linux.git/arch/powerpc/kernel/security.c, branch v5.14

powerpc/security: Add a security feature for STF barrier

2021-06-21T11:13:19+00:00

Rather than tying this mitigation to RFI L1D flush requirement, add a
new bit for it.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210503130243.891868-3-npiggin@gmail.com

Merge branch 'topic/ppc-kvm' into next

2021-06-17T06:51:38+00:00

Merge some powerpc KVM patches from our topic branch.

In particular this brings in Nick's big series rewriting parts of the
guest entry/exit path in C.

Conflicts:
	arch/powerpc/kernel/security.c
	arch/powerpc/kvm/book3s_hv_rmhandlers.S

powerpc/security: Use PPC_RAW_BLR() and PPC_RAW_NOP()

2021-06-15T14:16:48+00:00

On the road to remove all use of PPC_INST_xxx, replace
PPC_INST_BLR by PPC_RAW_BLR(). Same for PPC_INST_NOP.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/c04f88d0e53d2122fbbe92226892a01ebc668b6a.1621506159.git.christophe.leroy@csgroup.eu

KVM: PPC: Book3S HV P9: Implement the rest of the P9 path in C

2021-06-10T12:12:13+00:00

Almost all logic is moved to C, by introducing a new in_guest mode for
the P9 path that branches very early in the KVM interrupt handler to P9
exit code.

The main P9 entry and exit assembly is now only about 160 lines of low
level stack setup and register save/restore, plus a bad-interrupt
handler.

There are two motivations for this, the first is just make the code more
maintainable being in C. The second is to reduce the amount of code
running in a special KVM mode, "realmode". In quotes because with radix
it is no longer necessarily real-mode in the MMU, but it still has to be
treated specially because it may be in real-mode, and has various
important registers like PID, DEC, TB, etc set to guest. This is hostile
to the rest of Linux and can't use arbitrary kernel functionality or be
instrumented well.

This initial patch is a reasonably faithful conversion of the asm code,
but it does lack any loop to return quickly back into the guest without
switching out of realmode in the case of unimportant or easily handled
interrupts. As explained in previous changes, handling HV interrupts
very quickly in this low level realmode is not so important for P9
performance, and are important to avoid for security, observability,
debugability reasons.

Signed-off-by: Nicholas Piggin 
Reviewed-by: Alexey Kardashevskiy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210528090752.3542186-15-npiggin@gmail.com

powerpc/security: Make symbol 'stf_barrier' static

2021-04-14T13:04:13+00:00

The sparse tool complains as follows:

arch/powerpc/kernel/security.c:253:6: warning:
 symbol 'stf_barrier' was not declared. Should it be static?

This symbol is not used outside of security.c, so this commit marks it
static.

Signed-off-by: Li Huafei 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210408033951.28369-1-lihuafei1@huawei.com

powerpc/64: Move security code into security.c

2021-04-08T11:17:43+00:00

When the original spectre/meltdown mitigations were merged we put them
in setup_64.c for lack of a better place.

Since then we created security.c for some of the other mitigation
related code. But it should all be in there.

This sort of code movement can cause trouble for backports, but
hopefully this code is relatively stable these days (famous last words).

Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210326101201.1973552-1-mpe@ellerman.id.au

powerpc/security: Fix link stack flush instruction

2020-10-08T01:50:52+00:00

The inline execution path for the hardware assisted branch flush
instruction failed to set CTR to the correct value before bcctr,
causing a crash when the feature is enabled.

Fixes: 4d24e21cc694 ("powerpc/security: Allow for processors that flush the link stack using the special bcctr")
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20201007080605.64423-1-npiggin@gmail.com

powerpc/security: Allow for processors that flush the link stack using the special bcctr

2020-07-16T03:12:32+00:00

If both count cache and link stack are to be flushed, and can be flushed
with the special bcctr, patch that in directly to the flush/branch nop
site.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200609070610.846703-7-npiggin@gmail.com

powerpc/security: split branch cache flush toggle from code patching

2020-07-16T03:12:32+00:00

Branch cache flushing code patching has inter-dependencies on both the
link stack and the count cache flushing state.

To make the code clearer and to separate the link stack and count
cache handling, split the "toggle" (setting up variables and printing
enable/disable) from the code patching.

Signed-off-by: Nicholas Piggin 
[mpe: Always print something, even if the flush is disabled]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200609070610.846703-5-npiggin@gmail.com

powerpc/security: make display of branch cache flush more consistent

2020-07-16T03:12:31+00:00

Make the count-cache and link-stack messages look the same

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200609070610.846703-4-npiggin@gmail.com