[kvm-unit-tests PATCH v2 0/4] Tests for CR0.WP=0/1 r/o write access

Mathias Krause
2023-03-31T13:57:32Z

This series adds explicit tests that verify a page fault will occur for
attempts to write to an r/o page while CR0.WP is 1 as well as access is
granted when CR0.WP is 0.

There are existing tests already, e.g. in pks.c, pku.c, smap.c or even
access.c that implicitly test this. However, they all either explicitly
(via INVLPG) or implicitly (via CR3 reload) flush the TLB before doing
the access which might lead to false positives if the access succeeded
before, e.g. because CR0.WP was 0 before.

Better to have an explicit test, especially to back up the changes of
[1] which were missing the emulator case, initially.

Please apply!

Thanks,
Mathias

[1] https://lore.kernel.org/kvm/20230322013731.102955-1-minipli@grsecurity.net/

Mathias Krause (4):
x86: Use existing CR0.WP / CR4.SMEP bit definitions
x86/access: CR0.WP toggling write to r/o data test
x86/access: Forced emulation support
x86/access: Try emulation for CR0.WP test as well

x86/access.c | 120 +++++++++++++++++++++++++++++++++++++++++++++------
x86/pks.c | 5 +--
x86/pku.c | 5 +--
3 files changed, 110 insertions(+), 20 deletions(-)

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2.39.2