Add a definition for cpu_show_spectre_v2() to override the generic
version. This has several permuations, though in practice some may not
occur we cater for any combination.

The most verbose is:

  Mitigation: Indirect branch serialisation (kernel only), Indirect
  branch cache disabled, ori31 speculation barrier enabled

We don't treat the ori31 speculation barrier as a mitigation on its
own, because it has to be *used* by code in order to be a mitigation
and we don't know if userspace is doing that. So if that's all we see
we say:

  Vulnerable, ori31 speculation barrier enabled
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add a definition for cpu_show_spectre_v1() to override the generic
version. Currently this just prints "Not affected" or "Vulnerable"
based on the firmware flag.

Although the kernel does have array_index_nospec() in a few places, we
haven't yet audited all the powerpc code to see where it's necessary,
so for now we don't list that as a mitigation.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Now that we have the security flags we can simplify the code in
pseries_setup_rfi_flush() because the security flags have pessimistic
defaults.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Now that we have the security flags we can significantly simplify the
code in pnv_setup_rfi_flush(), because we can use the flags instead of
checking device tree properties and because the security flags have
pessimistic defaults.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Now that we have the security feature flags we can make the
information displayed in the "meltdown" file more informative.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This landed in setup_64.c for no good reason other than we had nowhere
else to put it. Now that we have a security-related file, that is a
better place for it so move it.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Now that we have feature flags for security related things, set or
clear them based on what we see in the device tree provided by
firmware.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Now that we have feature flags for security related things, set or
clear them based on what we receive from the hypercall.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This commit adds security feature flags to reflect the settings we
receive from firmware regarding Spectre/Meltdown mitigations.

The feature names reflect the names we are given by firmware on bare
metal machines. See the hostboot source for details.

Arguably these could be firmware features, but that then requires them
to be read early in boot so they're available prior to asm feature
patching, but we don't actually want to use them for patching. We may
also want to dynamically update them in future, which would be
incompatible with the way firmware features work (at the moment at
least). So for now just make them separate flags.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add some additional values which have been defined for the
H_GET_CPU_CHARACTERISTICS hypercall.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We might have migrated to a machine that uses a different flush type,
or doesn't need flushing at all.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NMauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Currently the rfi-flush messages print 'Using <type> flush' for all
enabled_flush_types, but that is not necessarily true -- as now the
fallback flush is always enabled on pseries, but the fixup function
overwrites its nop/branch slot with other flush types, if available.

So, replace the 'Using <type> flush' messages with '<type> flush is
available'.

Also, print the patched flush types in the fixup function, so users
can know what is (not) being used (e.g., the slower, fallback flush,
or no flush type at all if flush is disabled via the debugfs switch).
Suggested-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NMauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This ensures the fallback flush area is always allocated on pseries,
so in case a LPAR is migrated from a patched to an unpatched system,
it is possible to enable the fallback flush in the target system.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NMauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

For PowerVM migration we want to be able to call setup_rfi_flush()
again after we've migrated the partition.

To support that we need to check that we're not trying to allocate the
fallback flush area after memblock has gone away (i.e., boot-time only).
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NMauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

rfi_flush_enable() includes a check to see if we're already
enabled (or disabled), and in that case does nothing.

But that means calling setup_rfi_flush() a 2nd time doesn't actually
work, which is a bit confusing.

Move that check into the debugfs code, where it really belongs.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NMauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

These events either do not count, or do not count correctly, so to
prevent user confusion block counting them at all.
Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Change log]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

These events either do not count, or do not count correctly, so to
prevent user confusion block counting them at all.
Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Change log]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Introduce code to support addition of blacklisted events for a
processor version. Blacklisted events are events that are known to not
count correctly on that CPU revision, and so should be prevented from
being counted so as to avoid user confusion.

A 'pointer' and 'int' variable to hold the number of events are added
to 'struct power_pmu', along with a generic function to loop through
the list to validate the given event. Generic function
'is_event_blacklisted' is called in power_pmu_event_init() to detect
and reject early.
Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Sampled Data Address Register (SDAR) is a 64-bit register that
contains the effective address of the storage operand of an
instruction that was being executed, possibly out-of-order, at or
around the time that the Performance Monitor alert occurred.

In certain scenario SDAR happen to contain the kernel address even for
userspace only sampling. Add checks to prevent it.
Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The current Branch History Rolling Buffer (BHRB) code does not check
for any privilege levels before updating the data from BHRB. This
could leak kernel addresses to userspace even when profiling only with
userspace privileges. Add proper checks to prevent it.
Acked-by: NBalbir Singh <bsingharora@gmail.com>
Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Current code in power_pmu_disable() does not clear the sampling
registers like Sampling Instruction Address Register (SIAR) and
Sampling Data Address Register (SDAR) after disabling the PMU. Since
these are userspace readable and could contain kernel addresses, add
code to explicitly clear the content of these registers.

