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 <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Tony Luck <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- arch/x86/mm/pat.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 1555bd7d3449..6788ffa990f8 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 it 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; _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
