[26.04_linux-nvidia-bos] vfio/cxl: include <linux/bitfield.h> for FIELD_GET - #544
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vfio_cxl_core.c uses FIELD_GET() to decode the CXL DVSEC capability register but does not include <linux/bitfield.h>. It has only compiled because on arm64 the macro is pulled in transitively: linux/slab.h -> linux/cache.h -> arch/arm64/include/asm/cache.h -> asm/cputype.h -> asm/sysreg.h, and arm64's asm/sysreg.h includes <linux/bitfield.h>. The nvidia-bos kernel is also built for amd64, where that arm64-only header chain does not exist. There FIELD_GET is undefined and the build fails with "implicit declaration of function 'FIELD_GET'". Include <linux/bitfield.h> directly so the file no longer relies on any architecture's transitive include graph. This fix is only needed for commit 3570209 ("NVIDIA: VR: SAUCE: vfio/cxl: Virtualize CXL DVSEC config writes"), which is derived from the v2 posting of the CXL VFIO Type-2 passthrough series. Version 3 and later of that upstream series already include <linux/bitfield.h> in this file directly, so once the tree moves to v3+ this change becomes redundant and drops out naturally. Fixes: 3570209 ("NVIDIA: VR: SAUCE: vfio/cxl: Virtualize CXL DVSEC config writes") Signed-off-by: Jiandi An <jan@nvidia.com>
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PR Validation ReportPatchscan ✅ No Missing FixesAll cherry-picked commits checked — no missing upstream fixes found. PR Lint ✅ All checks passedDetailsChecking 1 commits... Cherry-pick digest: ┌──────────────┬──────────────────────────────────────────────────────────────────┬────────────┬─────────┬───────────────────────────┐ │ Local │ Referenced upstream / Patch subject │ Patch-ID │ Subject │ SoB chain │ ├──────────────┼──────────────────────────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤ │ 44a2c0cc2bf4 │ [SAUCE] vfio/cxl: include <linux/bitfield.h> for field_get │ N/A │ N/A │ jan │ └──────────────┴──────────────────────────────────────────────────────────────────┴────────────┴─────────┴───────────────────────────┘ Lint: all checks passed. |
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BaseOS Kernel ReviewSummaryNo issues found across the reviewed commits. Findings: no problems found Latest watcher review: open review Generated test plan: open test plan Kernel deb build: successful (download debs, 4 files) Head: This comment is maintained by nv-pr-bot. It is updated when the GitHub watcher publishes a newer review. |
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Summary
Fixes an amd64 build break in the merged CXL VFIO Type-2 passthrough v2 series:
drivers/vfio/pci/cxl/vfio_cxl_core.cusesFIELD_GET()without including<linux/bitfield.h>. Adds the missing include.The failure
On amd64 (
resolute:linux-nvidia-bos), the build fails with:Root cause
vfio_cxl_core.ccallsFIELD_GET()(to decode the CXL DVSEC capabilityregister) but never includes
<linux/bitfield.h>, where that macro is defined.It compiled only because of an architecture-dependent transitive include:
<linux/bitfield.h>is pulled in indirectly vialinux/slab.h -> linux/cache.h -> arch/arm64/include/asm/cache.h -> asm/cputype.h -> asm/sysreg.h, and arm64'sasm/sysreg.hincludes<linux/bitfield.h>.FIELD_GETis undefined and the build fails.
The nvidia-bos kernel is built for both amd64 and arm64
(
CONFIG_VFIO_CXL_CORE=yon both), so the file must not rely on any onearchitecture's transitive include graph.
Fix
Add
#include <linux/bitfield.h>directly tovfio_cxl_core.c(include-what-you-use), making the file architecture-independent.
Scope
series (commit
3570209d539a). v3 and later of that upstream seriesalready include
<linux/bitfield.h>in this file directly, so the changebecomes redundant and drops out naturally once the tree moves to v3+.
Fixes: 3570209 ("NVIDIA: VR: SAUCE: vfio/cxl: Virtualize CXL DVSEC config writes")
LP: https://bugs.launchpad.net/ubuntu/+source/linux-nvidia-bos/+bug/2163376