED_ALLOC is disabled. Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/1639080336-26573-4-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross

xen/x86: obtain upper 32 bits of video frame buffer address for Dom0

2022-01-06T07:55:34+00:00

The hypervisor has been supplying this information for a couple of major releases. Make use of it. The need to set a flag in the capabilities field also points out that the prior setting of that field from the hypervisor interface's gbl_caps one was wrong, so that code gets deleted (there's also no equivalent of this in native boot code). Signed-off-by: Jan Beulich Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/a3df8bf3-d044-b7bb-3383-cd5239d6d4af@suse.com Signed-off-by: Juergen Gross