From 510ee090abc3dbc862bd35f5f3d8b7284a9117b4 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 13 Jul 2018 21:50:27 -0700 Subject: x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses In preparation for using set_memory_uc() instead set_memory_np() for isolating poison from speculation, teach the memtype code to sanitize physical addresses vs __PHYSICAL_MASK. The motivation for using set_memory_uc() for this case is to allow ongoing access to persistent memory pages via the pmem-driver + memcpy_mcsafe() until the poison is repaired. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Tony Luck Cc: Borislav Petkov Cc: Cc: Signed-off-by: Dan Williams Acked-by: Ingo Molnar Signed-off-by: Dave Jiang --- arch/x86/mm/pat.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 1555bd7d3449..3d0c83ef6aab 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -512,6 +512,17 @@ static int free_ram_pages_type(u64 start, u64 end) return 0; } +static u64 sanitize_phys(u64 address) +{ + /* + * When changing the memtype for pages containing poison allow + * for a "decoy" virtual address (bit 63 clear) passed to + * set_memory_X(). __pa() on a "decoy" address results in a + * physical address with bit 63 set. + */ + return address & __PHYSICAL_MASK; +} + /* * req_type typically has one of the: * - _PAGE_CACHE_MODE_WB @@ -533,6 +544,8 @@ int reserve_memtype(u64 start, u64 end, enum page_cache_mode req_type, int is_range_ram; int err = 0; + start = sanitize_phys(start); + end = sanitize_phys(end); BUG_ON(start >= end); /* end is exclusive */ if (!pat_enabled()) { @@ -609,6 +622,9 @@ int free_memtype(u64 start, u64 end) if (!pat_enabled()) return 0; + start = sanitize_phys(start); + end = sanitize_phys(end); + /* Low ISA region is always mapped WB. No need to track */ if (x86_platform.is_untracked_pat_range(start, end)) return 0; -- cgit v1.2.3