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Revision f80872e2

IDf80872e21c07edd06eb343eeeefc8af404b518a6

Added by David Gibson about 11 years ago

mmu-hash64: Implement Virtual Page Class Key Protection

Version 2.06 of the Power architecture describes an additional page
protection mechanism. Each virtual page has a "class" (0-31) recorded in
the PTE. The AMR register contains bits which can prohibit reads and/or
writes on a class by class basis. Interestingly, the AMR is userspace
readable and writable, however user mode writes are masked by the contents
of the UAMOR which is privileged.

This patch implements this protection mechanism, along with the AMR and
UAMOR SPRs. The architecture also specifies a hypervisor-privileged AMOR
register which masks user and supervisor writes to the AMR and UAMOR. We
leave this out for now, since we don't at present model hypervisor mode
correctly in any case.

Signed-off-by: David Gibson <>
[agraf: fix 32-bit hosts]
Signed-off-by: Alexander Graf <>

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