Also add a "context synchronizing instruction" to enforce no further
updates to these registers as suggested by Power ISA v3.0B. From
section 9.4, on page 1108:

  "If an mtspr instruction is executed that changes the value of a
  Performance Monitor register other than SIAR, SDAR, and SIER, the
  change is not guaranteed to have taken effect until after a
  subsequent context synchronizing instruction has been executed (see
  Chapter 11. "Synchronization Requirements for Context Alterations"
  on page 1133)."
Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Massage change log and add ISA reference]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

On POWER9, since commit cc3d2940 ("powerpc/64: Enable use of radix
MMU under hypervisor on POWER9", 2017-01-30), we set both the radix and
HPT bits in the client-architecture-support (CAS) vector, which tells
the hypervisor that we can do either radix or HPT.  According to PAPR,
if we use this combination we are promising to do a H_REGISTER_PROC_TBL
hcall later on to let the hypervisor know whether we are doing radix
or HPT.  We currently do this call if we are doing radix but not if
we are doing HPT.  If the hypervisor is able to support both radix
and HPT guests, it would be entitled to defer allocation of the HPT
until the H_REGISTER_PROC_TBL call, and to fail any attempts to create
HPTEs until the H_REGISTER_PROC_TBL call.  Thus we need to do a
H_REGISTER_PROC_TBL call when we are doing HPT; otherwise we may
crash at boot time.

This adds the code to call H_REGISTER_PROC_TBL in this case, before
we attempt to create any HPT entries using H_ENTER.

Fixes: cc3d2940 ("powerpc/64: Enable use of radix MMU under hypervisor on POWER9")
Cc: stable@vger.kernel.org # v4.11+
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Reviewed-by: NSuraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This brings in two series from Paul, one of which touches KVM code and
may need to be merged into the kvm-ppc tree to resolve conflicts.

This works around a hardware bug in "Nimbus" POWER9 DD2.2 processors,
where the contents of the TEXASR can get corrupted while a thread is
in fake suspend state.  The workaround is for the instruction emulation
code to use the value saved at the most recent guest exit in real
suspend mode.  We achieve this by simply not saving the TEXASR into
the vcpu struct on an exit in fake suspend state.  We also have to
take care to set the orig_texasr field only on guest exit in real
suspend state.

This also means that on guest entry in fake suspend state, TEXASR
will be restored to the value it had on the last exit in real suspend
state, effectively counteracting any hardware-caused corruption.  This
works because TEXASR may not be written in suspend state.

With this, the guest might see the wrong values in TEXASR if it reads
it while in suspend state, but will see the correct value in
non-transactional state (e.g. after a treclaim), and treclaim will
work correctly.

With this workaround, the code will actually run slightly faster, and
will operate correctly on systems without the TEXASR bug (since TEXASR
may not be written in suspend state, and is only changed by failure
recording, which will have already been done before we get into fake
suspend state).  Therefore these changes are not made subject to a CPU
feature bit.
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This works around a hardware bug in "Nimbus" POWER9 DD2.2 processors,
where a treclaim performed in fake suspend mode can cause subsequent
reads from the XER register to return inconsistent values for the SO
(summary overflow) bit.  The inconsistent SO bit state can potentially
be observed on any thread in the core.  We have to do the treclaim
because that is the only way to get the thread out of suspend state
(fake or real) and into non-transactional state.

The workaround for the bug is to force the core into SMT4 mode before
doing the treclaim.  This patch adds the code to do that, conditional
on the CPU_FTR_P9_TM_XER_SO_BUG feature bit.
Signed-off-by: NSuraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

POWER9 has hardware bugs relating to transactional memory and thread
reconfiguration (changes to hardware SMT mode).  Specifically, the core
does not have enough storage to store a complete checkpoint of all the
architected state for all four threads.  The DD2.2 version of POWER9
includes hardware modifications designed to allow hypervisor software
to implement workarounds for these problems.  This patch implements
those workarounds in KVM code so that KVM guests see a full, working
transactional memory implementation.

The problems center around the use of TM suspended state, where the
CPU has a checkpointed state but execution is not transactional.  The
workaround is to implement a "fake suspend" state, which looks to the
guest like suspended state but the CPU does not store a checkpoint.
In this state, any instruction that would cause a transition to
transactional state (rfid, rfebb, mtmsrd, tresume) or would use the
checkpointed state (treclaim) causes a "soft patch" interrupt (vector
0x1500) to the hypervisor so that it can be emulated.  The trechkpt
instruction also causes a soft patch interrupt.

