pds_core: Fix pdsc_check_pci_health function to use work thread

When the driver notices fw_status == 0xff it tries to perform a PCI
reset on itself via pci_reset_function() in the context of the driver's
health thread. However, pdsc_reset_prepare calls
pdsc_stop_health_thread(), which attempts to stop/flush the health
thread. This results in a deadlock because the stop/flush will never
complete since the driver called pci_reset_function() from the health
thread context. Fix by changing the pdsc_check_pci_health_function()
to queue a newly introduced pdsc_pci_reset_thread() on the pdsc's
work queue.

Unloading the driver in the fw_down/dead state uncovered another issue,
which can be seen in the following trace:

WARNING: CPU: 51 PID: 6914 at kernel/workqueue.c:1450 __queue_work+0x358/0x440
[...]
RIP: 0010:__queue_work+0x358/0x440
[...]
Call Trace:
<TASK>
? __warn+0x85/0x140
? __queue_work+0x358/0x440
? report_bug+0xfc/0x1e0
? handle_bug+0x3f/0x70
? exc_invalid_op+0x17/0x70
? asm_exc_invalid_op+0x1a/0x20
? __queue_work+0x358/0x440
queue_work_on+0x28/0x30
pdsc_devcmd_locked+0x96/0xe0 [pds_core]
pdsc_devcmd_reset+0x71/0xb0 [pds_core]
pdsc_teardown+0x51/0xe0 [pds_core]
pdsc_remove+0x106/0x200 [pds_core]
pci_device_remove+0x37/0xc0
device_release_driver_internal+0xae/0x140
driver_detach+0x48/0x90
bus_remove_driver+0x6d/0xf0
pci_unregister_driver+0x2e/0xa0
pdsc_cleanup_module+0x10/0x780 [pds_core]
__x64_sys_delete_module+0x142/0x2b0
? syscall_trace_enter.isra.18+0x126/0x1a0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7fbd9d03a14b
[...]

Fix this by preventing the devcmd reset if the FW is not running.

Fixes: d9407ff11809 ("pds_core: Prevent health thread from running during reset/remove")
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: use pci_reset_function for health reset

We get the benefit of all the PCI reset locking and recovery if
we use the existing pci_reset_function() that will call our
local reset handlers.

Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: Clean up init/uninit flows to be more readable

The setup and teardown flows are somewhat hard to follow regarding
pdsc_core_init()/pdsc_dev_init() and their corresponding teardown
flows being in pdsc_teardown(). Improve the readability by adding
new pdsc_core_uninit()/pdsc_dev_unint() functions that mirror their
init counterparts. Also, move the notify and admin qcq allocations
into pdsc_core_init(), so they can be freed in pdsc_core_uninit().

Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

pds_core: Rework teardown/setup flow to be more common

Currently the teardown/setup flow for driver probe/remove is quite
a bit different from the reset flows in pdsc_fw_down()/pdsc_fw_up().
One key piece that's missing are the calls to pci_alloc_irq_vectors()
and pci_free_irq_vectors(). The pcie reset case is calling
pci_free_irq_vectors() on reset_prepare, but not calling the
corresponding pci_alloc_irq_vectors() on reset_done. This is causing
unexpected/unwanted interrupt behavior due to the adminq interrupt
being accidentally put into legacy interrupt mode. Also, the
pci_alloc_irq_vectors()/pci_free_irq_vectors() functions are being
called directly in probe/remove respectively.

Fix this inconsistency by making the following changes:
1. Always call pdsc_dev_init() in pdsc_setup(), which calls
pci_alloc_irq_vectors() and get rid of the now unused
pds_dev_reinit().
2. Always free/clear the pdsc->intr_info in pdsc_teardown()
since this structure will get re-alloced in pdsc_setup().
3. Move the calls of pci_free_irq_vectors() to pdsc_teardown()
since pci_alloc_irq_vectors() will always be called in
pdsc_setup()->pdsc_dev_init() for both the probe/remove and
reset flows.
4. Make sure to only create the debugfs "identity" entry when it
doesn't already exist, which it will in the reset case because
it's already been created in the initial call to pdsc_dev_init().

Fixes: ffa55858330f ("pds_core: implement pci reset handlers")
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20240129234035.69802-7-brett.creeley@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

pds_core: Prevent race issues involving the adminq

There are multiple paths that can result in using the pdsc's
adminq.

[1] pdsc_adminq_isr and the resulting work from queue_work(),
i.e. pdsc_work_thread()->pdsc_process_adminq()

[2] pdsc_adminq_post()

When the device goes through reset via PCIe reset and/or
a fw_down/fw_up cycle due to bad PCIe state or bad device
state the adminq is destroyed and recreated.

A NULL pointer dereference can happen if [1] or [2] happens
after the adminq is already destroyed.

In order to fix this, add some further state checks and
implement reference counting for adminq uses. Reference
counting was used because multiple threads can attempt to
access the adminq at the same time via [1] or [2]. Additionally,
multiple clients (i.e. pds-vfio-pci) can be using [2]
at the same time.

The adminq_refcnt is initialized to 1 when the adminq has been
allocated and is ready to use. Users/clients of the adminq
(i.e. [1] and [2]) will increment the refcnt when they are using
the adminq. When the driver goes into a fw_down cycle it will
set the PDSC_S_FW_DEAD bit and then wait for the adminq_refcnt
to hit 1. Setting the PDSC_S_FW_DEAD before waiting will prevent
any further adminq_refcnt increments. Waiting for the
adminq_refcnt to hit 1 allows for any current users of the adminq
to finish before the driver frees the adminq. Once the
adminq_refcnt hits 1 the driver clears the refcnt to signify that
the adminq is deleted and cannot be used. On the fw_up cycle the
driver will once again initialize the adminq_refcnt to 1 allowing
the adminq to be used again.

