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2022-01-06arm/xen: Read extended regions from DT and init Xen resourceOleksandr Tyshchenko1-1/+1
This patch implements arch_xen_unpopulated_init() on Arm where the extended regions (if any) are gathered from DT and inserted into specific Xen resource to be used as unused address space for Xen scratch pages by unpopulated-alloc code. The extended region (safe range) is a region of guest physical address space which is unused and could be safely used to create grant/foreign mappings instead of wasting real RAM pages from the domain memory for establishing these mappings. The extended regions are chosen by the hypervisor at the domain creation time and advertised to it via "reg" property under hypervisor node in the guest device-tree. As region 0 is reserved for grant table space (always present), the indexes for extended regions are 1...N. If arch_xen_unpopulated_init() fails for some reason the default behaviour will be restored (allocate xenballooned pages). This patch also removes XEN_UNPOPULATED_ALLOC dependency on x86. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1639080336-26573-6-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-01-06xen/unpopulated-alloc: Add mechanism to use Xen resourceOleksandr Tyshchenko1-4/+82
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 <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1639080336-26573-5-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-01-06xen/balloon: Bring alloc(free)_xenballooned_pages helpers backOleksandr Tyshchenko1-11/+9
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 <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1639080336-26573-4-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-01-06xen/unpopulated-alloc: Drop check for virt_addr_valid() in fill_list()Oleksandr Tyshchenko1-1/+0
If memremap_pages() succeeds the range is guaranteed to have proper page table, there is no need for an additional virt_addr_valid() check. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/1639080336-26573-2-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-01-06xen/gntdev: fix unmap notification orderOleksandr Andrushchenko1-3/+3
While working with Xen's libxenvchan library I have faced an issue with unmap notifications sent in wrong order if both UNMAP_NOTIFY_SEND_EVENT and UNMAP_NOTIFY_CLEAR_BYTE were requested: first we send an event channel notification and then clear the notification byte which renders in the below inconsistency (cli_live is the byte which was requested to be cleared on unmap): [ 444.514243] gntdev_put_map UNMAP_NOTIFY_SEND_EVENT map->notify.event 6 libxenvchan_is_open cli_live 1 [ 444.515239] __unmap_grant_pages UNMAP_NOTIFY_CLEAR_BYTE at 14 Thus it is not possible to reliably implement the checks like - wait for the notification (UNMAP_NOTIFY_SEND_EVENT) - check the variable (UNMAP_NOTIFY_CLEAR_BYTE) because it is possible that the variable gets checked before it is cleared by the kernel. To fix that we need to re-order the notifications, so the variable is first gets cleared and then the event channel notification is sent. With this fix I can see the correct order of execution: [ 54.522611] __unmap_grant_pages UNMAP_NOTIFY_CLEAR_BYTE at 14 [ 54.537966] gntdev_put_map UNMAP_NOTIFY_SEND_EVENT map->notify.event 6 libxenvchan_is_open cli_live 0 Cc: stable@vger.kernel.org Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20211210092817.580718-1-andr2000@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-12-16xen/console: harden hvc_xen against event channel stormsJuergen Gross1-0/+6
The Xen console driver is still vulnerable for an attack via excessive number of events sent by the backend. Fix that by using a lateeoi event channel. For the normal domU initial console this requires the introduction of bind_evtchn_to_irq_lateeoi() as there is no xenbus device available at the time the event channel is bound to the irq. As the decision whether an interrupt was spurious or not requires to test for bytes having been read from the backend, move sending the event into the if statement, as sending an event without having found any bytes to be read is making no sense at all. This is part of XSA-391 Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> --- V2: - slightly adapt spurious irq detection (Jan Beulich) V3: - fix spurious irq detection (Jan Beulich)
2021-11-24xen: detect uninitialized xenbus in xenbus_initStefano Stabellini1-0/+23
