pds_core: Unmask adminq interrupt in work thread

Unmasking the interrupt during the pdsc_adminq_isr
is a bit early and could cause unnecessary interrupts.
Instead always unmask after processing the adminq
and notifyq in pdsc_work_thread()->pdsc_process_adminq().
Also, since we are always unmasking, there's no need
for the local credits variable in pdsc_process_adminq().

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>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

pds_core: Clear BARs on reset

During reset the BARs might be accessed when they are
unmapped. This can cause unexpected issues, so fix it by
clearing the cached BAR values so they are not accessed
until they are re-mapped.

Also, make sure any places that can access the BARs
when they are NULL are prevented.

Fixes: 49ce92fbee0b ("pds_core: add FW update feature to devlink")
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/20240129234035.69802-6-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: Use struct pdsc for the pdsc_adminq_isr private data

The initial design for the adminq interrupt was done based
on client drivers having their own adminq and adminq
interrupt. So, each client driver's adminq isr would use
their specific adminqcq for the private data struct. For the
time being the design has changed to only use a single
adminq for all clients. So, instead use the struct pdsc for
the private data to simplify things a bit.

This also has the benefit of not dereferencing the adminqcq
to access the pdsc struct when the PDSC_S_STOPPING_DRIVER bit
is set and the adminqcq has actually been cleared/freed.

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/20240129234035.69802-4-brett.creeley@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

pds_core: use correct index to mask irq

Use the qcq's interrupt index, not the irq number, to mask
the interrupt. Since the irq number can be out of range from
the number of possible interrupts, we can end up accessing
and potentially scribbling on out-of-range and/or unmapped
memory, making the kernel angry.

[ 3116.039364] BUG: unable to handle page fault for address: ffffbeea1c3edf84
[ 3116.047059] #PF: supervisor write access in kernel mode
[ 3116.052895] #PF: error_code(0x0002) - not-present page
[ 3116.058636] PGD 100000067 P4D 100000067 PUD 1001f2067 PMD 10f82e067 PTE 0
[ 3116.066221] Oops: 0002 [#1] SMP NOPTI
[ 3116.092948] RIP: 0010:iowrite32+0x9/0x76
[ 3116.190452] Call Trace:
[ 3116.193185] <IRQ>
[ 3116.195430] ? show_trace_log_lvl+0x1d6/0x2f9
[ 3116.200298] ? show_trace_log_lvl+0x1d6/0x2f9
[ 3116.205166] ? pdsc_adminq_isr+0x43/0x55 [pds_core]
[ 3116.210618] ? __die_body.cold+0x8/0xa
[ 3116.214806] ? page_fault_oops+0x16d/0x1ac
[ 3116.219382] ? exc_page_fault+0xbe/0x13b
[ 3116.223764] ? asm_exc_page_fault+0x22/0x27
[ 3116.228440] ? iowrite32+0x9/0x76
[ 3116.232143] pdsc_adminq_isr+0x43/0x55 [pds_core]
[ 3116.237627] __handle_irq_event_percpu+0x3a/0x184
[ 3116.243088] handle_irq_event+0x57/0xb0
[ 3116.247575] handle_edge_irq+0x87/0x225
[ 3116.252062] __common_interrupt+0x3e/0xbc
[ 3116.256740] common_interrupt+0x7b/0x98
[ 3116.261216] </IRQ>
[ 3116.263745] <TASK>
[ 3116.266268] asm_common_interrupt+0x22/0x27

Reported-by: Joao Martins <joao.m.martins@oracle.com>
Fixes: 01ba61b55b20 ("pds_core: Add adminq processing and commands")
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20231113183257.71110-2-shannon.nelson@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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: Add adminq processing and commands

Add the service routines for submitting and processing
the adminq messages and for handling notifyq 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>