Commit 35a5a104 authored by Toshi Kani's avatar Toshi Kani Committed by Ingo Molnar

x86/mm/pat: Extend set_page_memtype() to support Write-Through type

As set_memory_wb() calls free_ram_pages_type(), which then calls
set_page_memtype() with -1, _PGMT_DEFAULT is used for tracking
the WB type. _PGMT_WB is defined but unused. Thus, rename
_PGMT_DEFAULT to _PGMT_WB to clarify the usage, and release the
slot used by _PGMT_WB.

Furthermore, change free_ram_pages_type() to call
set_page_memtype() with _PGMT_WB, and get_page_memtype() to
return _PAGE_CACHE_MODE_WB for _PGMT_WB.

Then, define _PGMT_WT in the freed slot. This allows
set_page_memtype() to track the WT type.
Signed-off-by: default avatarToshi Kani <toshi.kani@hp.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.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: Thomas Gleixner <tglx@linutronix.de>
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/1433436928-31903-12-git-send-email-bp@alien8.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent d1b4bfbf
......@@ -70,18 +70,22 @@ __setup("debugpat", pat_debug_setup);
#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).
* Note we do not support _PAGE_CACHE_MODE_UC here.
* 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_WB
* - _PAGE_CACHE_MODE_WC
* - _PAGE_CACHE_MODE_UC_MINUS
* - _PAGE_CACHE_MODE_WT
*
* _PAGE_CACHE_MODE_WB is the default type.
*/
#define _PGMT_DEFAULT 0
#define _PGMT_WB 0
#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)
......@@ -89,14 +93,14 @@ 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,
......@@ -113,11 +117,12 @@ 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_WB:
memtype_flags = _PGMT_WB;
case _PAGE_CACHE_MODE_WT:
memtype_flags = _PGMT_WT;
break;
case _PAGE_CACHE_MODE_WB:
default:
memtype_flags = _PGMT_DEFAULT;
memtype_flags = _PGMT_WB;
break;
}
......@@ -401,8 +406,10 @@ 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 limited to three types, WB, WC and UC-. WT and WP requests
* fail with -EINVAL, and UC gets redirected to UC-.
* The page flags are limited to four types, WB (default), WC, WT and UC-.
* WP request fails with -EINVAL, and UC gets redirected to UC-. Setting
* a new memory type is only allowed for a page mapped with the default WB
* type.
*
* Here we do two passes:
* - Find the memtype of all the pages in the range, look for any conflicts.
......@@ -415,8 +422,7 @@ 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;
......@@ -433,7 +439,7 @@ 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("x86/PAT: reserve_ram_pages_type failed [mem %#010Lx-%#010Lx], track 0x%x, req 0x%x\n",
start, end - 1, type, req_type);
if (new_type)
......@@ -460,7 +466,7 @@ 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;
}
......@@ -601,7 +607,7 @@ int free_memtype(u64 start, u64 end)
* Only to be called when PAT is enabled
*
* 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)
{
......@@ -613,16 +619,9 @@ static enum page_cache_mode lookup_memtype(u64 paddr)
if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) {
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;
page = pfn_to_page(paddr >> PAGE_SHIFT);
return get_page_memtype(page);
}
spin_lock(&memtype_lock);
......
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