Now that 40x platforms have gone, remove support
for 40x in the core of powerpc arch.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240628121201.130802-4-mpe@ellerman.id.au
PAPR will define a new ibm,pi-features bit which says that doorbells
should not be used even on architectures where they exist. This could be
because they are emulated and slower than using the interrupt controller
directly for IPIs.
Wire this bit into the pi-features parser to clear CPU_FTR_DBELL, and
ensure CPU_FTR_DBELL is not in CPU_FTRS_ALWAYS.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240207035220.339726-2-npiggin@gmail.com
Add CPU table entries for raw and architected mode. Most fields are
copied from the Power10 table entries.
CPU, MMU and user (ELF_HWCAP) features are unchanged vs P10. However
userspace can detect P11 because the AT_PLATFORM value changes to
"power11".
The logical PVR value of 0x0F000007, passed to firmware via the
ibm_arch_vec, indicates the kernel can support a P11 compatible CPU,
which means at least ISA v3.1 compliant.
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240221044623.1598642-1-mpe@ellerman.id.au
ISA 3.1B introduces the Dynamic Execution Control Register (DEXCR). It
is a per-cpu register that allows control over various CPU behaviours
including branch hint usage, indirect branch speculation, and
hashst/hashchk support.
Add some definitions and basic support for the DEXCR in the kernel.
Right now it just
* Initialises the DEXCR and HASHKEYR to a fixed value when a CPU
onlines.
* Clears them in reset_sprs().
* Detects when the NPHIE aspect is supported (the others don't get
looked at in this series, so there's no need to waste a CPU_FTR
on them).
We initialise the HASHKEYR to ensure that all cores have the same key,
so an HV enforced NPHIE + swapping cores doesn't randomly crash a
process using hash instructions. The stores to HASHKEYR are
unconditional because the ISA makes no mention of the SPR being missing
if support for doing the hashes isn't present. So all that would happen
is the HASHKEYR value gets ignored. This helps slightly if NPHIE
detection fails; e.g., we currently only detect it on pseries.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
[mpe: Use simple values for DEXCR constants]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230616034846.311705-4-bgray@linux.ibm.com
The hardware bug in POWER9 preventing use of the DAWR was fixed in
DD2.3. Set the CPU_FTR_DAWR feature bit on these newer systems to start
using it again, and update the documentation accordingly.
The CPU features for DD2.3 are currently determined by "DD2.2 or later"
logic. In adding DD2.3 as a discrete case for the first time here, I'm
carrying the quirks of DD2.2 forward to keep all behavior outside of
this DAWR change the same. This leaves the assessment and potential
removal of those quirks on DD2.3 for later.
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220503170152.23412-1-arbab@linux.ibm.com
CPU_FTRS_POWER10 is missing from the CPU_FTRS_ALWAYS mask.
Currently that doesn't cause any bug, because it is a superset of the
POWER9 mask, which the exception of CPU_FTR_TM, but POWER7 doesn't have
CPU_FTR_TM, so CPU_FTR_TM is not in the ALWAYS mask to begin with.
However for consistency, and to be robust against future changes, it
should be included in the ALWAYS mask.
Fixes: a3ea40d5c7 ("powerpc: Add POWER10 architected mode")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220519122205.746276-2-mpe@ellerman.id.au
CPU_FTRS_POWER9_DD2_2 is missing from CPU_FTRS_ALWAYS.
That doesn't cause any bug, because CPU_FTRS_POWER9_DD2_2 adds new bits
that don't appear in other values, so when anded with the other masks
the result is the same.
But for consistency we should have all values in the CPU_FTRS_ALWAYS
mask, so that the logic is robust against the values being changed in
future.
Fixes: b5af4f2793 ("powerpc: Add CPU feature bits for TM bug workarounds on POWER9 v2.2")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220519122205.746276-1-mpe@ellerman.id.au
The "oprofile" user-space tools don't use the kernel OPROFILE support
any more, and haven't in a long time. User-space has been converted to
the perf interfaces.
