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Implement a method named pnv_get_proc_freq(unsigned int cpu) which
returns the current clock rate on the 'cpu' in Hz to be reported in
/proc/cpuinfo. This method uses the value reported by cpufreq when
such a value is sane. Otherwise it falls back to old way of reporting
the clockrate, i.e. ppc_proc_freq.
Set the ppc_md.get_proc_freq() hook to pnv_get_proc_freq() on the
PowerNV platform.
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Currently, the code in setup-common.c for powerpc assumes that all
clock rates are same in a smp system. This value is cached in the
variable named ppc_proc_freq and is the value that is reported in
/proc/cpuinfo.
However on the PowerNV platform, the clock rate is same only across
the threads of the same core. Hence the value that is reported in
/proc/cpuinfo is incorrect on PowerNV platforms. We need a better way
to query and report the correct value of the processor clock in
/proc/cpuinfo.
The patch achieves this by creating a machdep_call named
get_proc_freq() which is expected to returns the frequency in Hz. The
code in show_cpuinfo() can invoke this method to display the correct
clock rate on platforms that have implemented this method. On the
other powerpc platforms it can use the value cached in ppc_proc_freq.
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Firmware update on PowerNV platform takes several minutes. During
this time one CPU is stuck in FW and the kernel complains about "soft
lockups".
This patch returns all secondary CPUs to firmware before starting
firmware update process.
[ Reworked a bit and cleaned up -- BenH ]
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch updates the implementation of pci_process_bridge_OF_ranges to use
the of_pci_range_parser helpers.
Signed-off-by: Andrew Murray <amurray@embedded-bits.co.uk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch adds support to legacy serial for
UARTS with shifted registers.
The MVME5100 Single Board Computer is a PowerPC platform
that has 16550 style UARTS with register addresses that are
16 bytes apart (shifted by 4).
Commit 309257484cc1a592e8ac5fbdd8cd661be2b80bf8
"powerpc: Cleanup udbg_16550 and add support for LPC PIO-only UARTs"
added support to udbg_16550 for shifted registers by adding a "stride"
parameter to the initialisation operations for Programmed IO and
Memory Mapped IO.
As a consequence it is now possible to use the services of legacy serial
to provide early serial console messages for the MVME5100.
An added benefit of this is that the serial console will always be
"ttyS0" irrespective of whether the computer is fitted with extra
PCI 8250 interface boards or not.
I have tested this patch using the four PowerPC platforms available to me:
MVME5100 - shifted registers,
SAM440EP - unshifted registers,
MPC8349 - unshifted registers,
MVME4100 - unshifted registers.
Signed-off-by: Stephen Chivers <schivers@csc.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The code is only slightly modified : entry points now use the
FIXUP_ENDIAN trampoline to switch endian order. The 32bit wrapper
is kept for big endian kernels and 64bit is enforced for little
endian kernels with a PPC64_BOOT_WRAPPER config option.
The linker script is generated using the kernel preprocessor flags
to make use of the CONFIG_* definitions and the wrapper script is
modified to take into account the new elf64ppc format.
Finally, the zImage file is compiled as a position independent
executable (-pie) which makes it loadable at any address by the
firmware.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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When entering the boot wrapper in little endian, we will need to fix
the endian order using a fixup trampoline like in the kernel. This
patch overrides the _zimage_start entry point for this purpose.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch adds support a 64bit wrapper entry point. As in 32bit, the
entry point does its own relocation and can be loaded at any address
by the firmware.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch defines a 'prom' routine similar to 'enter_prom' in the
kernel.
The difference is in the MSR which is built before entering prom. Big
endian order is enforced as in the kernel but 32bit mode is not. It
prepares ground for the next patches which will introduce Little endian
order.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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It could certainly be improved using Elf macros and byteswapping
routines, but the initial version of the code is organised to be a
single file program with limited dependencies. yaboot is the same.
Please scream if you want a total rewrite.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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These are not the most efficient versions of swab but the wrapper does
not do much byte swapping. On a big endian cpu, these routines are
a no-op.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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arch/powerpc/boot/oflib.c:211:9: warning: cast to pointer from integer of \
different size [-Wint-to-pointer-cast]
return (phandle) of_call_prom("finddevice", 1, 1, name);
This is a work around. The definite solution would be to define the
phandle typedef as a u32, as in the kernel, but this would break the
device tree ops API.
