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-rw-r--r--arch/x86/mm/pat.c83
1 files changed, 83 insertions, 0 deletions
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index f049b1d6ebd..aceb6c7c6db 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -211,6 +211,75 @@ static struct memtype *cached_entry;
static u64 cached_start;
/*
+ * RED-PEN: TODO: Add PageReserved() check as well here,
+ * once we add SetPageReserved() to all the drivers using
+ * set_memory_* or set_pages_*.
+ *
+ * This will help prevent accidentally freeing pages
+ * before setting the attribute back to WB.
+ */
+
+/*
+ * For RAM pages, mark the pages as non WB memory type using
+ * PageNonWB (PG_arch_1). We allow only one set_memory_uc() or
+ * set_memory_wc() on a RAM page at a time before marking it as WB again.
+ * This is ok, because only one driver will be owning the page and
+ * doing set_memory_*() calls.
+ *
+ * For now, we use PageNonWB to track that the RAM page is being mapped
+ * as non WB. In future, we will have to use one more flag
+ * (or some other mechanism in page_struct) to distinguish between
+ * UC and WC mapping.
+ */
+static int reserve_ram_pages_type(u64 start, u64 end, unsigned long req_type,
+ unsigned long *new_type)
+{
+ struct page *page;
+ u64 pfn, end_pfn;
+
+ for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
+ page = pfn_to_page(pfn);
+ if (page_mapped(page) || PageNonWB(page))
+ goto out;
+
+ SetPageNonWB(page);
+ }
+ return 0;
+
+out:
+ end_pfn = pfn;
+ for (pfn = (start >> PAGE_SHIFT); pfn < end_pfn; ++pfn) {
+ page = pfn_to_page(pfn);
+ ClearPageNonWB(page);
+ }
+
+ return -EINVAL;
+}
+
+static int free_ram_pages_type(u64 start, u64 end)
+{
+ struct page *page;
+ u64 pfn, end_pfn;
+
+ for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
+ page = pfn_to_page(pfn);
+ if (page_mapped(page) || !PageNonWB(page))
+ goto out;
+
+ ClearPageNonWB(page);
+ }
+ return 0;
+
+out:
+ end_pfn = pfn;
+ for (pfn = (start >> PAGE_SHIFT); pfn < end_pfn; ++pfn) {
+ page = pfn_to_page(pfn);
+ SetPageNonWB(page);
+ }
+ return -EINVAL;
+}
+
+/*
* req_type typically has one of the:
* - _PAGE_CACHE_WB
* - _PAGE_CACHE_WC
@@ -232,6 +301,7 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
unsigned long actual_type;
struct list_head *where;
int err = 0;
+ int is_range_ram;
BUG_ON(start >= end); /* end is exclusive */
@@ -270,6 +340,12 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
actual_type = pat_x_mtrr_type(start, end,
req_type & _PAGE_CACHE_MASK);
+ is_range_ram = pagerange_is_ram(start, end);
+ if (is_range_ram == 1)
+ return reserve_ram_pages_type(start, end, req_type, new_type);
+ else if (is_range_ram < 0)
+ return -EINVAL;
+
new = kmalloc(sizeof(struct memtype), GFP_KERNEL);
if (!new)
return -ENOMEM;
@@ -358,6 +434,7 @@ int free_memtype(u64 start, u64 end)
{
struct memtype *entry;
int err = -EINVAL;
+ int is_range_ram;
if (!pat_enabled)
return 0;
@@ -366,6 +443,12 @@ int free_memtype(u64 start, u64 end)
if (is_ISA_range(start, end - 1))
return 0;
+ is_range_ram = pagerange_is_ram(start, end);
+ if (is_range_ram == 1)
+ return free_ram_pages_type(start, end);
+ else if (is_range_ram < 0)
+ return -EINVAL;
+
spin_lock(&memtype_lock);
list_for_each_entry(entry, &memtype_list, nd) {
if (entry->start == start && entry->end == end) {