This commits stops building oprofile for powerpc and removes any
reference to it from directories in arch/powerpc/ apart from
arch/powerpc/oprofile, which will be removed in the next commit (this is
broken into two commits as the size of the commit became very big, ~5k
lines).
Note that the member "oprofile_cpu_type" in "struct cpu_spec" isn't
removed as it was also used by other parts of the code.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Robert Richter <rric@kernel.org>
Acked-by: William Cohen <wcohen@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
book3s/32 has two main families:
- CPU with 603 cores that don't have HASH PTE table and
perform SW TLB loading.
- Other CPUs based on 604+ cores that have HASH PTE table.
This leads to some complex logic and additionnal code to
support both. This makes sense for distribution kernels
that aim at running on any CPU, but when you are fine
tuning a kernel for an embedded 603 based board you
don't need all the HASH logic.
Allow selection of support for each family, in order to opt
out unneeded parts of code. At least one must be selected.
Note that some of the CPU supporting HASH also support SW TLB
loading, however it is not supported by Linux kernel at the
time being, because they do not have alternate registers in
the TLB miss exception handlers.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8dde0cdb629a71abc29b0d85a52a86e920376cb6.1603348103.git.christophe.leroy@csgroup.eu
There is no defconfig selecting CONFIG_E200, and no platform.
e200 is an earlier version of booke, a predecessor of e500,
with some particularities like an unified cache instead of both an
instruction cache and a data cache.
Remove it.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Scott Wood <oss@buserror.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/34ebc3ba2c768d97f363bd5f2deea2356e9ae127.1605589460.git.christophe.leroy@csgroup.eu
As stated in platform/44x/Kconfig, CONFIG_PPC_47x is not
compatible with 440 and 460 variants.
This is confirmed in asm/cache.h as L1_CACHE_SHIFT is different
for 47x, meaning a kernel built for 47x will not run correctly
on a 440.
In cputable, opt out all 440 and 460 variants when CONFIG_PPC_47x
is set. Also add a default match dedicated to 470.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/822833ce3dc10634339818f7d1ab616edf63b0c6.1603041883.git.christophe.leroy@csgroup.eu
MMU_FTR_PPCAS_ARCH_V2 is defined in cpu_table.h
as MMU_FTR_TLBIEL | MMU_FTR_16M_PAGE.
MMU_FTR_TLBIEL and MMU_FTR_16M_PAGE are defined in mmu.h
MMU_FTR_PPCAS_ARCH_V2 is used only in mmu.h and it is used only once.
Remove MMU_FTR_PPCAS_ARCH_V2 and use
directly MMU_FTR_TLBIEL | MMU_FTR_16M_PAGE
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/829ae1aed1d2fc6b5fc5818362e573dee5d6ecde.1602489852.git.christophe.leroy@csgroup.eu
In order to build VDSO32 for PPC64, we need to have CPU_FTRS_POSSIBLE
and CPU_FTRS_ALWAYS independant of whether we are building the
32 bits VDSO or the 64 bits VDSO.
Use #ifdef CONFIG_PPC64 instead of #ifdef __powerpc64__
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201126131006.2431205-1-mpe@ellerman.id.au
On 8xx, we get the following features:
[ 0.000000] cpu_features = 0x0000000000000100
[ 0.000000] possible = 0x0000000000000120
[ 0.000000] always = 0x0000000000000000
This is not correct. As CONFIG_PPC_8xx is mutually exclusive with all
other configurations, the three lines should be equal.
The problem is due to CPU_FTRS_GENERIC_32 which is taken when
CONFIG_BOOK3S_32 is NOT selected. This CPU_FTRS_GENERIC_32 is
pointless because there is no generic configuration supporting
all 32 bits but book3s/32.
Remove this pointless generic features definition to unbreak the
calculation of 'possible' features and 'always' features.
