[PATCH 12/20] x86/mm: Add set_memory_wt() for Write-Through type

Borislav Petkov
2015-06-04T17:01:40Z

From: Toshi Kani <toshi.kani@hp.com>

Now that reserve_ram_pages_type() accepts the WT type, add
set_memory_wt(), set_memory_array_wt() and set_pages_array_wt() in order
to be able to set memory to Write-Through page cache mode.

Also, extend ioremap_change_attr() to accept the WT type.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: arnd@arndb.de
Cc: Elliott@hp.com
Cc: hch@lst.de
Cc: hmh@hmh.eng.br
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: jgross@suse.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: linux-nvdimm@lists.01.org
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: stefan.bader@canonical.com
Cc: x86-ml <x86@kernel.org>
Cc: yigal@plexistor.com
Link: http://lkml.kernel.org/r/1433187393-22688-10-git-send-email-toshi.kani@hp.com
Signed-off-by: Borislav Petkov <bp@suse.de>
---
Documentation/x86/pat.txt | 9 ++++--
arch/x86/include/asm/cacheflush.h | 6 +++-
arch/x86/mm/ioremap.c | 3 ++
arch/x86/mm/pageattr.c | 62 +++++++++++++++++++++++++++++++--------
4 files changed, 63 insertions(+), 17 deletions(-)

diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt
index db0de6cfc351..54944c71b819 100644
--- a/Documentation/x86/pat.txt
+++ b/Documentation/x86/pat.txt
@@ -48,6 +48,9 @@ set_memory_uc | UC- | -- | -- |
set_memory_wc | WC | -- | -- |
set_memory_wb | | | |
| | | |
+set_memory_wt | WT | -- | -- |
+ set_memory_wb | | | |
+ | | | |
pci sysfs resource | -- | -- | UC- |
| | | |
pci sysfs resource_wc | -- | -- | WC |
@@ -150,8 +153,8 @@ can be more restrictive, in case of any existing aliasing for that address.
For example: If there is an existing uncached mapping, a new ioremap_wc can
return uncached mapping in place of write-combine requested.

-set_memory_[uc|wc] and set_memory_wb should be used in pairs, where driver will
-first make a region uc or wc and switch it back to wb after use.
+set_memory_[uc|wc|wt] and set_memory_wb should be used in pairs, where driver
+will first make a region uc, wc or wt and switch it back to wb after use.

Over time writes to /proc/mtrr will be deprecated in favor of using PAT based
interfaces. Users writing to /proc/mtrr are suggested to use above interfaces.
@@ -159,7 +162,7 @@ interfaces. Users writing to /proc/mtrr are suggested to use above interfaces.
Drivers should use ioremap_[uc|wc] to access PCI BARs with [uc|wc] access
types.

-Drivers should use set_memory_[uc|wc] to set access type for RAM ranges.
+Drivers should use set_memory_[uc|wc|wt] to set access type for RAM ranges.

PAT debugging
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index 47c8e32f621a..b6f7457d12e4 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -8,7 +8,7 @@
/*
* The set_memory_* API can be used to change various attributes of a virtual
* address range. The attributes include:
- * Cachability : UnCached, WriteCombining, WriteBack
+ * Cachability : UnCached, WriteCombining, WriteThrough, WriteBack
* Executability : eXeutable, NoteXecutable
* Read/Write : ReadOnly, ReadWrite
* Presence : NotPresent
@@ -35,9 +35,11 @@

int _set_memory_uc(unsigned long addr, int numpages);
int _set_memory_wc(unsigned long addr, int numpages);
+int _set_memory_wt(unsigned long addr, int numpages);
int _set_memory_wb(unsigned long addr, int numpages);
int set_memory_uc(unsigned long addr, int numpages);
int set_memory_wc(unsigned long addr, int numpages);
+int set_memory_wt(unsigned long addr, int numpages);
int set_memory_wb(unsigned long addr, int numpages);
int set_memory_x(unsigned long addr, int numpages);
int set_memory_nx(unsigned long addr, int numpages);
@@ -48,10 +50,12 @@ int set_memory_4k(unsigned long addr, int numpages);

int set_memory_array_uc(unsigned long *addr, int addrinarray);
int set_memory_array_wc(unsigned long *addr, int addrinarray);
+int set_memory_array_wt(unsigned long *addr, int addrinarray);
int set_memory_array_wb(unsigned long *addr, int addrinarray);

int set_pages_array_uc(struct page **pages, int addrinarray);
int set_pages_array_wc(struct page **pages, int addrinarray);
+int set_pages_array_wt(struct page **pages, int addrinarray);
int set_pages_array_wb(struct page **pages, int addrinarray);