Fixes: 01ba61b55b20 ("pds_core: Add adminq processing and commands")
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://lore.kernel.org/r/20240129234035.69802-5-brett.creeley@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

pds_core: fix up some format-truncation complaints

Our friendly kernel test robot pointed out a couple of potential
string truncation issues. None of which were we worried about,
but can be relatively easily fixed to quiet the complaints.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310211736.66syyDpp-lkp@intel.com/
Fixes: 45d76f492938 ("pds_core: set up device and adminq")
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20231113183257.71110-3-shannon.nelson@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

pds_core: add attempts to fix broken PCI

If we see a 0xff value from a PCI register read, we know that
the PCI connection is broken, possibly by a low level reset that
didn't go through the nice pci_error_handlers path.

Make use of the PCI cleanup code that we already have from the
reset handlers and add some detection and attempted recovery
from a broken PCI connection.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: implement pci reset handlers

Implement the callbacks for a nice PCI reset. These get called
when a user is nice enough to use the sysfs PCI reset entry, e.g.
echo 1 > /sys/bus/pci/devices/0000:2b:00.0/reset

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: publish events to the clients

When the Core device gets an event from the device, or notices
the device FW to be up or down, it needs to send those events
on to the clients that have an event handler. Add the code to
pass along the events to the clients.

The entry points pdsc_register_notify() and pdsc_unregister_notify()
are EXPORTed for other drivers that want to listen for these events.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: devlink params for enabling VIF support

Add the devlink parameter switches so the user can enable
the features supported by the VFs. The only feature supported
at the moment is vDPA.

Example:
devlink dev param set pci/0000:2b:00.0 \
name enable_vnet cmode runtime value true

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: add auxiliary_bus devices

An auxiliary_bus device is created for each vDPA type VF at VF
probe and destroyed at VF remove. The aux device name comes
from the driver name + VIF type + the unique id assigned at PCI
probe. The VFs are always removed on PF remove, so there should
be no issues with VFs trying to access missing PF structures.

The auxiliary_device names will look like "pds_core.vDPA.nn"
where 'nn' is the VF's uid.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: add initial VF device handling

This is the initial VF PCI driver framework for the new
pds_vdpa VF device, which will work in conjunction with an
auxiliary_bus client of the pds_core driver. This does the
very basics of registering for the new VF device, setting
up debugfs entries, and registering with devlink.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: set up the VIF definitions and defaults

The Virtual Interfaces (VIFs) supported by the DSC's
configuration (vDPA, Eth, RDMA, etc) are reported in the
dev_ident struct and made visible in debugfs. At this point
only vDPA is supported in this driver so we only setup
devices for that feature.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: add FW update feature to devlink

Add in the support for doing firmware updates. Of the two
main banks available, a and b, this updates the one not in
use and then selects it for the next boot.

Example:
devlink dev flash pci/0000:b2:00.0 \
file pensando/dsc_fw_1.63.0-22.tar

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: set up device and adminq

Set up the basic adminq and notifyq queue structures. These are
used mostly by the client drivers for feature configuration.
These are essentially the same adminq and notifyq as in the
ionic driver.

Part of this includes querying for device identity and FW
information, so we can make that available to devlink dev info.

$ devlink dev info pci/0000:b5:00.0
pci/0000:b5:00.0:
driver pds_core
serial_number FLM18420073
versions:
fixed:
asic.id 0x0
asic.rev 0x0
running:
fw 1.51.0-73
stored:
fw.goldfw 1.15.9-C-22
fw.mainfwa 1.60.0-73
fw.mainfwb 1.60.0-57

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: add devlink health facilities

Add devlink health reporting on top of our fw watchdog.

Example:
# devlink health show pci/0000:2b:00.0 reporter fw
pci/0000:2b:00.0:
reporter fw
state healthy error 0 recover 0
# devlink health diagnose pci/0000:2b:00.0 reporter fw
Status: healthy State: 1 Generation: 0 Recoveries: 0

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: health timer and workqueue

Add in the periodic health check and the related workqueue,
as well as the handlers for when a FW reset is seen.

The firmware is polled every 5 seconds to be sure that it is
still alive and that the FW generation didn't change.

The alive check looks to see that the PCI bus is still readable
and the fw_status still has the RUNNING bit on. If not alive,
the driver stops activity and tears things down. When the FW
recovers and the alive check again succeeds, the driver sets
back up for activity.

The generation check looks at the fw_generation to see if it
has changed, which can happen if the FW crashed and recovered
or was updated in between health checks. If changed, the
driver counts that as though the alive test failed and forces
the fw_down/fw_up cycle.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: add devcmd device interfaces

The devcmd interface is the basic connection to the device through the
PCI BAR for low level identification and command services. This does
the early device initialization and finds the identity data, and adds
devcmd routines to be used by later driver bits.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pds_core: initial framework for pds_core PF driver

This is the initial PCI driver framework for the new pds_core device
driver and its family of devices. This does the very basics of
registering for the new PF PCI device 1dd8:100c, setting up debugfs
entries, and registering with devlink.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>