powerpc: Fix all occurences of duplicate words

Since commit 87c78b612f4f ("powerpc: Fix all occurences of "the the"")
fixed "the the", there's now a steady stream of patches fixing other
duplicate words.

Just fix them all at once, to save the overhead of dealing with
individual patches for each case.

This leaves a few cases of "that that", which in some contexts is
correct.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220718095158.326606-1-mpe@ellerman.id.au

powerpc/powernv/vas: Assign real address to rx_fifo in vas_rx_win_attr

In init_winctx_regs(), __pa() is called on winctx->rx_fifo and this
function is called to initialize registers for receive and fault
windows. But the real address is passed in winctx->rx_fifo for
receive windows and the virtual address for fault windows which
causes errors with DEBUG_VIRTUAL enabled. Fixes this issue by
assigning only real address to rx_fifo in vas_rx_win_attr struct
for both receive and fault windows.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/338e958c7ab8f3b266fa794a1f80f99b9671829e.camel@linux.ibm.com

powerpc/vas: Define and use common vas_window struct

Many elements in vas_struct are used on PowerNV and PowerVM
platforms. vas_window is used for both TX and RX windows on
PowerNV and for TX windows on PowerVM. So some elements are
specific to these platforms.

So this patch defines common vas_window and platform
specific window structs (pnv_vas_window on PowerNV). Also adds
the corresponding changes in PowerNV vas code.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1698c35c158dfe52c6d2166667823d3d4a463353.camel@linux.ibm.com

powerpc/vas: Move update_csb/dump_crb to common book3s platform

If a coprocessor encounters an error translating an address, the
VAS will cause an interrupt in the host. The kernel processes
the fault by updating CSB. This functionality is same for both
powerNV and pseries. So this patch moves these functions to
common vas-api.c and the actual functionality is not changed.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bf8d5b0770fa1ef5cba88c96580caa08d999d3b5.camel@linux.ibm.com

powerpc/vas: Create take/drop pid and mm reference functions

Take pid and mm references when each window opens and drops during
close. This functionality is needed for powerNV and pseries. So
this patch defines the existing code as functions in common book3s
platform vas-api.c

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2fa40df962250a737c804e58202924717b39e381.camel@linux.ibm.com

powerpc/vas: Report proper error code for address translation failure

P9 DD2 NX workbook (Table 4-36) says DMA controller uses CC=5
internally for translation fault handling. NX reserves CC=250 for
OS to notify user space when NX encounters address translation
failure on the request buffer. Not an issue in earlier releases
as NX does not get faults on kernel addresses.

This patch defines CSB_CC_FAULT_ADDRESS(250) and updates CSB.CC with
this proper error code for user space.

Fixes: c96c4436aba4 ("powerpc/vas: Update CSB and notify process for fault CRBs")
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
[mpe: Added Fixes tag and fix typo in comment]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/019fd53e7538c6f8f332d175df74b1815ef5aa8c.camel@linux.ibm.com

kernel: better document the use_mm/unuse_mm API contract

Switch the function documentation to kerneldoc comments, and add
WARN_ON_ONCE asserts that the calling thread is a kernel thread and does
not have ->mm set (or has ->mm set in the case of unuse_mm).

Also give the functions a kthread_ prefix to better document the use case.

[hch@lst.de: fix a comment typo, cover the newly merged use_mm/unuse_mm caller in vfio]
Link: http://lkml.kernel.org/r/20200416053158.586887-3-hch@lst.de
[sfr@canb.auug.org.au: powerpc/vas: fix up for {un}use_mm() rename]
Link: http://lkml.kernel.org/r/20200422163935.5aa93ba5@canb.auug.org.au

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [usb]
Acked-by: Haren Myneni <haren@linux.ibm.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Link: http://lkml.kernel.org/r/20200404094101.672954-6-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

powerpc/vas: Print CRB and FIFO values

Dump FIFO entries if could not find send window and print CRB
for debugging.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587017099.2275.1067.camel@hbabu-laptop

powerpc/vas: Return credits after handling fault

NX uses credit mechanism to control the number of requests issued on
a specific window at any point of time. Only send windows and fault
window are used credits. When the request is issued on a given window,
a credit is taken. This credit will be returned after that request is
processed. If credits are not available, returns RMA_Busy for send
window and RMA_Reject for fault window.

NX expects OS to return credit for send window after processing fault
CRB. Also credit has to be returned for fault window after handling
the fault.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587017059.2275.1064.camel@hbabu-laptop

powerpc/vas: Update CSB and notify process for fault CRBs

Applications polls on CSB for the status update after requests are
issued. NX process these requests and update the CSB with the status.
If it encounters translation error, pastes CRB in fault FIFO and
raises an interrupt. The kernel handles fault by reading CRB from
fault FIFO and process the fault CRB.

For each fault CRB, update fault address in CRB (fault_storage_addr)
and translation error status in CSB so that user space can touch the
fault address and resend the request. If the user space passed invalid
CSB address send signal to process with SIGSEGV.

In the case of multi-thread applications, child thread may not be
available. So if the task is not running, send signal to tgid.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587017022.2275.1063.camel@hbabu-laptop

powerpc/vas: Setup thread IRQ handler per VAS instance

When NX encounters translation error on CRB and any request buffer,
raises an interrupt on the CPU to handle the fault. It can raise one
interrupt for multiple faults. Expects OS to handle these faults and
return credits for fault window after processing faults.

Setup thread IRQ handler and IRQ thread function per each VAS instance.
IRQ handler checks if the thread is already woken up and can handle new
faults. If so returns with IRQ_HANDLED, otherwise wake up thread to
process new faults.

The thread functions reads each CRB entry from fault FIFO until sees
invalid entry. After reading each CRB, determine the corresponding
send window using pswid (from CRB) and process fault CRB. Then
invalidate the entry and return credit. Processing fault CRB and
return credit is described in subsequent patches.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587016982.2275.1060.camel@hbabu-laptop

powerpc/vas: Setup fault window per VAS instance

Setup fault window for each VAS instance. When NX gets a fault on
request buffer, pastes fault CRB in the corresponding fault FIFO and
then raises an interrupt to the OS. The kernel handles this fault
and process faults CRB from this FIFO.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587016846.2275.1053.camel@hbabu-laptop