x86/mm: Teach is_new_memtype_allowed() about Write-Through type
__ioremap_caller() calls reserve_memtype() and the passed down @new_pcm contains the actual page cache type it reserved in the success case. is_new_memtype_allowed() verifies if converting to the new page cache type is allowed when @pcm (the requested type) is different from @new_pcm. When WT is requested, the caller expects that writes are ordered and uncached. Therefore, enhance is_new_memtype_allowed() to disallow the following cases: - If the request is WT, mapping type cannot be WB - If the request is WT, mapping type cannot be WC Signed-off-by: Toshi Kani <toshi.kani@hp.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Elliott@hp.com Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: arnd@arndb.de Cc: hch@lst.de Cc: hmh@hmh.eng.br Cc: jgross@suse.com Cc: konrad.wilk@oracle.com Cc: linux-mm <linux-mm@kvack.org> Cc: linux-nvdimm@lists.01.org Cc: stefan.bader@canonical.com Cc: yigal@plexistor.com Link: http://lkml.kernel.org/r/1433436928-31903-7-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -398,11 +398,17 @@ static inline int is_new_memtype_allowed(u64 paddr, unsigned long size,
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* requested memtype:
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* requested memtype:
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* - request is uncached, return cannot be write-back
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* - request is uncached, return cannot be write-back
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* - request is write-combine, return cannot be write-back
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* - request is write-combine, return cannot be write-back
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* - request is write-through, return cannot be write-back
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* - request is write-through, return cannot be write-combine
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*/
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*/
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if ((pcm == _PAGE_CACHE_MODE_UC_MINUS &&
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if ((pcm == _PAGE_CACHE_MODE_UC_MINUS &&
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new_pcm == _PAGE_CACHE_MODE_WB) ||
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new_pcm == _PAGE_CACHE_MODE_WB) ||
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(pcm == _PAGE_CACHE_MODE_WC &&
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(pcm == _PAGE_CACHE_MODE_WC &&
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new_pcm == _PAGE_CACHE_MODE_WB)) {
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new_pcm == _PAGE_CACHE_MODE_WB) ||
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(pcm == _PAGE_CACHE_MODE_WT &&
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new_pcm == _PAGE_CACHE_MODE_WB) ||
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(pcm == _PAGE_CACHE_MODE_WT &&
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new_pcm == _PAGE_CACHE_MODE_WC)) {
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return 0;
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return 0;
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}
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}
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