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Subject[RFC PATCH 10/11] x86, xen: Cleanup PWT/PCD bit manipulation in Xen
Date
This patch cleans up the PWT & PCD bit manipulation for the kernel
memory types in Xen, and uses _PAGE_CACHE_<type> macros, instead.
This keeps the Xen code independent from the PAT slot assignment.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---
arch/x86/xen/enlighten.c | 2 +-
arch/x86/xen/mmu.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index ffb101e..1917bef 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1557,7 +1557,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
#if 0
if (!xen_initial_domain())
#endif
- __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
+ __supported_pte_mask &= ~_PAGE_CACHE_MASK;

__supported_pte_mask |= _PAGE_IOMAP;

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index e8a1201..8ef154a 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -438,7 +438,7 @@ __visible pteval_t xen_pte_val(pte_t pte)
/* If this is a WC pte, convert back from Xen WC to Linux WC */
if ((pteval & (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)) == _PAGE_PAT) {
WARN_ON(!pat_enabled);
- pteval = (pteval & ~_PAGE_PAT) | _PAGE_PWT;
+ pteval = (pteval & ~_PAGE_PAT) | _PAGE_CACHE_WC;
}
#endif
if (xen_initial_domain() && (pteval & _PAGE_IOMAP))
@@ -465,11 +465,11 @@ PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val);
* 0 WB WB WB
* 1 PWT WC WT WT
* 2 PCD UC- UC- UC-
- * 3 PCD PWT UC UC UC
+ * 3 PCD PWT WT UC UC
* 4 PAT WB WC WB
* 5 PAT PWT WC WP WT
* 6 PAT PCD UC- rsv UC-
- * 7 PAT PCD PWT UC rsv UC
+ * 7 PAT PCD PWT WT rsv UC
*/

void xen_set_pat(u64 pat)
@@ -492,7 +492,7 @@ __visible pte_t xen_make_pte(pteval_t pte)
* but we could see hugetlbfs mappings, I think.).
*/
if (pat_enabled && !WARN_ON(pte & _PAGE_PAT)) {
- if ((pte & (_PAGE_PCD | _PAGE_PWT)) == _PAGE_PWT)
+ if ((pte & _PAGE_CACHE_MASK) == _PAGE_CACHE_WC)
pte = (pte & ~(_PAGE_PCD | _PAGE_PWT)) | _PAGE_PAT;
}
#endif

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