| Message ID | 1431551151-19124-4-git-send-email-toshi.kani@hp.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, 13 May 2015, Toshi Kani wrote: > __ioremap_caller() calls reserve_memtype() to set new_pcm > (existing map type if any), and then calls > is_new_memtype_allowed() to verify if converting to new_pcm > is allowed when pcm (request type) is different from new_pcm. > > When WT is requested, the caller expects that writes are > ordered and uncached. Therefore, this patch changes > 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> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index fe57e7a..2562e30 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -398,11 +398,17 @@ static inline int is_new_memtype_allowed(u64 paddr, unsigned long size, * requested memtype: * - request is uncached, return cannot be write-back * - request is write-combine, return cannot be write-back + * - request is write-through, return cannot be write-back + * - request is write-through, return cannot be write-combine */ if ((pcm == _PAGE_CACHE_MODE_UC_MINUS && new_pcm == _PAGE_CACHE_MODE_WB) || (pcm == _PAGE_CACHE_MODE_WC && - new_pcm == _PAGE_CACHE_MODE_WB)) { + new_pcm == _PAGE_CACHE_MODE_WB) || + (pcm == _PAGE_CACHE_MODE_WT && + new_pcm == _PAGE_CACHE_MODE_WB) || + (pcm == _PAGE_CACHE_MODE_WT && + new_pcm == _PAGE_CACHE_MODE_WC)) { return 0; }
__ioremap_caller() calls reserve_memtype() to set new_pcm (existing map type if any), and then calls is_new_memtype_allowed() to verify if converting to new_pcm is allowed when pcm (request type) is different from new_pcm. When WT is requested, the caller expects that writes are ordered and uncached. Therefore, this patch changes 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> --- arch/x86/include/asm/pgtable.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)