kernel.git/arch/powerpc/kernel/dt_cpu_ftrs.c, branch linux-4.17.y

powerpc/64s: Fix DT CPU features Power9 DD2.1 logic

2018-07-03T09:26:51Z

commit 749a0278c2177b2d16da5d8b135ba7f940bb4199 upstream. In the device tree CPU features quirk code we want to set CPU_FTR_POWER9_DD2_1 on all Power9s that aren't DD2.0 or earlier. But we got the logic wrong and instead set it on all CPUs that aren't Power9 DD2.0 or earlier, ie. including Power8. Fix it by making sure we're on a Power9. This isn't a bug in practice because the only code that checks the feature is Power9 only to begin with. But we'll backport it anyway to avoid confusion. Fixes: 9e9626ed3a4a ("powerpc/64s: Fix POWER9 DD2.2 and above in DT CPU features") Cc: stable@vger.kernel.org # v4.17+ Reported-by: Paul Mackerras Signed-off-by: Michael Ellerman Acked-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Clear PCR on boot

2018-05-18T06:05:15Z

Clear the PCR (Processor Compatibility Register) on boot to ensure we are not running in a compatibility mode. We've seen this cause problems when a crash (and kdump) occurs while running compat mode guests. The kdump kernel then runs with the PCR set and causes problems. The symptom in the kdump kernel (also seen in petitboot after fast-reboot) is early userspace programs taking sigills on newer instructions (seen in libc). Signed-off-by: Michael Neuling Cc: stable@vger.kernel.org Signed-off-by: Michael Ellerman

powerpc/64s: Fix CPU_FTRS_ALWAYS vs DT CPU features

2018-04-13T13:51:44Z

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 31bfdb036f12 ("powerpc: Use instruction emulation infrastructure to handle alignment faults") (Sep 2017). However the set of ALWAYS features changed with the recent commit db5ae1c155af ("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: db5ae1c155af ("powerpc/64s: Refine feature sets for little endian builds") Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s: Fix pkey support in dt_cpu_ftrs, add CPU_FTR_PKEY bit

2018-04-05T06:28:00Z

The pkey code added a CPU_FTR_PKEY bit, but did not add it to the dt_cpu_ftrs feature set. Although capability is supported by all processors in the base dt_cpu_ftrs set for 64s, it's a significant and sufficiently well defined feature to make it optional. So add it as a quirk for now, which can be versioned out then controlled by the firmware (once dt_cpu_ftrs gains versioning support). Fixes: cf43d3b26452 ("powerpc: Enable pkey subsystem") Cc: stable@vger.kernel.org # v4.16+ Cc: Ram Pai Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s: Fix dt_cpu_ftrs to have restore_cpu clear unwanted LPCR bits

2018-04-05T06:10:36Z

Presently the dt_cpu_ftrs restore_cpu will only add bits to the LPCR for secondaries, but some bits must be removed (e.g., UPRT for HPT). Not clearing these bits on secondaries causes checkstops when booting with disable_radix. restore_cpu can not just set LPCR, because it is also called by the idle wakeup code which relies on opal_slw_set_reg to restore the value of LPCR, at least on P8 which does not save LPCR to stack in the idle code. Fix this by including a mask of bits to clear from LPCR as well, which is used by restore_cpu. This is a little messy now, but it's a minimal fix that can be backported. Longer term, the idle SPR save/restore code can be reworked to completely avoid calls to restore_cpu, then restore_cpu would be able to unconditionally set LPCR to match boot processor environment. Fixes: 5a61ef74f269f ("powerpc/64s: Support new device tree binding for discovering CPU features") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s: Fix POWER9 DD2.2 and above in DT CPU features

2018-03-31T13:47:49Z

The CPU_FTR_POWER9_DD2_1 flag is intended to be set for DD2.1 and above (which is what the cputable setup does). Fix DT CPU features quirk setup to match. Signed-off-by: Nicholas Piggin [mpe: Merge with upstream changes] Signed-off-by: Michael Ellerman

Merge branch 'fixes' into next

2018-03-28T11:59:50Z

Merge our fixes branch from the 4.16 cycle. There were a number of important fixes merged, in particular some Power9 workarounds that we want in next for testing purposes. There's also been some conflicting changes in the CPU features code which are best merged and tested before going upstream.

powerpc: Disable DAWR on POWER9 via CPU feature quirk

2018-03-27T12:55:33Z

This disables the DAWR on all POWER9 CPUs via cpu feature quirk. Using the DAWR on POWER9 can cause xstops, hence we need to disable it. Signed-off-by: Michael Neuling Signed-off-by: Michael Ellerman

powerpc: Add CPU feature bits for TM bug workarounds on POWER9 v2.2

2018-03-23T13:39:09Z

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: Paul Mackerras Signed-off-by: Michael Ellerman

powerpc: Use feature bit for RTC presence rather than timebase presence

2018-03-23T13:36:45Z

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: Paul Mackerras Signed-off-by: Michael Ellerman