Let it be for the moment.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This makes ihandle 64bit friendly.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch fixes 64bit compile warnings and updates the wrapper code
to converge the kernel code in prom_init.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This is mostly useful to make to the boot wrapper code closer with
the kernel code in prom_init.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Values will need to be byte-swapped when calling prom (big endian) from
a little endian boot wrapper.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch updates the wrapper code to converge with the kernel code in
prom_init.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch fixes warnings when the wrapper is compiled in 64bit and
updates the boot wrapper code related to prom to converge with the
kernel code in prom_init. This should make the review of changes easier.
The kernel has a different number of possible arguments (10) when
entering prom. There does not seem to be any good reason to have
12 in the wrapper, so the patch changes this value to args[10] in
the prom_args struct.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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When the boot wrapper is compiled in 64bit, there is no need to
use __div64_32.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Function early_init_dt_scan_fw_dump() is called to scan the device
tree for fdump properties under node "rtas". Any one of them is
invalid, we can stop scanning the device tree early by returning
"1". It would save a bit time during boot.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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If the PE contains single PCI function, "pe->pbus" would be NULL.
It's not reliable to be used by pci_domain_nr(). We just grab the
PCI domain number from the PCI host controller (struct pci_controller)
instance.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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In function pnv_pci_ioda2_setup_dma_pe(), the IOMMU table type is
set to (TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE) unconditionally.
It was just set to TCE_PCI by pnv_pci_setup_iommu_table(). So the
primary IOMMU table type (TCE_PCI) is lost. The patch fixes it.
Also, pnv_pci_setup_iommu_table() already set "tbl->it_busno" to
zero and we needn't do it again. The patch removes the redundant
assignment.
The patch also fixes similar issues in pnv_pci_ioda_setup_dma_pe().
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The patch intends to support fundamental reset on PLX downstream
ports. If the PCI device matches any one of the internal table,
which includes PLX vendor ID, bridge device ID, register offset
for fundamental reset and bit, fundamental reset will be done
accordingly. Otherwise, it will fail back to hot reset.
Additional flag (EEH_DEV_FRESET) is introduced to record the last
reset type on the PCI bridge.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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When PCI_ERS_RESULT_CAN_RECOVER returned from device drivers, the
EEH core should enable I/O and DMA for the affected PE. However,
it was missed to have DMA enabled in eeh_handle_normal_event().
Besides, the frozen state of the affected PE should be cleared
after successful recovery, but we didn't.
The patch fixes both of the issues as above.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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In the kdump scenario, the first kerenl doesn't shutdown PCI devices
and the kdump kerenl clean PHB IODA table at the early probe time.
That means the kdump kerenl can't support PCI transactions piled
by the first kerenl. Otherwise, lots of EEH errors and frozen PEs
will be detected.
In order to avoid the EEH errors, the PHB is resetted to drop all
PCI transaction from the first kerenl.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The problem was initially reported by Wendy who tried pass through
IPR adapter, which was connected to PHB root port directly, to KVM
based guest. When doing that, pci_reset_bridge_secondary_bus() was
called by VFIO driver and linkDown was detected by the root port.
That caused all PEs to be frozen.
The patch fixes the issue by routing the reset for the secondary bus
of root port to underly firmware. For that, one more weak function
pci_reset_secondary_bus() is introduced so that the individual platforms
can override that and do specific reset for bridge's secondary bus.
Reported-by: Wendy Xiong <wenxiong@linux.vnet.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Basically, we have 3 types of resets to fulfil PE reset: fundamental,
hot and PHB reset. For the later 2 cases, we need PCI bus reset hold
and settlement delay as specified by PCI spec. PowerNV and pSeries
platforms are running on top of different firmware and some of the
delays have been covered by underly firmware (PowerNV).
The patch makes the delays unified to be done in backend, instead of
EEH core.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Resetting root port has more stuff to do than that for PCIe switch
ports and we should have resetting root port done in firmware instead
of the kernel itself. The problem was introduced by commit 5b2e198e
("powerpc/powernv: Rework EEH reset").
