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x86: PAT: make pat_x_mtrr_type() more readable
Clean up over-complications in pat_x_mtrr_type(). And if reserve_memtype() ignores stray req_type bits when pat_enabled, it's better to mask them off when not also. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -159,47 +159,31 @@ static DEFINE_SPINLOCK(memtype_lock); /* protects memtype list */
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* The intersection is based on "Effective Memory Type" tables in IA-32
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* SDM vol 3a
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*/
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static int pat_x_mtrr_type(u64 start, u64 end, unsigned long prot,
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unsigned long *ret_prot)
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static unsigned long pat_x_mtrr_type(u64 start, u64 end, unsigned long req_type)
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{
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unsigned long pat_type;
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u8 mtrr_type;
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pat_type = prot & _PAGE_CACHE_MASK;
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prot &= (~_PAGE_CACHE_MASK);
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/*
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* We return the PAT request directly for types where PAT takes
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* precedence with respect to MTRR and for UC_MINUS.
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* Consistency checks with other PAT requests is done later
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* while going through memtype list.
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*/
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if (pat_type == _PAGE_CACHE_WC) {
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*ret_prot = prot | _PAGE_CACHE_WC;
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return 0;
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} else if (pat_type == _PAGE_CACHE_UC_MINUS) {
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*ret_prot = prot | _PAGE_CACHE_UC_MINUS;
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return 0;
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} else if (pat_type == _PAGE_CACHE_UC) {
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*ret_prot = prot | _PAGE_CACHE_UC;
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return 0;
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}
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if (req_type == _PAGE_CACHE_WC ||
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req_type == _PAGE_CACHE_UC_MINUS ||
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req_type == _PAGE_CACHE_UC)
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return req_type;
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/*
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* Look for MTRR hint to get the effective type in case where PAT
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* request is for WB.
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*/
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mtrr_type = mtrr_type_lookup(start, end);
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if (mtrr_type == MTRR_TYPE_UNCACHABLE) {
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*ret_prot = prot | _PAGE_CACHE_UC;
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} else if (mtrr_type == MTRR_TYPE_WRCOMB) {
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*ret_prot = prot | _PAGE_CACHE_WC;
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} else {
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*ret_prot = prot | _PAGE_CACHE_WB;
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}
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return 0;
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if (mtrr_type == MTRR_TYPE_UNCACHABLE)
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return _PAGE_CACHE_UC;
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if (mtrr_type == MTRR_TYPE_WRCOMB)
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return _PAGE_CACHE_WC;
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return _PAGE_CACHE_WB;
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}
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/*
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@ -232,7 +216,7 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
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if (req_type == -1) {
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*ret_type = _PAGE_CACHE_WB;
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} else {
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*ret_type = req_type;
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*ret_type = req_type & _PAGE_CACHE_MASK;
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}
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}
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return 0;
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@ -264,14 +248,7 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
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}
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} else {
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req_type &= _PAGE_CACHE_MASK;
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err = pat_x_mtrr_type(start, end, req_type, &actual_type);
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}
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if (err) {
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if (ret_type)
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*ret_type = actual_type;
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return -EINVAL;
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actual_type = pat_x_mtrr_type(start, end, req_type);
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}
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new_entry = kmalloc(sizeof(struct memtype), GFP_KERNEL);
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