/*
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 07cd46a8f30a..8405c0c6a535 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -42,6 +42,9 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size,
case _PAGE_CACHE_MODE_WC:
err = _set_memory_wc(vaddr, nrpages);
break;
+ case _PAGE_CACHE_MODE_WT:
+ err = _set_memory_wt(vaddr, nrpages);
+ break;
case _PAGE_CACHE_MODE_WB:
err = _set_memory_wb(vaddr, nrpages);
break;
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 94aae76a5e06..d908f197c58f 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1502,12 +1502,10 @@ EXPORT_SYMBOL(set_memory_uc);
static int _set_memory_array(unsigned long *addr, int addrinarray,
enum page_cache_mode new_type)
{
+ enum page_cache_mode set_type;
int i, j;
int ret;

- /*
- * for now UC MINUS. see comments in ioremap_nocache()
- */
for (i = 0; i < addrinarray; i++) {
ret = reserve_memtype(__pa(addr[i]), __pa(addr[i]) + PAGE_SIZE,
new_type, NULL);
@@ -1515,9 +1513,12 @@ static int _set_memory_array(unsigned long *addr, int addrinarray,
goto out_free;
}

+ /* If WC, set to UC- first and then WC */
+ set_type = (new_type == _PAGE_CACHE_MODE_WC) ?
+ _PAGE_CACHE_MODE_UC_MINUS : new_type;
+
ret = change_page_attr_set(addr, addrinarray,
- cachemode2pgprot(_PAGE_CACHE_MODE_UC_MINUS),
- 1);
+ cachemode2pgprot(set_type), 1);

if (!ret && new_type == _PAGE_CACHE_MODE_WC)
ret = change_page_attr_set_clr(addr, addrinarray,
@@ -1549,6 +1550,12 @@ int set_memory_array_wc(unsigned long *addr, int addrinarray)
}
EXPORT_SYMBOL(set_memory_array_wc);

+int set_memory_array_wt(unsigned long *addr, int addrinarray)
+{
+ return _set_memory_array(addr, addrinarray, _PAGE_CACHE_MODE_WT);
+}
+EXPORT_SYMBOL_GPL(set_memory_array_wt);
+
int _set_memory_wc(unsigned long addr, int numpages)
{
int ret;
@@ -1574,21 +1581,39 @@ int set_memory_wc(unsigned long addr, int numpages)
ret = reserve_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE,
_PAGE_CACHE_MODE_WC, NULL);
if (ret)
- goto out_err;
+ return ret;

ret = _set_memory_wc(addr, numpages);
if (ret)
- goto out_free;
+ free_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);

- return 0;
-
-out_free:
- free_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);
-out_err:
return ret;
}
EXPORT_SYMBOL(set_memory_wc);

+int _set_memory_wt(unsigned long addr, int numpages)
+{
+ return change_page_attr_set(&addr, numpages,
+ cachemode2pgprot(_PAGE_CACHE_MODE_WT), 0);
+}
+
+int set_memory_wt(unsigned long addr, int numpages)
+{
+ int ret;
+
+ ret = reserve_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE,
+ _PAGE_CACHE_MODE_WT, NULL);
+ if (ret)
+ return ret;
+
+ ret = _set_memory_wt(addr, numpages);
+ if (ret)
+ free_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(set_memory_wt);
+
int _set_memory_wb(unsigned long addr, int numpages)
{
/* WB cache mode is hard wired to all cache attribute bits being 0 */
@@ -1679,6 +1704,7 @@ static int _set_pages_array(struct page **pages, int addrinarray,
{
unsigned long start;
unsigned long end;
+ enum page_cache_mode set_type;
int i;
int free_idx;
int ret;
@@ -1692,8 +1718,12 @@ static int _set_pages_array(struct page **pages, int addrinarray,
goto err_out;
}

+ /* If WC, set to UC- first and then WC */
+ set_type = (new_type == _PAGE_CACHE_MODE_WC) ?
+ _PAGE_CACHE_MODE_UC_MINUS : new_type;
+
ret = cpa_set_pages_array(pages, addrinarray,
- cachemode2pgprot(_PAGE_CACHE_MODE_UC_MINUS));
+ cachemode2pgprot(set_type));
if (!ret && new_type == _PAGE_CACHE_MODE_WC)
ret = change_page_attr_set_clr(NULL, addrinarray,
cachemode2pgprot(
@@ -1727,6 +1757,12 @@ int set_pages_array_wc(struct page **pages, int addrinarray)
}
EXPORT_SYMBOL(set_pages_array_wc);

+int set_pages_array_wt(struct page **pages, int addrinarray)
+{
+ return _set_pages_array(pages, addrinarray, _PAGE_CACHE_MODE_WT);
+}
+EXPORT_SYMBOL_GPL(set_pages_array_wt);
+
int set_pages_wb(struct page *page, int numpages)
{
unsigned long addr = (unsigned long)page_address(page);
--
2.3.5