If the xenstore page hasn't been allocated properly, reading the value of the related hvm_param (HVM_PARAM_STORE_PFN) won't actually return error. Instead, it will succeed and return zero. Instead of attempting to xen_remap a bad guest physical address, detect this condition and return early. Note that although a guest physical address of zero for HVM_PARAM_STORE_PFN is theoretically possible, it is not a good choice and zero has never been validly used in that capacity. Also recognize all bits set as an invalid value. For 32-bit Linux, any pfn above ULONG_MAX would get truncated. Pfns above ULONG_MAX should never be passed by the Xen tools to HVM guests anyway, so check for this condition and return early. Cc: stable@vger.kernel.org Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com> Reviewed-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> Link: https://lore.kernel.org/r/20211123210748.1910236-1-sstabellini@kernel.org Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-23xen: flag pvcalls-front to be not essential for system bootJuergen Gross1-0/+1
The Xen pvcalls device is not essential for booting. Set the respective flag. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20211022064800.14978-5-jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-23xen: add "not_essential" flag to struct xenbus_driverJuergen Gross1-11/+3
When booting the xenbus driver will wait for PV devices to have connected to their backends before continuing. The timeout is different between essential and non-essential devices. Non-essential devices are identified by their nodenames directly in the xenbus driver, which requires to update this list in case a new device type being non-essential is added (this was missed for several types in the past). In order to avoid this problem, add a "not_essential" flag to struct xenbus_driver which can be set to "true" by the respective frontend. Set this flag for the frontends currently regarded to be not essential (vkbs and vfb) and use it for testing in the xenbus driver. Signed-off-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20211022064800.14978-2-jgross@suse.com Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-16xen: don't continue xenstore initialization in case of errorsStefano Stabellini1-1/+3
In case of errors in xenbus_init (e.g. missing xen_store_gfn parameter), we goto out_error but we forget to reset xen_store_domain_type to XS_UNKNOWN. As a consequence xenbus_probe_initcall and other initcalls will still try to initialize xenstore resulting into a crash at boot. [ 2.479830] Call trace: [ 2.482314] xb_init_comms+0x18/0x150 [ 2.486354] xs_init+0x34/0x138 [ 2.489786] xenbus_probe+0x4c/0x70 [ 2.498432] xenbus_probe_initcall+0x2c/0x7c [ 2.503944] do_one_initcall+0x54/0x1b8 [ 2.507358] kernel_init_freeable+0x1ac/0x210 [ 2.511617] kernel_init+0x28/0x130 [ 2.516112] ret_from_fork+0x10/0x20 Cc: <Stable@vger.kernel.org> Cc: jbeulich@suse.com Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com> Link: https://lore.kernel.org/r/20211115222719.2558207-1-sstabellini@kernel.org Reviewed-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-16xen/privcmd: make option visible in KconfigJuergen Gross1-1/+7
This configuration option provides a misc device as an API to userspace. Make this API usable without having to select the module as a transitive dependency. This also fixes an issue where localyesconfig would select CONFIG_XEN_PRIVCMD=m because it was not visible and defaulted to building as module. [boris: clarified help message per Jan's suggestion] Based-on-patch-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20211116143323.18866-1-jgross@suse.com Reviewed-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-10Merge tag 'for-linus-5.16b-rc1-tag' of ↵Linus Torvalds13-63/+219
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen updates from Juergen Gross: - a series to speed up the boot of Xen PV guests - some cleanups in Xen related code - replacement of license texts with the appropriate SPDX headers and fixing of wrong SPDX headers in Xen header files - a small series making paravirtualized interrupt masking much simpler and at the same time removing complaints of objtool - a fix for Xen ballooning hogging workqueues for too long - enablement of the Xen pciback driver for Arm - some further small fixes/enhancements * tag 'for-linus-5.16b-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: (22 commits) xen/balloon: fix unused-variable warning xen/balloon: rename alloc/free_xenballooned_pages xen/balloon: add late_initcall_sync() for initial ballooning done x86/xen: remove 32-bit awareness from startup_xen xen: remove highmem remnants xen: allow pv-only hypercalls only with CONFIG_XEN_PV x86/xen: remove 32-bit pv leftovers xen-pciback: allow compiling on other archs than x86 x86/xen: switch initial pvops IRQ functions to dummy ones x86/xen: remove xen_have_vcpu_info_placement flag x86/pvh: add prototype for xen_pvh_init() xen: Fix implicit type conversion xen: fix wrong SPDX headers of Xen related headers xen/pvcalls-back: Remove redundant 'flush_workqueue()' calls x86/xen: Remove redundant irq_enter/exit() invocations xen-pciback: Fix return in pm_ctrl_init() xen/x86: restrict PV Dom0 identity mapping xen/x86: there's no highmem anymore in PV mode xen/x86: adjust handling of the L3 user vsyscall special page table xen/x86: adjust xen_set_fixmap() ...