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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In pseries_eeh_get_state(), EEH_STATE_UNAVAILABLE is always
overwritten by EEH_STATE_NOT_SUPPORT because of the missed
"break" there. The patch fixes the issue.
Reported-by: Joe Perches <joe@perches.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Once one specific PE has been marked as EEH_PE_ISOLATED, it's in
the middile of recovery or removed permenently. We needn't report
the frozen PE again. Otherwise, we will have endless reporting
same frozen PE.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The issue was detected in a bit complicated test case where
we have multiple hierarchical PEs shown as following figure:
+-----------------+
| PE#3 p2p#0 |
| p2p#1 |
+-----------------+
|
+-----------------+
| PE#4 pdev#0 |
| pdev#1 |
+-----------------+
PE#4 (have 2 PCI devices) is the child of PE#3, which has 2 p2p
bridges. We accidentally had less-known scenario: PE#4 was removed
permanently from the system because of permanent failure (e.g.
exceeding the max allowd failure times in last hour), then we detects
EEH errors on PE#3 and tried to recover it. However, eeh_dev instances
for pdev#0/1 were not detached from PE#4, which was still connected to
PE#3. All of that was because of the fact that we rely on count-based
pcibios_release_device(), which isn't reliable enough. When doing
recovery for PE#3, we still apply hotplug on PE#4 and pdev#0/1, which
are not valid any more. Eventually, we run into kernel crash.
The patch fixes above issue from two aspects. For unplug, we simply
skip those permanently removed PE, whose state is (EEH_PE_STATE_ISOLATED
&& !EEH_PE_STATE_RECOVERING) and its frozen count should be greater
than EEH_MAX_ALLOWED_FREEZES. For plug, we marked all permanently
removed EEH devices with EEH_DEV_REMOVED and return 0xFF's on read
its PCI config so that PCI core will omit them.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The patch introduces bootarg "eeh=off" to disable EEH functinality.
Also, it creates /sys/kerenl/debug/powerpc/eeh_enable to disable
or enable EEH functionality. By default, we have the functionality
enabled.
For PowerNV platform, we will restore to have the conventional
mechanism of clearing frozen PE during PCI config access if we're
going to disable EEH functionality. Conversely, we will rely on
EEH for error recovery.
The patch also fixes the issue that we missed to cover the case
of disabled EEH functionality in function ioda_eeh_event(). Those
events driven by interrupt should be cleared to avoid endless
reporting.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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There're 2 EEH subsystem variables: eeh_subsystem_enabled and
eeh_probe_mode. We needn't maintain 2 variables and we can just
have one variable and introduce different flags. The patch also
introduces additional flag EEH_FORCE_DISABLE, which will be used
to disable EEH subsystem via boot parameter ("eeh=off") in future.
Besides, the patch also introduces flag EEH_ENABLED, which is
changed to disable or enable EEH functionality on the fly through
debugfs entry in future.
With the patch applied, the creteria to check the enabled EEH
functionality is changed to:
!EEH_FORCE_DISABLED && EEH_ENABLED : Enabled
Other cases : Disabled
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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When calling into eeh_gather_pci_data() on pSeries platform, we
possiblly don't have pci_dev instance yet, but eeh_dev is always
ready. So we use cached capability from eeh_dev instead of pci_dev
for log dump there. In order to keep things unified, we also cache
PCI capability positions to eeh_dev for PowerNV as well.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The patch replaces printk(KERN_WARNING ...) with pr_warn() in the
function eeh_gather_pci_data().
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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We have suffered recrusive frozen PE a lot, which was caused
by IO accesses during the PE reset. Ben came up with the good
idea to keep frozen PE until recovery (BAR restore) gets done.
With that, IO accesses during PE reset are dropped by hardware
and wouldn't incur the recrusive frozen PE any more.
The patch implements the idea. We don't clear the frozen state
until PE reset is done completely. During the period, the EEH
core expects unfrozen state from backend to keep going. So we
have to reuse EEH_PE_RESET flag, which has been set during PE
reset, to return normal state from backend. The side effect is
we have to clear frozen state for towice (PE reset and clear it
explicitly), but that's harmless.
We have some limitations on pHyp. pHyp doesn't allow to enable
IO or DMA for unfrozen PE. So we don't enable them on unfrozen PE
in eeh_pci_enable(). We have to enable IO before grabbing logs on
pHyp. Otherwise, 0xFF's is always returned from PCI config space.
