When we treclaim and trecheckpoint there's an unavoidable period when r1
will not be a valid kernel stack pointer.

This patch clears the MSR recoverable interrupt (RI) bit over these
regions to indicate we have an invalid kernel stack pointer.

For treclaim, the region over which we clear MSR RI is larger than
required to avoid the need for an extra costly mtmsrd.

Thanks to Paulus for suggesting this change.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

String instruction emulation would erroneously result in a segfault if
the upper bits of the EA are set and is so high that it fails access
check.  Truncate the EA to 32 bits if the process is 32-bit.

Signed-off-by: James Yang <James.Yang@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: Sebastien Bessiere <sebastien.bessiere@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Currently, HPAGE_PMD_* constans rely on PMD_SHIFT regardless of
CONFIG_TRANSPARENT_HUGEPAGE.  PMD_SHIFT is not defined everywhere (e.g.
arm nommu case).

It means we can't use anything like this in generic code:

        if (PageTransHuge(page))
                zero_huge_user(page, 0, HPAGE_PMD_SIZE);
        else
                clear_highpage(page);

For !THP case, PageTransHuge() is 0 and compiler can eliminate
zero_huge_user() call.  But it still need to be valid C expression, means
HPAGE_PMD_SIZE has to expand to something compiler can understand.

Previously, HPAGE_PMD_* were defined to BUILD_BUG() for !THP. Let's come
back to it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

To replace down() with down_interrutible() to avoid following
warning:

[c00000007ba7b710] [c000000000014410] .__switch_to+0x1b0/0x380
[c00000007ba7b7c0] [c0000000007b408c] .__schedule+0x3ec/0x970
[c00000007ba7ba50] [c0000000007b1f24] .schedule_timeout+0x1a4/0x2b0
[c00000007ba7bb30] [c0000000007b34a4] .__down+0xa4/0x104
[c00000007ba7bbf0] [c0000000000b9230] .down+0x60/0x70
[c00000007ba7bc80] [c0000000000336d0] .eeh_event_handler+0x70/0x190
[c00000007ba7bd30] [c0000000000b1a58] .kthread+0xe8/0xf0
[c00000007ba7be30] [c00000000000a05c] .ret_from_kernel_thread+0x5c/0x8

This also avoids keeping the load average up while doing nothing.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Originally, eeh_mutex was introduced to protect the PE hierarchy
tree and the attached EEH devices because EEH core was possiblly
running with multiple threads to access the PE hierarchy tree.
However, we now have only one kthread in EEH core. So we needn't
the eeh_mutex and just remove it.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Building with CONFIG_TRANSPARENT_HUGEPAGE disabled causes the following
build wearnings;

powerpc/arch/powerpc/include/asm/mmu-hash64.h: In function ‘__hash_page_thp’:
powerpc/arch/powerpc/include/asm/mmu-hash64.h:354: warning: no return statement in function returning non-void

This patch adds a return -1 to the static inline for __hash_page_thp()
to correct the warnings.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Since now we have pstore support for nvram in pseries, enable it
in the default config. With this config option enabled, pstore
infra-structure will be used to read/write the messages from/to nvram.

Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

In 9422de3e

 "powerpc: Hardware breakpoints rewrite to handle non DABR breakpoint
registers" we changed the way we mark extraneous irqs with this:

-	info->extraneous_interrupt = !((bp->attr.bp_addr <= dar) &&
-			(dar - bp->attr.bp_addr < bp->attr.bp_len));
+	if (!((bp->attr.bp_addr <= dar) &&
+	      (dar - bp->attr.bp_addr < bp->attr.bp_len)))
+		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;

Unfortunately this is bogus as it never clears extraneous IRQ if it's already
set.

This correctly clears extraneous IRQ before possibly setting it.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Reported-by: Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The smallest match region for both the DABR and DAWR is 8 bytes, so the
kernel needs to filter matches when users want to look at regions smaller than
this.

Currently we set the length of PPC_BREAKPOINT_MODE_EXACT breakpoints to 8.
This is wrong as in exact mode we should only match on 1 address, hence the
length should be 1.