2021-11-08xen/balloon: fix unused-variable warningArnd Bergmann1-2/+3
In configurations with CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=n and CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y, gcc warns about an unused variable: drivers/xen/balloon.c:83:12: error: 'xen_hotplug_unpopulated' defined but not used [-Werror=unused-variable] Since this is always zero when CONFIG_XEN_BALLOON_MEMORY_HOTPLUG is disabled, turn it into a preprocessor constant in that case. Fixes: 121f2faca2c0 ("xen/balloon: rename alloc/free_xenballooned_pages") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20211108111408.3940366-1-arnd@kernel.org Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-06Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-1/+1
Merge misc updates from Andrew Morton: "257 patches. Subsystems affected by this patch series: scripts, ocfs2, vfs, and mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache, gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc, pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools, memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm, vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram, cleanups, kfence, and damon)" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (257 commits) mm/damon: remove return value from before_terminate callback mm/damon: fix a few spelling mistakes in comments and a pr_debug message mm/damon: simplify stop mechanism Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions Docs/admin-guide/mm/damon/start: simplify the content Docs/admin-guide/mm/damon/start: fix a wrong link Docs/admin-guide/mm/damon/start: fix wrong example commands mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on mm/damon: remove unnecessary variable initialization Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM) selftests/damon: support watermarks mm/damon/dbgfs: support watermarks mm/damon/schemes: activate schemes based on a watermarks mechanism tools/selftests/damon: update for regions prioritization of schemes mm/damon/dbgfs: support prioritization weights mm/damon/vaddr,paddr: support pageout prioritization mm/damon/schemes: prioritize regions within the quotas mm/damon/selftests: support schemes quotas mm/damon/dbgfs: support quotas of schemes ...
2021-11-06memblock: use memblock_free for freeing virtual pointersMike Rapoport1-1/+1
Rename memblock_free_ptr() to memblock_free() and use memblock_free() when freeing a virtual pointer so that memblock_free() will be a counterpart of memblock_alloc() The callers are updated with the below semantic patch and manual addition of (void *) casting to pointers that are represented by unsigned long variables. @@ identifier vaddr; expression size; @@ ( - memblock_phys_free(__pa(vaddr), size); + memblock_free(vaddr, size); | - memblock_free_ptr(vaddr, size); + memblock_free(vaddr, size); ) [sfr@canb.auug.org.au: fixup] Link: https://lkml.kernel.org/r/20211018192940.3d1d532f@canb.auug.org.au Link: https://lkml.kernel.org/r/20210930185031.18648-7-rppt@kernel.org Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Juergen Gross <jgross@suse.com> Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-06memblock: rename memblock_free to memblock_phys_freeMike Rapoport1-1/+1
Since memblock_free() operates on a physical range, make its name reflect it and rename it to memblock_phys_free(), so it will be a logical counterpart to memblock_phys_alloc(). The callers are updated with the below semantic patch: @@ expression addr; expression size; @@ - memblock_free(addr, size); + memblock_phys_free(addr, size); Link: https://lkml.kernel.org/r/20210930185031.18648-6-rppt@kernel.org Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Juergen Gross <jgross@suse.com> Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-04Merge tag 'iommu-updates-v5.16' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu Pull iommu updates from Joerg Roedel: - Intel IOMMU Updates fro Lu Baolu: - Dump DMAR translation structure when DMA fault occurs - An optimization in the page table manipulation code - Use second level for GPA->HPA translation - Various cleanups - Arm SMMU Updates from Will - Minor optimisations to SMMUv3 command creation and submission - Numerous new compatible string for Qualcomm SMMUv2 implementations - Fixes for the SWIOTLB based implemenation of dma-iommu code for untrusted devices - Add support for r8a779a0 to the Renesas IOMMU driver and DT matching code for r8a77980 - A couple of cleanups and fixes for the Apple DART IOMMU driver - Make use of generic report_iommu_fault() interface in the AMD IOMMU driver - Various smaller fixes and cleanups * tag 'iommu-updates-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (35 commits) iommu/dma: Fix incorrect error return on iommu deferred attach iommu/dart: Initialize DART_STREAMS_ENABLE iommu/dma: Use kvcalloc() instead of kvzalloc() iommu/tegra-smmu: Use devm_bitmap_zalloc when applicable iommu/dart: Use kmemdup instead of kzalloc and memcpy iommu/vt-d: Avoid duplicate removing in __domain_mapping() iommu/vt-d: Convert the return type of first_pte_in_page to bool iommu/vt-d: Clean up unused PASID updating functions iommu/vt-d: Delete dev_has_feat callback iommu/vt-d: Use second level for GPA->HPA translation iommu/vt-d: Check FL and SL capability sanity in scalable mode iommu/vt-d: Remove duplicate identity domain flag iommu/vt-d: Dump DMAR translation structure when DMA fault occurs iommu/vt-d: Do not falsely log intel_iommu is unsupported kernel option iommu/arm-smmu-qcom: Request direct mapping for modem device iommu: arm-smmu-qcom: Add compatible for QCM2290 dt-bindings: arm-smmu: Add compatible for QCM2290 SoC iommu/arm-smmu-qcom: Add SM6350 SMMU compatible dt-bindings: arm-smmu: Add compatible for SM6350 SoC iommu/arm-smmu-v3: Properly handle the return value of arm_smmu_cmdq_build_cmd() ...
