diff mbox

[v11,4/12] x86, mm, pat: Change reserve_memtype() for WT

Message ID 1432940350-1802-5-git-send-email-toshi.kani@hp.com
State Superseded
Headers show

Commit Message

Toshi Kani May 29, 2015, 10:59 p.m. UTC
From: Toshi Kani <toshi.kani@hp.com>

When a RAM range is requested to reserve_memtype(), it calls
reserve_ram_pages_type() to verify the requested type.
reserve_ram_pages_type() is changed to fail WT and WP requests
with -EINVAL since set_page_memtype() is limited to handle
three types, WB, WC and UC-.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
Patch 10/12 enhances set_page_memtype() to support WT.
---
 arch/x86/mm/pat.c |   10 ++++++++++
 1 file changed, 10 insertions(+)
diff mbox

Patch

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 3d9f125..85c9fcb 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -389,6 +389,8 @@  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 limited to three types, WB, WC and UC-.
+ * WT and WP requests fail with -EINVAL, and UC gets redirected to UC-.
  * 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
@@ -400,6 +402,13 @@  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 (new_type)
+			*new_type = _PAGE_CACHE_MODE_UC_MINUS;
+		return -EINVAL;
+	}
+
 	if (req_type == _PAGE_CACHE_MODE_UC) {
 		/* We do not support strong UC */
 		WARN_ON_ONCE(1);
@@ -449,6 +458,7 @@  static int free_ram_pages_type(u64 start, u64 end)
  * - _PAGE_CACHE_MODE_WC
  * - _PAGE_CACHE_MODE_UC_MINUS
  * - _PAGE_CACHE_MODE_UC
+ * - _PAGE_CACHE_MODE_WT
  *
  * If new_type is NULL, function will return an error if it cannot reserve the
  * region with req_type. If new_type is non-NULL, function will return