Fixes: 76bc080ef5 ("[POWERPC] Make default cputable entries reflect selected CPU family")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/76a85f30bf981d1aeaae00df99321235494da254.1604426550.git.christophe.leroy@csgroup.eu
ISA v3.1 removes transactional memory and hence it should not be present
in cpu_features or cpu_user_features2. Remove CPU_FTR_TM_COMP from
CPU_FTRS_POWER10. Remove PPC_FEATURE2_HTM_COMP and
PPC_FEATURE2_HTM_NOSC_COMP from COMMON_USER2_POWER10.
Fixes: a3ea40d5c7 ("powerpc: Add POWER10 architected mode")
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200827035529.900-1-jniethe5@gmail.com
PowerPC 601 has been retired.
Remove all associated specific code.
CPU_FTRS_PPC601 has CPU_FTR_COHERENT_ICACHE and CPU_FTR_COMMON.
CPU_FTR_COMMON is already present via other CPU_FTRS.
None of the remaining CPU selects CPU_FTR_COHERENT_ICACHE.
So CPU_FTRS_PPC601 can be removed from the possible features,
hence can be removed completely.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/60b725d55e21beec3335175c20b77903ff98284f.1601362098.git.christophe.leroy@csgroup.eu
Having cputable.h include mce.h means it pulls in a bunch of low level
headers (e.g., synch.h) which then can't use CPU_FTR_ definitions.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200916030234.4110379-1-npiggin@gmail.com
cpu_has_feature(CPU_FTR_SPE) returns false when CONFIG_SPE is
not set.
There is no need to enclose the test in an #ifdef CONFIG_SPE.
Remove it.
CPU_FTR_SPE only exists on 32 bits. Define it as 0 on 64 bits.
We have a couple of places like:
#ifdef CONFIG_SPE
if (cpu_has_feature(CPU_FTR_SPE)) {
do_something_that_requires_CONFIG_SPE
} else {
return -EINVAL;
}
#else
return -EINVAL;
#endif
Replace them by a cleaner version:
if (cpu_has_feature(CPU_FTR_SPE)) {
#ifdef CONFIG_SPE
do_something_that_requires_CONFIG_SPE
#endif
} else {
return -EINVAL;
}
When CONFIG_SPE is not set, this resolves to an unconditional
return of -EINVAL
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/698df8387555765b70ea42e4a7fa48141c309c1f.1597643221.git.christophe.leroy@csgroup.eu
This reverts commit 5c9fa16e8a.
Since PROT_SAO can still be useful for certain classes of software,
reintroduce it. Concerns about guest migration for LPARs using SAO
will be addressed next.
Signed-off-by: Shawn Anastasio <shawn@anastas.io>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200821185558.35561-2-shawn@anastas.io
__machine_check_early_realmode_p*() are currently declared as extern
in cputable.c and because of this when compiled with "C=1" (which
enables semantic checker) produces these warnings.
CHECK arch/powerpc/kernel/mce_power.c
arch/powerpc/kernel/mce_power.c:709:6: warning: symbol '__machine_check_early_realmode_p7' was not declared. Should it be static?
arch/powerpc/kernel/mce_power.c:717:6: warning: symbol '__machine_check_early_realmode_p8' was not declared. Should it be static?
arch/powerpc/kernel/mce_power.c:722:6: warning: symbol '__machine_check_early_realmode_p9' was not declared. Should it be static?
arch/powerpc/kernel/mce_power.c:740:6: warning: symbol '__machine_check_early_realmode_p10' was not declared. Should it be static?
Patch here moves the declaration to asm/mce.h and includes the same in
cputable.c
Fixes: ae744f3432 ("powerpc/book3s: Flush SLB/TLBs if we get SLB/TLB machine check errors on power8")
Fixes: 7b9f71f974 ("powerpc/64s: POWER9 machine check handler")
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200817005618.3305028-1-maddy@linux.ibm.com
So far Book3S Powerpc supported only one watchpoint. Power10 is
introducing 2nd DAWR. Enable 2nd DAWR support for Power10.