2021-11-04xen/balloon: rename alloc/free_xenballooned_pagesJuergen Gross1-11/+13
alloc_xenballooned_pages() and free_xenballooned_pages() are used as direct replacements of xen_alloc_unpopulated_pages() and xen_free_unpopulated_pages() in case CONFIG_XEN_UNPOPULATED_ALLOC isn't defined. Guard both functions with !CONFIG_XEN_UNPOPULATED_ALLOC and rename them to the xen_*() variants they are replacing. This allows to remove some ifdeffery from the xen.h header file. Adapt the prototype of the functions to match. Signed-off-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20211102092234.17852-1-jgross@suse.com Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-04xen/balloon: add late_initcall_sync() for initial ballooning doneJuergen Gross1-23/+63
When running as PVH or HVM guest with actual memory < max memory the hypervisor is using "populate on demand" in order to allow the guest to balloon down from its maximum memory size. For this to work correctly the guest must not touch more memory pages than its target memory size as otherwise the PoD cache will be exhausted and the guest is crashed as a result of that. In extreme cases ballooning down might not be finished today before the init process is started, which can consume lots of memory. In order to avoid random boot crashes in such cases, add a late init call to wait for ballooning down having finished for PVH/HVM guests. Warn on console if initial ballooning fails, panic() after stalling for more than 3 minutes per default. Add a module parameter for changing this timeout. [boris: replaced pr_info() with pr_notice()] Cc: <stable@vger.kernel.org> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> Signed-off-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20211102091944.17487-1-jgross@suse.com Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-02x86/xen: remove 32-bit pv leftoversJuergen Gross1-17/+10
There are some remaining 32-bit pv-guest support leftovers in the Xen hypercall interface. Remove them. Signed-off-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20211028081221.2475-2-jgross@suse.com Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-02xen-pciback: allow compiling on other archs than x86Oleksandr Andrushchenko8-6/+127
Xen-pciback driver was designed to be built for x86 only. But it can also be used by other architectures, e.g. Arm. Currently PCI backend implements multiple functionalities at a time, such as: 1. It is used as a database for assignable PCI devices, e.g. xl pci-assignable-{add|remove|list} manipulates that list. So, whenever the toolstack needs to know which PCI devices can be passed through it reads that from the relevant sysfs entries of the pciback. 2. It is used to hold the unbound PCI devices list, e.g. when passing through a PCI device it needs to be unbound from the relevant device driver and bound to pciback (strictly speaking it is not required that the device is bound to pciback, but pciback is again used as a database of the passed through PCI devices, so we can re-bind the devices back to their original drivers when guest domain shuts down) 3. Device reset for the devices being passed through 4. Para-virtualised use-cases support The para-virtualised part of the driver is not always needed as some architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend model for PCI device passthrough. For such use-cases make the very first step in splitting the xen-pciback driver into two parts: Xen PCI stub and PCI PV backend drivers. For that add new configuration options CONFIG_XEN_PCI_STUB and CONFIG_XEN_PCIDEV_STUB, so the driver can be limited in its functionality, e.g. no support for para-virtualised scenario. x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the fully featured backend driver. Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20211028143620.144936-1-andr2000@gmail.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-02xen: Fix implicit type conversionJiasheng Jiang1-3/+3
The variable 'i' is defined as UINT. However, in the for_each_possible_cpu its value is assigned to -1. That doesn't make sense and in the cpumask_next() it is implicitly type converted to INT. It is universally accepted that the implicit type conversion is terrible. Also, having the good programming custom will set an example for others. Thus, it might be better to change the definition of 'i' from UINT to INT. [boris: fixed commit message formatting] Fixes: 3fac10145b76 ("xen: Re-upload processor PM data to hypervisor after S3 resume (v2)") Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn> Link: https://lore.kernel.org/r/1635233531-2437704-1-git-send-email-jiasheng@iscas.ac.cn Reviewed-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jiamei Xie <jiamei.xie@arm.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-02xen/pvcalls-back: Remove redundant 'flush_workqueue()' callsChristophe JAILLET1-1/+0
