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Currently memory_failure() returns zero if the error was handled. On
that result mce_unmap_kpfn() is called to zap the page out of the kernel
linear mapping to prevent speculative fetches of potentially poisoned
memory. However, in the case of dax mapped devmap pages the page may be
in active permanent use by the device driver, so it cannot be unmapped
from the kernel.
Instead of marking the page not present, marking the page UC should
be sufficient for preventing poison from being pre-fetched into the
cache. Convert mce_unmap_pfn() to set_mce_nospec() remapping the page as
UC, to hide it from speculative accesses.
Given that that persistent memory errors can be cleared by the driver,
include a facility to restore the page to cacheable operation,
clear_mce_nospec().
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]>
Acked-by: Tony Luck <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Signed-off-by: Dave Jiang <[email protected]>
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... to make these APIs more universally available.
Tested-by: Tom Lendacky <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Reviewed-by: Konrad Rzeszutek Wilk <[email protected]>
Reviewed-by: Tom Lendacky <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jon Mason <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Muli Ben-Yehuda <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Currently code that wants to use set_memory_ro() etc, needs to include
asm/set_memory.h, which doesn't exist on all arches. Some code knows it
only builds on arches which have the header, other code guards the
inclusion with an #ifdef, neither is ideal.
So create linux/set_memory.h. This always exists, so users don't need
an #ifdef just to include the header.
When CONFIG_ARCH_HAS_SET_MEMORY=y it includes asm/set_memory.h,
otherwise it provides empty non-failing implementations.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michael Ellerman <[email protected]>
Acked-by: Daniel Borkmann <[email protected]>
Acked-by: Kees Cook <[email protected]>
Acked-by: Laura Abbott <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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