x86/hibernate/64: Mask off CR3's PCID bits in the saved CR3
Jiri reported a resume-from-hibernation failure triggered by PCID. The root cause appears to be rather odd. The hibernation asm restores a CR3 value that comes from the image header. If the image kernel has PCID on, it's entirely reasonable for this CR3 value to have one of the low 12 bits set. The restore code restores it with CR4.PCIDE=0, which means that those low 12 bits are accepted by the CPU but are either ignored or interpreted as a caching mode. This is odd, but still works. We blow up later when the image kernel restores CR4, though, since changing CR4.PCIDE with CR3[11:0] != 0 is illegal. Boom! FWIW, it's entirely unclear to me what's supposed to happen if a PAE kernel restores a non-PAE image or vice versa. Ditto for LA57. Reported-by: NJiri Kosina <jikos@kernel.org> Tested-by: NJiri Kosina <jkosina@suse.cz> Signed-off-by: NAndy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 660da7c9 ("x86/mm: Enable CR4.PCIDE on supported systems") Link: http://lkml.kernel.org/r/18ca57090651a6341e97083883f9e814c4f14684.1504847163.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
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