x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses (510ee090) · Commits · 戴 / test

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>

arch/x86/mm/pat.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -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;

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