'destroy_workqueue()' already drains the queue before destroying it, so there is no need to flush it explicitly. Remove the redundant 'flush_workqueue()' calls. This was generated with coccinelle: @@ expression E; @@ - flush_workqueue(E); destroy_workqueue(E); Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Acked-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/2d6c2e031e4aa2acf2ac4e0bbbc17cfdcc8dbee2.1634236560.git.christophe.jaillet@wanadoo.fr Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-02xen-pciback: Fix return in pm_ctrl_init()YueHaibing1-1/+1
Return NULL instead of passing to ERR_PTR while err is zero, this fix smatch warnings: drivers/xen/xen-pciback/conf_space_capability.c:163 pm_ctrl_init() warn: passing zero to 'ERR_PTR' Fixes: a92336a1176b ("xen/pciback: Drop two backends, squash and cleanup some code.") Signed-off-by: YueHaibing <yuehaibing@huawei.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20211008074417.8260-1-yuehaibing@huawei.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-10-31Merge branches 'apple/dart', 'arm/mediatek', 'arm/renesas', 'arm/smmu', ↵Joerg Roedel1-1/+1
'arm/tegra', 'iommu/fixes', 'x86/amd', 'x86/vt-d' and 'core' into next
2021-10-25dma-buf: move dma-buf symbols into the DMA_BUF module namespaceGreg Kroah-Hartman1-0/+3
In order to better track where in the kernel the dma-buf code is used, put the symbols in the namespace DMA_BUF and modify all users of the symbols to properly import the namespace to not break the build at the same time. Now the output of modinfo shows the use of these symbols, making it easier to watch for users over time: $ modinfo drivers/misc/fastrpc.ko | grep import import_ns: DMA_BUF Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com> Cc: David Airlie <airlied@linux.ie> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: dri-devel@lists.freedesktop.org Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> Acked-by: Alex Deucher <alexander.deucher@amd.com> Link: https://lore.kernel.org/r/20211010124628.17691-1-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-08Merge tag 'for-linus-5.15b-rc5-tag' of ↵Linus Torvalds3-17/+26
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fixes from Juergen Gross: - fix two minor issues in the Xen privcmd driver plus a cleanup patch for that driver - fix multiple issues related to running as PVH guest and some related earlyprintk fixes for other Xen guest types - fix an issue introduced in 5.15 the Xen balloon driver * tag 'for-linus-5.15b-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/balloon: fix cancelled balloon action xen/x86: adjust data placement x86/PVH: adjust function/data placement xen/x86: hook up xen_banner() also for PVH xen/x86: generalize preferred console model from PV to PVH Dom0 xen/x86: make "earlyprintk=xen" work for HVM/PVH DomU xen/x86: allow "earlyprintk=xen" to work for PV Dom0 xen/x86: make "earlyprintk=xen" work better for PVH Dom0 xen/x86: allow PVH Dom0 without XEN_PV=y xen/x86: prevent PVH type from getting clobbered xen/privcmd: drop "pages" parameter from xen_remap_pfn() xen/privcmd: fix error handling in mmap-resource processing xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages
2021-10-06xen/balloon: fix cancelled balloon actionJuergen Gross1-6/+15
In case a ballooning action is cancelled the new kernel thread handling the ballooning might end up in a busy loop. Fix that by handling the cancelled action gracefully. While at it introduce a short wait for the BP_WAIT case. Cc: stable@vger.kernel.org Fixes: 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> Signed-off-by: Juergen Gross <jgross@suse.com> Tested-by: Jason Andryuk <jandryuk@gmail.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20211005133433.32008-1-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-10-05xen/x86: allow PVH Dom0 without XEN_PV=yJan Beulich1-2/+2
Decouple XEN_DOM0 from XEN_PV, converting some existing uses of XEN_DOM0 to a new XEN_PV_DOM0. (I'm not convinced all are really / should really be PV-specific, but for starters I've tried to be conservative.) For PVH Dom0 the hypervisor populates MADT with only x2APIC entries, so without x2APIC support enabled in the kernel things aren't going to work very well. (As opposed, DomU-s would only ever see LAPIC entries in MADT as of now.) Note that this then requires PVH Dom0 to be 64-bit, as X86_X2APIC depends on X86_64. In the course of this xen_running_on_version_or_later() needs to be available more broadly. Move it from a PV-specific to a generic file, considering that what it does isn't really PV-specific at all anyway. Note that xen/interface/version.h cannot be included on its own; in enlighten.c, which uses SCHEDOP_* anyway, include xen/interface/sched.h first to resolve the apparently sole missing type (xen_ulong_t). Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/983bb72f-53df-b6af-14bd-5e088bd06a08@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-10-05xen/privcmd: drop "pages" parameter from xen_remap_pfn()Jan Beulich1-3/+2