This ensures that the kernel will filter out any exact mode hardware breakpoint
matches on any addresses other than the requested one.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Reported-by: Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Hugepage invalidate involves invalidating multiple hpte entries.
Optimize the operation using H_BULK_REMOVE on lpar platforms.
On native, reduce the number of tlb flush.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We enable only if the we support 16MB page size.

Reviewed-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We find all the overlapping vma and mark them such that we don't allocate
hugepage in that range. Also we split existing huge page so that the
normal page hash can be invalidated and new page faulted in with new
protection bits.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

With THP we set pmd to none, before we do pte_clear. Hence we can't
walk page table to get the pte lock ptr and verify whether it is locked.
THP do take pte lock before calling pte_clear. So we don't change the locking
rules here. It is that we can't use page table walking to check whether
pte locks are held with THP.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

GCC is very likely to read the pagetables just once and cache them in
the local stack or in a register, but it is can also decide to re-read
the pagetables. The problem is that the pagetable in those places can
change from under gcc.

With THP/hugetlbfs the pmd (and pgd for hugetlbfs giga pages) can
change under gup_fast. The pages won't be freed untill we finish
gup fast because we have irq disabled and we free these pages via
rcu callback.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We need to have irqs disabled to handle all the possible parallel update for
linux page table without holding locks.

Events that we are intersted in while walking page tables are
1) Page fault
2) umap
3) THP split
4) THP collapse

A) local_irq_disabled:
------------------------
1) page fault:
A none to valid transition via page fault is not an issue because we
would either see a none or valid. If it is none, we would error out
the page table walk. We may need to use on stack values when checking for
type of page table elements, because if we do

if (!is_hugepd()) {
    if (!pmd_none() {
       if (pmd_bad() {

We could take that bad condition because the pmd got converted to a hugepd
after the !is_hugepd check via a hugetlb fault.

The right way would be to check for pmd_none higher up or use on stack value.

2) A valid to none conversion via unmap:
We can safely walk the upper level table, because we don't remove the the
page table entries until rcu grace period. So even if we followed a
wrong pointer we still have the pointer valid till the grace period.

A PTE pointer returned need to be atomically checked for _PAGE_PRESENT and
 _PAGE_BUSY. A valid pointer returned could becoming none later. To prevent
pte_clear we take _PAGE_BUSY.

3) THP split:
A valid transparent hugepage is converted to nomal page. Before we split we
do pmd_splitting_flush, which sets the hugepage PTE to _PAGE_SPLITTING
So when walking page table we need to check for pmd_trans_splitting and
handle that. The pte returned should also need to be checked for
_PAGE_SPLITTING before setting _PAGE_BUSY similar to _PAGE_PRESENT. We save
the value of PTE on stack and check for the flag in the local pte value.
If we don't have the value set we can safely operate on the local pte value
and we atomicaly set _PAGE_BUSY.

4) THP collapse:
A normal page gets converted to hugepage. In the collapse path, we
mark the pmd none early (pmdp_clear_flush). With irq disabled, if we
are aleady walking page table we would see the pmd_none and won't continue.
If we see a valid PMD, we should still check for _PAGE_PRESENT before
setting _PAGE_BUSY, to make sure we didn't collapse the PTE to a Huge PTE.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The deposted PTE page in the second half of the PMD table is used to
track the state on hash PTEs. After updating the HPTE, we mark the
coresponding slot in the deposted PTE page valid.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We can find pte that are splitting while walking page tables. Return
None pte in that case.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Replace find_linux_pte with find_linux_pte_or_hugepte and explicitly
document why we don't need to handle transparent hugepages at callsites.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Reviewed-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We will use this in the later patch for handling THP pages

Reviewed-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

We now have pmd entries covering 16MB range and the PMD table double its original size.
We use the second half of the PMD table to deposit the pgtable (PTE page).
The depoisted PTE page is further used to track the HPTE information. The information
include [ secondary group | 3 bit hidx | valid ]. We use one byte per each HPTE entry.
With 16MB hugepage and 64K HPTE we need 256 entries and with 4K HPTE we need
4096 entries. Both will fit in a 4K PTE page. On hugepage invalidate we need to walk
the PTE page and invalidate all valid HPTEs.