Also, we had wrong return value from eeh_pci_enable() for
EEH_OPT_THAW_DMA case. The patch fixes it too.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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For EEH PowerNV backends, they need use their own PCI config
accesors as the normal one could be blocked during PE reset.
The patch also removes necessary parameter "hose" for the
function ioda_eeh_bridge_reset().
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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We've observed multiple PE reset failures because of PCI-CFG
access during that period. Potentially, some device drivers
can't support EEH very well and they can't put the device to
motionless state before PE reset. So those device drivers might
produce PCI-CFG accesses during PE reset. Also, we could have
PCI-CFG access from user space (e.g. "lspci"). Since access to
frozen PE should return 0xFF's, we can block PCI-CFG access
during the period of PE reset so that we won't get recrusive EEH
errors.
The patch adds flag EEH_PE_RESET, which is kept during PE reset.
The PowerNV/pSeries PCI-CFG accessors reuse the flag to block
PCI-CFG accordingly.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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When doing PE reset, EEH_PE_ISOLATED is cleared unconditionally.
However, We should remove that if the PE reset has cleared the
frozen state successfully. Otherwise, the flag should be kept.
The patch fixes the issue.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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For some fields (e.g. LEM, MMIO, DMA) in PHB diag-data dump, it's
meaningless to print them if they have non-zero value in the
corresponding mask registers because we always have non-zero values
in the mask registers. The patch only prints those fieds if we
have non-zero values in the primary registers (e.g. LEM, MMIO, DMA
status) so that we can save couple of lines. The patch also removes
unnecessary spare line before "brdgCtl:" and two leading spaces as
prefix in each line as Ben suggested.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The flag PNV_EEH_STATE_ENABLED is put into pnv_phb::eeh_state,
which is protected by CONFIG_EEH. We needn't that. Instead, we
can have pnv_phb::flags and maintain all flags there, which is
the purpose of the patch. The patch also renames PNV_EEH_STATE_ENABLED
to PNV_PHB_FLAG_EEH.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The PHB state PNV_EEH_STATE_REMOVED maintained in pnv_phb isn't
so useful any more and it's duplicated to EEH_PE_ISOLATED. The
patch replaces PNV_EEH_STATE_REMOVED with EEH_PE_ISOLATED.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The PE state (for eeh_pe instance) EEH_PE_PHB_DEAD is duplicate to
EEH_PE_ISOLATED. Originally, those PHBs (PHB PE) with EEH_PE_PHB_DEAD
would be removed from the system. However, it's safe to replace
that with EEH_PE_ISOLATED.
The patch also clear EEH_PE_RECOVERING after fenced PHB has been handled,
either failure or success. It makes the PHB PE state consistent with:
PHB functions normally NONE
PHB has been removed EEH_PE_ISOLATED
PHB fenced, recovery in progress EEH_PE_ISOLATED | RECOVERING
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch fixes this section mismatch:
WARNING: vmlinux.o(.text+0x1efc4): Section mismatch in reference from
the function apm821xx_pciex_init_port_hw() to the function
.init.text:ppc4xx_pciex_wait_on_sdr.isra.9()
The function apm821xx_pciex_init_port_hw() references the function
__init ppc4xx_pciex_wait_on_sdr.isra.9(). This is often because
apm821xx_pciex_init_port_hw lacks a __init annotation or the
annotation of ppc4xx_pciex_wait_on_sdr.isra.9 is wrong.
apm821xx_pciex_init_port_hw is only referenced by a struct in
__initdata, so it should be safe to add __init to
apm821xx_pciex_init_port_hw.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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When the guest cedes the vcpu or the vcpu has no guest to
run it naps. Clear the runlatch bit of the vcpu before
napping to indicate an idle cpu.
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The secondary threads in the core are kept offline before launching guests
in kvm on powerpc: "371fefd6f2dc4666:KVM: PPC: Allow book3s_hv guests to use
SMT processor modes."
Hence their runlatch bits are cleared. When the secondary threads are called
in to start a guest, their runlatch bits need to be set to indicate that they
are busy. The primary thread has its runlatch bit set though, but there is no
harm in setting this bit once again. Hence set the runlatch bit for all
threads before they start guest.