On POWER9 DD2.2, we avoid returning to the guest in any state which
would require a checkpoint to be present.  The trechkpt in the guest
entry path which would normally create that checkpoint is replaced by
either a transition to fake suspend state, if the guest is in suspend
state, or a rollback to the pre-transactional state if the guest is in
transactional state.  Fake suspend state is indicated by a flag in the
PACA plus a new bit in the PSSCR.  The new PSSCR bit is write-only and
reads back as 0.

On exit from the guest, if the guest is in fake suspend state, we still
do the treclaim instruction as we would in real suspend state, in order
to get into non-transactional state, but we do not save the resulting
register state since there was no checkpoint.

Emulation of the instructions that cause a softpatch interrupt is
handled in two paths.  If the guest is in real suspend mode, we call
kvmhv_p9_tm_emulation_early() to handle the cases where the guest is
transitioning to transactional state.  This is called before we do the
treclaim in the guest exit path; because we haven't done treclaim, we
can get back to the guest with the transaction still active.  If the
instruction is a case that kvmhv_p9_tm_emulation_early() doesn't
handle, or if the guest is in fake suspend state, then we proceed to
do the complete guest exit path and subsequently call
kvmhv_p9_tm_emulation() in host context with the MMU on.  This handles
all the cases including the cases that generate program interrupts
(illegal instruction or TM Bad Thing) and facility unavailable
interrupts.

The emulation is reasonably straightforward and is mostly concerned
with checking for exception conditions and updating the state of
registers such as MSR and CR0.  The treclaim emulation takes care to
ensure that the TEXASR register gets updated as if it were the guest
treclaim instruction that had done failure recording, not the treclaim
done in hypervisor state in the guest exit path.

With this, the KVM_CAP_PPC_HTM capability returns true (1) even if
transactional memory is not available to host userspace.
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

POWER9 processors up to and including "Nimbus" v2.2 have hardware
bugs relating to transactional memory and thread reconfiguration.
One of these bugs has a workaround which is to get the core into
SMT4 state temporarily.  This workaround is only needed when
running bare-metal.

This patch provides a function which gets the core into SMT4 mode
by preventing threads from going to a stop state, and waking up
those which are already in a stop state.  Once at least 3 threads
are not in a stop state, the core will be in SMT4 and we can
continue.

To do this, we add a "dont_stop" flag to the paca to tell the
thread not to go into a stop state.  If this flag is set,
power9_idle_stop() just returns immediately with a return value
of 0.  The pnv_power9_force_smt4_catch() function does the following:

1. Set the dont_stop flag for each thread in the core, except
   ourselves (in fact we use an atomic_inc() in case more than
   one thread is calling this function concurrently).
2. See how many threads are awake, indicated by their
   requested_psscr field in the paca being 0.  If this is at
   least 3, skip to step 5.
3. Send a doorbell interrupt to each thread that was seen as
   being in a stop state in step 2.
4. Until at least 3 threads are awake, scan the threads to which
   we sent a doorbell interrupt and check if they are awake now.

This relies on the following properties:

- Once dont_stop is non-zero, requested_psccr can't go from zero to
  non-zero, except transiently (and without the thread doing stop).
- requested_psscr being zero guarantees that the thread isn't in
  a state-losing stop state where thread reconfiguration could occur.
- Doing stop with a PSSCR value of 0 won't be a state-losing stop
  and thus won't allow thread reconfiguration.
- Once threads_per_core/2 + 1 (i.e. 3) threads are awake, the core
  must be in SMT4 mode, since SMT modes are powers of 2.

This does add a sync to power9_idle_stop(), which is necessary to
provide the correct ordering between setting requested_psscr and
checking dont_stop.  The overhead of the sync should be unnoticeable
compared to the latency of going into and out of a stop state.

Because some objected to incurring this extra latency on systems where
the XER[SO] bug is not relevant, I have put the test in
power9_idle_stop inside a feature section.  This means that
pnv_power9_force_smt4_catch() WILL NOT WORK correctly on systems
without the CPU_FTR_P9_TM_XER_SO_BUG feature bit set, and will
probably hang the system.

In order to cater for uses where the caller has an operation that
has to be done while the core is in SMT4, the core continues to be
kept in SMT4 after pnv_power9_force_smt4_catch() function returns,
until the pnv_power9_force_smt4_release() function is called.
It undoes the effect of step 1 above and allows the other threads
to go into a stop state.
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This adds a CPU feature bit which is set for POWER9 "Nimbus" DD2.2
processors which will be used to enable the hypervisor to assist
hardware with the handling of checkpointed register values while the
CPU is in suspend state, in order to work around hardware bugs.  The
hardware assistance for these workarounds introduced a new hardware
bug relating to the XER[SO] bit.  We add a separate feature bit for
this bug in case future chips fix it while still requiring the
hypervisor assistance with suspend state.