The function doesn't use it and all of its callers say in a comment that their respective arguments are to be non-NULL only in auto-translated mode. Since xen_remap_domain_mfn_array() isn't supposed to be used by non-PV, drop the parameter there as well. It was bogusly passed as non- NULL (PRIV_VMA_LOCKED) by its only caller anyway. For xen_remap_domain_gfn_range(), otoh, it's not clear at all why this wouldn't want / might not need to gain auto-translated support down the road, so the parameter is retained there despite now remaining unused (and the only caller passing NULL); correct a respective comment as well. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/036ad8a2-46f9-ac3d-6219-bdc93ab9e10b@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-10-05xen/privcmd: fix error handling in mmap-resource processingJan Beulich1-3/+4
xen_pfn_t is the same size as int only on 32-bit builds (and not even on Arm32). Hence pfns[] can't be used directly to read individual error values returned from xen_remap_domain_mfn_array(); every other error indicator would be skipped/ignored on 64-bit. Fixes: 3ad0876554ca ("xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE") Cc: stable@vger.kernel.org Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/aa6d6a67-6889-338a-a910-51e889f792d5@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-10-05xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pagesJan Beulich1-3/+3
Osstest has been suffering test failures for a little while from order-4 allocation failures, resulting from alloc_empty_pages() calling kcalloc(). As there's no need for physically contiguous space here, switch to kvcalloc(). Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/6d698901-98a4-05be-c421-bcd0713f5335@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-29swiotlb: Support aligned swiotlb buffersDavid Stevens1-1/+1
Add an argument to swiotlb_tbl_map_single that specifies the desired alignment of the allocated buffer. This is used by dma-iommu to ensure the buffer is aligned to the iova granule size when using swiotlb with untrusted sub-granule mappings. This addresses an issue where adjacent slots could be exposed to the untrusted device if IO_TLB_SIZE < iova granule < PAGE_SIZE. Signed-off-by: David Stevens <stevensd@chromium.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210929023300.335969-7-stevensd@google.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-09-25Merge tag 'for-linus-5.15b-rc3-tag' of ↵Linus Torvalds4-5/+15
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fixes from Juergen Gross: "Some minor cleanups and fixes of some theoretical bugs, as well as a fix of a bug introduced in 5.15-rc1" * tag 'for-linus-5.15b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/x86: fix PV trap handling on secondary processors xen/balloon: fix balloon kthread freezing swiotlb-xen: this is PV-only on x86 xen/pci-swiotlb: reduce visibility of symbols PCI: only build xen-pcifront in PV-enabled environments swiotlb-xen: ensure to issue well-formed XENMEM_exchange requests Xen/gntdev: don't ignore kernel unmapping error xen/x86: drop redundant zeroing from cpu_initialize_context()
2021-09-21xen/balloon: fix balloon kthread freezingJuergen Gross1-2/+2
Commit 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") switched the Xen balloon driver to use a kernel thread. Unfortunately the patch omitted to call try_to_freeze() or to use wait_event_freezable_timeout(), causing a system suspend to fail. Fixes: 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20210920100345.21939-1-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-20swiotlb-xen: this is PV-only on x86Jan Beulich1-0/+1
The code is unreachable for HVM or PVH, and it also makes little sense in auto-translated environments. On Arm, with xen_{create,destroy}_contiguous_region() both being stubs, I have a hard time seeing what good the Xen specific variant does - the generic one ought to be fine for all purposes there. Still Arm code explicitly references symbols here, so the code will continue to be included there. Instead of making PCI_XEN's "select" conditional, simply drop it - SWIOTLB_XEN will be available unconditionally in the PV case anyway, and is - as explained above - dead code in non-PV environments. This in turn allows dropping the stubs for xen_{create,destroy}_contiguous_region(), the former of which was broken anyway - it failed to set the DMA handle output. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/5947b8ae-fdc7-225c-4838-84712265fc1e@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-20swiotlb-xen: ensure to issue well-formed XENMEM_exchange requestsJan Beulich1-3/+4