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Up until now we have been setting the runlatch bits for a busy CPU and
clearing it when a CPU enters idle state. The runlatch bit has thus
been consistent with the utilization of a CPU as long as the CPU is online.
However when a CPU is hotplugged out the runlatch bit is not cleared. It
needs to be cleared to indicate an unused CPU. Hence this patch has the
runlatch bit cleared for an offline CPU just before entering an idle state
and sets it immediately after it exits the idle state.
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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While testing memory hot-remove, I found following dead lock:
Process #1141 is drmgr, trying to remove some memory, i.e. memory499.
It holds the memory_hotplug_mutex, and blocks when trying to remove file
"online" under dir memory499, in kernfs_drain(), at
wait_event(root->deactivate_waitq,
atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
Process #1120 is trying to online memory499 by
echo 1 > memory499/online
In .kernfs_fop_write, it uses kernfs_get_active() to increase
&kn->active, thus blocking process #1141. While itself is blocked later
when trying to acquire memory_hotplug_mutex, which is held by process
The backtrace of both processes are shown below:
[<c000000001b18600>] 0xc000000001b18600
[<c000000000015044>] .__switch_to+0x144/0x200
[<c000000000263ca4>] .online_pages+0x74/0x7b0
[<c00000000055b40c>] .memory_subsys_online+0x9c/0x150
[<c00000000053cbe8>] .device_online+0xb8/0x120
[<c00000000053cd04>] .online_store+0xb4/0xc0
[<c000000000538ce4>] .dev_attr_store+0x64/0xa0
[<c00000000030f4ec>] .sysfs_kf_write+0x7c/0xb0
[<c00000000030e574>] .kernfs_fop_write+0x154/0x1e0
[<c000000000268450>] .vfs_write+0xe0/0x260
[<c000000000269144>] .SyS_write+0x64/0x110
[<c000000000009ffc>] syscall_exit+0x0/0x7c
[<c000000001b18600>] 0xc000000001b18600
[<c000000000015044>] .__switch_to+0x144/0x200
[<c00000000030be14>] .__kernfs_remove+0x204/0x300
[<c00000000030d428>] .kernfs_remove_by_name_ns+0x68/0xf0
[<c00000000030fb38>] .sysfs_remove_file_ns+0x38/0x60
[<c000000000539354>] .device_remove_attrs+0x54/0xc0
[<c000000000539fd8>] .device_del+0x158/0x250
[<c00000000053a104>] .device_unregister+0x34/0xa0
[<c00000000055bc14>] .unregister_memory_section+0x164/0x170
[<c00000000024ee18>] .__remove_pages+0x108/0x4c0
[<c00000000004b590>] .arch_remove_memory+0x60/0xc0
[<c00000000026446c>] .remove_memory+0x8c/0xe0
[<c00000000007f9f4>] .pseries_remove_memblock+0xd4/0x160
[<c00000000007fcfc>] .pseries_memory_notifier+0x27c/0x290
[<c0000000008ae6cc>] .notifier_call_chain+0x8c/0x100
[<c0000000000d858c>] .__blocking_notifier_call_chain+0x6c/0xe0
[<c00000000071ddec>] .of_property_notify+0x7c/0xc0
[<c00000000071ed3c>] .of_update_property+0x3c/0x1b0
[<c0000000000756cc>] .ofdt_write+0x3dc/0x740
[<c0000000002f60fc>] .proc_reg_write+0xac/0x110
[<c000000000268450>] .vfs_write+0xe0/0x260
[<c000000000269144>] .SyS_write+0x64/0x110
[<c000000000009ffc>] syscall_exit+0x0/0x7c
This patch uses lock_device_hotplug() to protect remove_memory() called
in pseries_remove_memblock(), which is also stated before function
remove_memory():
* NOTE: The caller must call lock_device_hotplug() to serialize hotplug
* and online/offline operations before this call, as required by
* try_offline_node().
*/
void __ref remove_memory(int nid, u64 start, u64 size)
With this lock held, the other process(#1120 above) trying to online the
memory block will retry the system call when calling
lock_device_hotplug_sysfs(), and finally find No such device error.
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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module_init should return 0 or a negative errno.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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