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| author | Dan Williams <dan.j.williams@intel.com> | 2025-04-30 05:46:21 +0300 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2025-05-01 19:43:48 +0300 |
| commit | 1b3f2bd04d90f61e1f291b5e365b9bc4ce0ea7c7 (patch) | |
| tree | 1ea766f39a277a5b1305905e64aa187da0d7c954 /include/linux | |
| parent | eaa607deb29e0b6fd24b9adf230fbc765f342521 (diff) | |
| download | linux-1b3f2bd04d90f61e1f291b5e365b9bc4ce0ea7c7.tar.xz | |
x86/devmem: Remove duplicate range_is_allowed() definition
17 years ago, Venki suggested [1] "A future improvement would be to
avoid the range_is_allowed duplication".
The only thing preventing a common implementation is that
phys_mem_access_prot_allowed() expects the range check to exit
immediately when PAT is disabled [2]. I.e. there is no cache conflict to
manage in that case. This cleanup was noticed on the path to
considering changing range_is_allowed() policy to blanket deny /dev/mem
for private (confidential computing) memory.
Note, however that phys_mem_access_prot_allowed() has long since stopped
being relevant for managing cache-type validation due to [3], and [4].
Commit 0124cecfc85a ("x86, PAT: disable /dev/mem mmap RAM with PAT") [1]
Commit 9e41bff2708e ("x86: fix /dev/mem mmap breakage when PAT is disabled") [2]
Commit 1886297ce0c8 ("x86/mm/pat: Fix BUG_ON() in mmap_mem() on QEMU/i386") [3]
Commit 0c3c8a18361a ("x86, PAT: Remove duplicate memtype reserve in devmem mmap") [4]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/all/20250430024622.1134277-2-dan.j.williams%40intel.com
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/io.h | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/io.h b/include/linux/io.h index 6a6bc4d46d0a..0642c7ee41db 100644 --- a/include/linux/io.h +++ b/include/linux/io.h @@ -183,4 +183,25 @@ static inline void arch_io_free_memtype_wc(resource_size_t base, int devm_arch_io_reserve_memtype_wc(struct device *dev, resource_size_t start, resource_size_t size); +#ifdef CONFIG_STRICT_DEVMEM +static inline int range_is_allowed(unsigned long pfn, unsigned long size) +{ + u64 from = ((u64)pfn) << PAGE_SHIFT; + u64 to = from + size; + u64 cursor = from; + + while (cursor < to) { + if (!devmem_is_allowed(pfn)) + return 0; + cursor += PAGE_SIZE; + pfn++; + } + return 1; +} +#else +static inline int range_is_allowed(unsigned long pfn, unsigned long size) +{ + return 1; +} +#endif #endif /* _LINUX_IO_H */ |