While the hypervisor hasn't been enforcing this, we would still better avoid issuing requests with GFNs not aligned to the requested order. Instead of altering the value also in the call to panic(), drop it there for being static and hence easy to determine without being part of the panic message. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/7b3998e3-1233-4e5a-89ec-d740e77eb166@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-20Xen/gntdev: don't ignore kernel unmapping errorJan Beulich1-0/+8
While working on XSA-361 and its follow-ups, I failed to spot another place where the kernel mapping part of an operation was not treated the same as the user space part. Detect and propagate errors and add a 2nd pr_debug(). Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/c2513395-74dc-aea3-9192-fd265aa44e35@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-17Merge tag 'for-linus-5.15b-rc2-tag' of ↵Linus Torvalds3-38/+63
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fixes from Juergen Gross: - The first hunk of a Xen swiotlb fixup series fixing multiple minor issues and doing some small cleanups - Some further Xen related fixes avoiding WARN() splats when running as Xen guests or dom0 - A Kconfig fix allowing the pvcalls frontend to be built as a module * tag 'for-linus-5.15b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: swiotlb-xen: drop DEFAULT_NSLABS swiotlb-xen: arrange to have buffer info logged swiotlb-xen: drop leftover __ref swiotlb-xen: limit init retries swiotlb-xen: suppress certain init retries swiotlb-xen: maintain slab count properly swiotlb-xen: fix late init retry swiotlb-xen: avoid double free xen/pvcalls: backend can be a module xen: fix usage of pmd_populate in mremap for pv guests xen: reset legacy rtc flag for PV domU PM: base: power: don't try to use non-existing RTC for storing data xen/balloon: use a kernel thread instead a workqueue
2021-09-15swiotlb-xen: drop DEFAULT_NSLABSJan Beulich1-2/+0
It was introduced by 4035b43da6da ("xen-swiotlb: remove xen_set_nslabs") and then not removed by 2d29960af0be ("swiotlb: dynamically allocate io_tlb_default_mem"). Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/15259326-209a-1d11-338c-5018dc38abe8@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15swiotlb-xen: arrange to have buffer info loggedJan Beulich1-1/+1
I consider it unhelpful that address and size of the buffer aren't put in the log file; it makes diagnosing issues needlessly harder. The majority of callers of swiotlb_init() also passes 1 for the "verbose" parameter. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/2e3c8e68-36b2-4ae9-b829-bf7f75d39d47@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15swiotlb-xen: drop leftover __refJan Beulich1-1/+1
Commit a98f565462f0 ("xen-swiotlb: split xen_swiotlb_init") should not only have added __init to the split off function, but also should have dropped __ref from the one left. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/7cd163e1-fe13-270b-384c-2708e8273d34@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15swiotlb-xen: limit init retriesJan Beulich1-2/+2
Due to the use of max(1024, ...) there's no point retrying (and issuing bogus log messages) when the number of slabs is already no larger than this minimum value. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/984fa426-2b7b-4b77-5ce8-766619575b7f@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15swiotlb-xen: suppress certain init retriesJan Beulich1-1/+2
Only on the 2nd of the paths leading to xen_swiotlb_init()'s "error" label it is useful to retry the allocation; the first one did already iterate through all possible order values. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/56477481-87da-4962-9661-5e1b277efde0@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15swiotlb-xen: maintain slab count properlyJan Beulich1-10/+9
Generic swiotlb code makes sure to keep the slab count a multiple of the number of slabs per segment. Yet even without checking whether any such assumption is made elsewhere, it is easy to see that xen_swiotlb_fixup() might alter unrelated memory when calling xen_create_contiguous_region() for the last segment, when that's not a full one - the function acts on full order-N regions, not individual pages. Align the slab count suitably when halving it for a retry. Add a build time check and a runtime one. Replace the no longer useful local variable "slabs" by an "order" one calculated just once, outside of the loop. Re-use "order" for calculating "dma_bits", and change the type of the latter as well as the one of "i" while touching this anyway. Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/dc054cb0-bec4-4db0-fc06-c9fc957b6e66@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15swiotlb-xen: fix late init retryJan Beulich1-2/+2
