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Message-Id: <1414450545-14028-7-git-send-email-toshi.kani@hp.com>
Date: Mon, 27 Oct 2014 16:55:44 -0600
From: Toshi Kani <toshi.kani@...com>
To: hpa@...or.com, tglx@...utronix.de, mingo@...hat.com,
akpm@...ux-foundation.org, arnd@...db.de
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, jgross@...e.com,
stefan.bader@...onical.com, luto@...capital.net, hmh@....eng.br,
yigal@...xistor.com, konrad.wilk@...cle.com,
Toshi Kani <toshi.kani@...com>
Subject: [PATCH v4 6/7] x86, mm, asm: Add WT support to set_page_memtype()
As set_memory_wb() calls set_page_memtype() with -1, _PGMT_DEFAULT is
solely used for tracking the WB type. _PGMT_WB is defined but unused.
Hence, this patch renames _PGMT_DEFAULT to _PGMT_WB to clarify its
usage, and releases the slot used by _PGMT_WB before. As a result,
set_memory_wb() is changed to call set_page_memtype() with _PGMT_WB,
and set_page_memtype() handles any undefined type as a bug.
This patch then defines _PGMT_WT to the released slot. This enables
set_page_memtype() to track the WT type.
Signed-off-by: Toshi Kani <toshi.kani@...com>
---
arch/x86/include/asm/cacheflush.h | 28 ++++++++++++++--------------
arch/x86/mm/pat.c | 20 ++++++--------------
2 files changed, 20 insertions(+), 28 deletions(-)
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index c912680..a561171 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -7,18 +7,18 @@
#ifdef CONFIG_X86_PAT
/*
- * X86 PAT uses page flags WC and Uncached together to keep track of
- * memory type of pages that have backing page struct. X86 PAT supports 3
- * different memory types, _PAGE_CACHE_MODE_WB, _PAGE_CACHE_MODE_WC and
- * _PAGE_CACHE_MODE_UC_MINUS and fourth state where page's memory type has not
- * been changed from its default (value of -1 used to denote this).
+ * X86 PAT uses page flags arch_1 and uncached together to keep track of
+ * memory type of pages that have backing page struct. X86 PAT supports 4
+ * different memory types, _PAGE_CACHE_MODE_WT, _PAGE_CACHE_MODE_WC,
+ * _PAGE_CACHE_MODE_UC_MINUS and _PAGE_CACHE_MODE_WB where page's memory
+ * type has not been changed from its default.
* Note we do not support _PAGE_CACHE_MODE_UC here.
*/
-#define _PGMT_DEFAULT 0
+#define _PGMT_WB 0 /* default */
#define _PGMT_WC (1UL << PG_arch_1)
#define _PGMT_UC_MINUS (1UL << PG_uncached)
-#define _PGMT_WB (1UL << PG_uncached | 1UL << PG_arch_1)
+#define _PGMT_WT (1UL << PG_uncached | 1UL << PG_arch_1)
#define _PGMT_MASK (1UL << PG_uncached | 1UL << PG_arch_1)
#define _PGMT_CLEAR_MASK (~_PGMT_MASK)
@@ -26,14 +26,14 @@ static inline enum page_cache_mode get_page_memtype(struct page *pg)
{
unsigned long pg_flags = pg->flags & _PGMT_MASK;
- if (pg_flags == _PGMT_DEFAULT)
- return -1;
+ if (pg_flags == _PGMT_WB)
+ return _PAGE_CACHE_MODE_WB;
else if (pg_flags == _PGMT_WC)
return _PAGE_CACHE_MODE_WC;
else if (pg_flags == _PGMT_UC_MINUS)
return _PAGE_CACHE_MODE_UC_MINUS;
else
- return _PAGE_CACHE_MODE_WB;
+ return _PAGE_CACHE_MODE_WT;
}
static inline void set_page_memtype(struct page *pg,
@@ -50,16 +50,16 @@ static inline void set_page_memtype(struct page *pg,
case _PAGE_CACHE_MODE_UC_MINUS:
memtype_flags = _PGMT_UC_MINUS;
break;
+ case _PAGE_CACHE_MODE_WT:
+ memtype_flags = _PGMT_WT;
+ break;
case _PAGE_CACHE_MODE_WB:
memtype_flags = _PGMT_WB;
break;
- case _PAGE_CACHE_MODE_WT:
case _PAGE_CACHE_MODE_WP:
+ default:
pr_err("set_page_memtype: unsupported cachemode %d\n", memtype);
BUG();
- default:
- memtype_flags = _PGMT_DEFAULT;
- break;
}
do {
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 648b885..4f61483 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -311,8 +311,8 @@ static int pat_pagerange_is_ram(resource_size_t start, resource_size_t end)
/*
* For RAM pages, we use page flags to mark the pages with appropriate type.
- * The page flags are currently limited to three types, WB, WC and UC. Hence,
- * any request to WT or WP will fail with -EINVAL.
+ * The page flags are limited to four memtypes, WB (default), WC, WT and UC.
+ * A new memtype can only be set to the default memtype WB.
* Here we do two pass:
* - Find the memtype of all the pages in the range, look for any conflicts
* - In case of no conflicts, set the new memtype for pages in the range
@@ -324,8 +324,7 @@ static int reserve_ram_pages_type(u64 start, u64 end,
struct page *page;
u64 pfn;
- if ((req_type == _PAGE_CACHE_MODE_WT) ||
- (req_type == _PAGE_CACHE_MODE_WP)) {
+ if (req_type == _PAGE_CACHE_MODE_WP) {
if (new_type)
*new_type = _PAGE_CACHE_MODE_UC_MINUS;
return -EINVAL;
@@ -342,7 +341,7 @@ static int reserve_ram_pages_type(u64 start, u64 end,
page = pfn_to_page(pfn);
type = get_page_memtype(page);
- if (type != -1) {
+ if (type != _PAGE_CACHE_MODE_WB) {
pr_info("reserve_ram_pages_type failed [mem %#010Lx-%#010Lx], track 0x%x, req 0x%x\n",
start, end - 1, type, req_type);
if (new_type)
@@ -369,7 +368,7 @@ static int free_ram_pages_type(u64 start, u64 end)
for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
page = pfn_to_page(pfn);
- set_page_memtype(page, -1);
+ set_page_memtype(page, _PAGE_CACHE_MODE_WB);
}
return 0;
}
@@ -498,7 +497,7 @@ int free_memtype(u64 start, u64 end)
* @paddr: physical address of which memory type needs to be looked up
*
* Returns _PAGE_CACHE_MODE_WB, _PAGE_CACHE_MODE_WC, _PAGE_CACHE_MODE_UC_MINUS
- * or _PAGE_CACHE_MODE_UC
+ * or _PAGE_CACHE_MODE_WT.
*/
static enum page_cache_mode lookup_memtype(u64 paddr)
{
@@ -512,13 +511,6 @@ static enum page_cache_mode lookup_memtype(u64 paddr)
struct page *page;
page = pfn_to_page(paddr >> PAGE_SHIFT);
rettype = get_page_memtype(page);
- /*
- * -1 from get_page_memtype() implies RAM page is in its
- * default state and not reserved, and hence of type WB
- */
- if (rettype == -1)
- rettype = _PAGE_CACHE_MODE_WB;
-
return rettype;
}
--
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