Availability of 2nd DAWR will depend on CPU_FTR_DAWR1.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-10-ravi.bangoria@linux.ibm.com
CPU_FTR_DAWR is by default enabled for host via CPU_FTRS_DT_CPU_BASE
(controlled by CONFIG_PPC_DT_CPU_FTRS). But cpu-features device-tree
node is not PAPR compatible and thus not yet used by kvm or pHyp
guests. Enable watchpoint functionality on power10 guest (both kvm
and powervm) by adding CPU_FTR_DAWR to CPU_FTRS_POWER10. Note that
this change does not enable 2nd DAWR support.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Tested-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-5-ravi.bangoria@linux.ibm.com
ISA v3.1 does not support the SAO storage control attribute required to
implement PROT_SAO. PROT_SAO was used by specialised system software
(Lx86) that has been discontinued for about 7 years, and is not thought
to be used elsewhere, so removal should not cause problems.
We rather remove it than keep support for older processors, because
live migrating guest partitions to newer processors may not be possible
if SAO is in use (or worse allowed with silent races).
- PROT_SAO stays in the uapi header so code using it would still build.
- arch_validate_prot() is removed, the generic version rejects PROT_SAO
so applications would get a failure at mmap() time.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Drop KVM change for the time being]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200703011958.1166620-3-npiggin@gmail.com
PVR value of 0x0F000006 means we are arch v3.1 compliant (i.e.
POWER10). This is used by phyp and kvm when booting as a pseries guest
to detect the presence of new P10 features and to enable the
appropriate hwcap and facility bits.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
[mpe: Fall through to __init_FSCR rather than duplicating it, drop
hack to set current->thread.fscr now that is handled elsewhere.]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-8-alistair@popple.id.au
Newer ISA versions are enabled by clearing all bits in the PCR
associated with previous versions of the ISA. Enable ISA v3.1 support
by updating the PCR mask to include ISA v3.0. This ensures all PCR
bits corresponding to earlier architecture versions get cleared
thereby enabling ISA v3.1 if supported by the hardware.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-3-alistair@popple.id.au
So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
But Power10 is introducing 2nd DAWR and thus kernel should be able to
dynamically find actual number of watchpoints supported by hw it's
running on. Introduce function for the same. Also convert HBP_NUM macro
to HBP_NUM_MAX, which will now represent maximum number of watchpoints
supported by Powerpc.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-4-ravi.bangoria@linux.ibm.com
Commit a25bd72bad ("powerpc/mm/radix: Workaround prefetch issue with
KVM") introduced a number of workarounds as coming out of a guest with
the mmu enabled would make the cpu would start running in hypervisor
state with the PID value from the guest. The cpu will then start
prefetching for the hypervisor with that PID value.
In Power9 DD2.2 the cpu behaviour was modified to fix this. When
accessing Quadrant 0 in hypervisor mode with LPID != 0 prefetching will
not be performed. This means that we can get rid of the workarounds for
Power9 DD2.2 and later revisions. Add a new cpu feature
CPU_FTR_P9_RADIX_PREFETCH_BUG to indicate if the workarounds are needed.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191206031722.25781-1-jniethe5@gmail.com
On POWER9, under some circumstances, a broadcast TLB invalidation will
fail to invalidate the ERAT cache on some threads when there are
parallel mtpidr/mtlpidr happening on other threads of the same core.
This can cause stores to continue to go to a page after it's unmapped.
The workaround is to force an ERAT flush using PID=0 or LPID=0 tlbie
flush. This additional TLB flush will cause the ERAT cache
invalidation. Since we are using PID=0 or LPID=0, we don't get
filtered out by the TLB snoop filtering logic.
We need to still follow this up with another tlbie to take care of
store vs tlbie ordering issue explained in commit:
a5d4b5891c ("powerpc/mm: Fixup tlbie vs store ordering issue on
POWER9"). The presence of ERAT cache implies we can still get new
stores and they may miss store queue marking flush.
Cc: stable@vger.kernel.org
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190924035254.24612-3-aneesh.kumar@linux.ibm.com
Rename the #define to indicate this is related to store vs tlbie
ordering issue. In the next patch, we will be adding another feature
flag that is used to handles ERAT flush vs tlbie ordering issue.