The commit referenced below removed the assignment of "bytes" from xen_swiotlb_init() without - like done for xen_swiotlb_init_early() - adding an assignment on the retry path, thus leading to excessively sized allocations upon retries. Fixes: 2d29960af0be ("swiotlb: dynamically allocate io_tlb_default_mem") Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: stable@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/778299d6-9cfd-1c13-026e-25ee5d14ecb3@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15swiotlb-xen: avoid double freeJan Beulich1-1/+0
Of the two paths leading to the "error" label in xen_swiotlb_init() one didn't allocate anything, while the other did already free what was allocated. Fixes: b82776005369 ("xen/swiotlb: Use the swiotlb_late_init_with_tbl to init Xen-SWIOTLB late when PV PCI is used") Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: stable@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/ce9c2adb-8a52-6293-982a-0d6ece943ac6@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-15xen/pvcalls: backend can be a moduleJan Beulich1-1/+1
It's not clear to me why only the frontend has been tristate. Switch the backend to be, too. Signed-off-by: Jan Beulich <jbeulich@suse.com> Acked-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/54a6070c-92bb-36a3-2fc0-de9ccca438c5@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-14xen/balloon: use a kernel thread instead a workqueueJuergen Gross1-17/+45
Today the Xen ballooning is done via delayed work in a workqueue. This might result in workqueue hangups being reported in case of large amounts of memory are being ballooned in one go (here 16GB): BUG: workqueue lockup - pool cpus=6 node=0 flags=0x0 nice=0 stuck for 64s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=2/256 refcnt=3 in-flight: 229:balloon_process pending: cache_reap workqueue events_freezable_power_: flags=0x84 pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=1/256 refcnt=2 pending: disk_events_workfn workqueue mm_percpu_wq: flags=0x8 pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=1/256 refcnt=2 pending: vmstat_update pool 12: cpus=6 node=0 flags=0x0 nice=0 hung=64s workers=3 idle: 2222 43 This can easily be avoided by using a dedicated kernel thread for doing the ballooning work. Reported-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20210827123206.15429-1-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2021-09-03Merge tag 'kbuild-v5.15' of ↵Linus Torvalds1-2/+0
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - Add -s option (strict mode) to merge_config.sh to make it fail when any symbol is redefined. - Show a warning if a different compiler is used for building external modules. - Infer --target from ARCH for CC=clang to let you cross-compile the kernel without CROSS_COMPILE. - Make the integrated assembler default (LLVM_IAS=1) for CC=clang. - Add <linux/stdarg.h> to the kernel source instead of borrowing <stdarg.h> from the compiler. - Add Nick Desaulniers as a Kbuild reviewer. - Drop stale cc-option tests. - Fix the combination of CONFIG_TRIM_UNUSED_KSYMS and CONFIG_LTO_CLANG to handle symbols in inline assembly. - Show a warning if 'FORCE' is missing for if_changed rules. - Various cleanups * tag 'kbuild-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (39 commits) kbuild: redo fake deps at include/ksym/*.h kbuild: clean up objtool_args slightly modpost: get the *.mod file path more simply checkkconfigsymbols.py: Fix the '--ignore' option kbuild: merge vmlinux_link() between ARCH=um and other architectures kbuild: do not remove 'linux' link in scripts/link-vmlinux.sh kbuild: merge vmlinux_link() between the ordinary link and Clang LTO kbuild: remove stale *.symversions kbuild: remove unused quiet_cmd_update_lto_symversions gen_compile_commands: extract compiler command from a series of commands x86: remove cc-option-yn test for -mtune= arc: replace cc-option-yn uses with cc-option s390: replace cc-option-yn uses with cc-option ia64: move core-y in arch/ia64/Makefile to arch/ia64/Kbuild sparc: move the install rule to arch/sparc/Makefile security: remove unneeded subdir-$(CONFIG_...) kbuild: sh: remove unused install script kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y kbuild: Switch to 'f' variants of integrated assembler flag kbuild: Shuffle blank line to improve comment meaning ...