When the dt_cpu_ftrs subsystem is in use, the software assistance can
be enabled using a "tm-suspend-hypervisor-assist" node in the device
tree, and a "tm-suspend-xer-so-bug" node enables the workarounds for
the XER[SO] bug.  In the absence of such nodes, a quirk enables both
for POWER9 "Nimbus" DD2.2 processors.
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This moves all the CPU feature bits that are only used on 32-bit
machines to the top 20 bits of the CPU feature word and arranges
for them to be defined only in 32-bit builds.  The features that
are common to 32-bit and 64-bit machines are moved to bits 0-11
of the CPU feature word.  This means that for 64-bit platforms,
bits 44-63 can now be used for new features that only exist on
64-bit machines.  (These bit numbers are counting from the right,
i.e. the LSB is bit 0.)

Because CPU_FTR_L3_DISABLE_NAP moved from the low 16 bits to the high
16 bits, we have to adjust some assembly code.  Also, CPU_FTR_EMB_HV
moved from the high 16 bits to the low 16 bits.

Note that CPU_FTR_REAL_LE only applies to 64-bit chips, because only
64-bit chips (POWER6, 7, 8, 9) have a true little-endian mode that is
a CPU execution mode as opposed to being a page attribute.

With this we now have 20 free CPU feature bits on 64-bit machines.
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The CPU_FTR_L2CSR bit is never tested anywhere, so let's reclaim the
bit.

The last usage was removed in 86d63363 ("powerpc/e500mc: Remove
dead L2 flushing code in idle_e500.S") (Jun 2015).
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

All PowerPC CPUs other than the original PPC601 have a timebase
register rather than the "real-time clock" (RTC) register that the
PPC601 (and the original POWER and POWER2 CPUs) had.  Currently
we have a CPU feature bit to indicate the presence of the timebase,
but it makes more sense to use a bit to indicate the unusual
situation rather than the common situation.  This therefore defines
a CPU_FTR_USE_RTC bit in place of the CPU_FTR_USE_TB bit, and
arranges for it to be set on PPC601 systems.
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

'linux,stdout-path' has been deprecated for some time in favor of
'stdout-path'. Now dtc will warn on occurrences of 'linux,stdout-path'.
Search and replace all the of occurrences with 'stdout-path'.
Signed-off-by: NRob Herring <robh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
[mpe: Add SPDX, and fixup formatting]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

It's slightly less error prone to use sizeof(*foo) rather than
specifying the type.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
[mpe: Consolidate into one patch, rewrite change log]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The flush_dcache_phys_range() function is no longer used in the
kernel. The last usage was removed in c40785ad ("powerpc/dart: Use
a cachable DART").

This patch removes the function and declaration.
Signed-off-by: NMatt Brown <matthew.brown.dev@gmail.com>
[mpe: Munge change log, include commit that removed last user]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Previously the raid6 test Makefile did not build the POWER specific files
(altivec and vpermxor).
This patch fixes the bug, so that all appropriate files for powerpc are built.

This patch also fixes the missing and mismatched ifdef statements to allow the
altivec.uc file to be built correctly.
Signed-off-by: NMatt Brown <matthew.brown.dev@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This patch uses the vpermxor instruction to optimise the raid6 Q
syndrome. This instruction was made available with POWER8, ISA version
2.07. It allows for both vperm and vxor instructions to be done in a
single instruction. This has been tested for correctness on a ppc64le
vm with a basic RAID6 setup containing 5 drives.

The performance benchmarks are from the raid6test in the
/lib/raid6/test directory. These results are from an IBM Firestone
machine with ppc64le architecture. The benchmark results show a 35%
speed increase over the best existing algorithm for powerpc (altivec).
The raid6test has also been run on a big-endian ppc64 vm to ensure it
also works for big-endian architectures.

Performance benchmarks:
  raid6: altivecx4 gen() 18773 MB/s
  raid6: altivecx8 gen() 19438 MB/s

  raid6: vpermxor4 gen() 25112 MB/s
  raid6: vpermxor8 gen() 26279 MB/s
Signed-off-by: NMatt Brown <matthew.brown.dev@gmail.com>
Reviewed-by: NDaniel Axtens <dja@axtens.net>
[mpe: Add VPERMXOR macro so we can build with old binutils]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The proper compatible for rv3029 is microcrystal,rv3029.
Acked-by: NAnatolij Gustschin <agust@denx.de>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The RTC core is always calling rtc_valid_tm after the read_time callback.
It is not necessary to call it just before returning from the callback.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Add a couple of trace points in the VAS driver
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
[mpe: Add SPDX tag to new header]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>