Fixes: a5d4b5891c ("powerpc/mm: Fixup tlbie vs store ordering issue on POWER9")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190924035254.24612-2-aneesh.kumar@linux.ibm.com
When the watchdog timer is set in interrupt mode, it causes a
machine check when it times out. The purpose of this mode is to
ease debugging, not to crash the kernel and reboot the machine.
This patch implements a special handling for that, in order to not
crash the kernel if the watchdog times out while in interrupt or
within the idle task.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[scottwood: added missing #include]
Signed-off-by: Scott Wood <oss@buserror.net>
The 603 doesn't have a HASH table, TLB misses are handled by
software. It is then possible to generate page fault when
_PAGE_EXEC is not set like in nohash/32.
There is one "reserved" PTE bit available, this patch uses
it for _PAGE_EXEC.
In order to support it, set_pte_filter() and
set_access_flags_filter() are made common, and the handling
is made dependent on MMU_FTR_HPTE_TABLE
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
files not using feature fixup don't need asm/feature-fixups.h
files using feature fixup need asm/feature-fixups.h
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch moves ASM_CONST() and stringify_in_c() into
dedicated asm-const.h, then cleans all related inclusions.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: asm-compat.h should include asm-const.h]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Merge in some commits we're sharing with the KVM tree.
I manually propagated the change from commit d3d4ffaae4
("powerpc/powernv/ioda2: Reduce upper limit for DMA window size") into
pci-ioda-tce.c.
Conflicts:
arch/powerpc/include/asm/cputable.h
arch/powerpc/platforms/powernv/pci-ioda.c
arch/powerpc/platforms/powernv/pci.h
POWER9 DD1 was never a product. It is no longer supported by upstream
firmware, and it is not effectively supported in Linux due to lack of
testing.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
[mpe: Remove arch_make_huge_pte() entirely]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This was added to support an early version of Power8 that did not have
working doorbells. These machines were not publicly available, and all of
the internal users have long since upgraded.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The cpu_has_feature() mechanism has an optimisation where at build
time we construct a mask of the CPU feature bits that will always be
true for the given .config, based on the platform/bitness/etc. that we
are building for.
That is incompatible with DT CPU features, where the set of CPU
features is dependent on feature flags that are given to us by
firmware.
The result is that some feature bits can not be *disabled* by DT CPU
features. Or more accurately, they can be disabled but they will still
appear in the ALWAYS mask, meaning cpu_has_feature() will always
return true for them.
In the past this hasn't really been a problem because on Book3S
64 (where we support DT CPU features), the set of ALWAYS bits has been
very small. That was because we always built for POWER4 and later,
meaning the set of common bits was small.
The only bit that could be cleared by DT CPU features that was also in
the ALWAYS mask was CPU_FTR_NODSISRALIGN, and that was only used in
the alignment handler to create a fake DSISR. That code was itself
deleted in 31bfdb036f ("powerpc: Use instruction emulation
infrastructure to handle alignment faults") (Sep 2017).
However the set of ALWAYS features changed with the recent commit
db5ae1c155 ("powerpc/64s: Refine feature sets for little endian
builds") which restricted the set of feature flags when building
little endian to Power7 or later. That caused the ALWAYS mask to
become much larger for little endian builds.
The result is that the following feature bits can currently not
be *disabled* by DT CPU features:
CPU_FTR_REAL_LE, CPU_FTR_MMCRA, CPU_FTR_CTRL, CPU_FTR_SMT,
CPU_FTR_PURR, CPU_FTR_SPURR, CPU_FTR_DSCR, CPU_FTR_PKEY,
CPU_FTR_VMX_COPY, CPU_FTR_CFAR, CPU_FTR_HAS_PPR.
To fix it we need to mask the set of ALWAYS features with the base set
of DT CPU features, ie. the features that are always enabled by DT CPU
features. That way there are no bits in the ALWAYS mask that are not
also always set by DT CPU features.
Fixes: db5ae1c155 ("powerpc/64s: Refine feature sets for little endian builds")
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
