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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 <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: <linux-edac@vger.kernel.org>
Cc: <x86@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Dan Williams 2018-07-13 21:50:27 -07:00 committed by Dave Jiang
parent 6100e34b25
commit 510ee090ab
1 changed files with 16 additions and 0 deletions
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16
arch/x86/mm/pat.c
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@ -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;