This patch implements necessary arch specific functions for THP support and also
hugepage invalidate logic. These PMD related functions are intentionally kept
similar to their PTE counter-part.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

THP code does PTE page allocation along with large page request and deposit them
for later use. This is to ensure that we won't have any failures when we split
hugepages to regular pages.

On powerpc we want to use the deposited PTE page for storing hash pte slot and
secondary bit information for the HPTEs. We use the second half
of the pmd table to save the deposted PTE page.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

If a hash bucket gets full, we "evict" a more/less random entry from it.
When we do that we don't invalidate the TLB (hpte_remove) because we assume
the old translation is still technically "valid". This implies that when
we are invalidating or updating pte, even if HPTE entry is not valid
we should do a tlb invalidate. With hugepages, we need to pass the correct
actual page size value for tlb invalidation.

This change update the patch 0608d692


"powerpc/mm: Always invalidate tlb on hpte invalidate and update" to handle
transparent hugepages correctly.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch creates debugfs entries (powerpc/PCIxxxx/err_injct) for
injecting EEH errors for testing purpose.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch creates one debugfs directory ("powerpc/PCIxxxx") for
each PHB so that we can hook EEH error injection debugfs entry
there in proceeding patch.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch registers OPAL event notifier and process the PCI errors
from firmware. If we have pending PCI errors, special EEH event
(without binding PE) will be sent to EEH core for processing.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

While we're restarting or powering off the system, we needn't
the OPAL notifier any more. So just to disable that.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This patch implements a notifier to receive a notification on OPAL
event mask changes. The notifier is only called as a result of an OPAL
interrupt, which will happen upon reception of FSP messages or PCI errors.
Any event mask change detected as a result of opal_poll_events() will not
result in a notifier call.

[benh: changelog]
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

It's meaningless to handle frozen PE if we already had fenced PHB.
The patch intends to check the PHB state before checking PE. If the
PHB has been put into fenced state, we need take care of that firstly.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch enables EEH check and let EEH core to process the EEH
errors for PowerNV platform while accessing config space. Originally,
the implementation already had mechanism to check EEH errors and
tried to recover from them. However, we never let EEH core to handle
the EEH errors.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch initializes EEH for PowerNV platform. Because the OPAL
APIs requires HUB ID, we need trace that through struct pnv_phb.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch adds EEH backends for PowerNV platform. It's notable that
part of those EEH backends call to the I/O chip dependent backends.

[Removed pointless change to eeh_pseries.c -- BenH]

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch implements the backend for EEH core to retrieve next
EEH error to handle. For the informational errors, we won't bother
the EEH core. Otherwise, the EEH should take appropriate actions
depending on the return value:

	0 - No further errors detected
	1 - Frozen PE
	2 - Fenced PHB
	3 - Dead PHB
	4 - Dead IOC

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch adds backends to retrieve error log and configure p2p
bridges for the indicated PE.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch adds the I/O chip backend to do PE reset. For now, we
focus on PCI bus dependent PE. If PHB PE has been put into error
state, the PHB will take complete reset. Besides, the root bridge
will take fundamental or hot reset accordingly if the indicated
PE locates at the toppest of PCI hierarchy tree. Otherwise, the
upstream p2p bridge will take hot reset.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch adds I/O chip backend to retrieve the state for the
indicated PE. While the PE state is temperarily unavailable,
the upper layer (powernv platform) should return default delay
(1 second).

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

The patch adds the backend to enable or disable EEH functionality
for the specified PE. The backend is also used to enable MMIO or
DMA path for the problematic PE. It's notable that all PEs on
PowerNV platform support EEH functionality by default, and we
disallow to disable EEH for the specific PE.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>