Last year, the code that manages GSI channel transactions switched
from using spinlock-protected linked lists to using indexes into the
ring buffer used for a channel.  Recently, Google reported seeing
transaction reference count underflows occasionally during shutdown.

Doug Anderson found a way to reproduce the issue reliably, and
bisected the issue to the commit that eliminated the linked lists
and the lock.  The root cause was ultimately determined to be
related to unused transactions being committed as part of the modem
shutdown cleanup activity.  Unused transactions are not normally
expected (except in error cases).

The modem uses some ranges of IPA-resident memory, and whenever it
shuts down we zero those ranges.  In ipa_filter_reset_table() a
transaction is allocated to zero modem filter table entries.  If
hashing is not supported, hashed table memory should not be zeroed.
But currently nothing prevents that, and the result is an unused
transaction.  Something similar occurs when we zero routing table
entries for the modem.

By preventing any attempt to clear hashed tables when hashing is not
supported, the reference count underflow is avoided in this case.

Note that there likely remains an issue with properly freeing unused
transactions (if they occur due to errors).  This patch addresses
only the underflows that Google originally reported.

Cc: <stable@vger.kernel.org> # 6.1.x
Fixes: d338ae28d8a8 ("net: ipa: kill all other transaction lists")
Tested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20230724224055.1688854-1-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

IPA_STATUS_SIZE was introduced in commit b8dc7d0eea5a as a replacement
for the size of the removed struct ipa_status which had size
sizeof(__le32[8]). Use this value as IPA_STATUS_SIZE.

Fixes: b8dc7d0eea5a ("net: ipa: stop using sizeof(status)")
Signed-off-by: Bert Karwatzki <spasswolf@web.de>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230531103618.102608-1-spasswolf@web.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Conflicts:

drivers/net/ethernet/mediatek/mtk_ppe.c
  3fbe4d8c0e53 ("net: ethernet: mtk_eth_soc: ppe: add support for flow accounting")
  924531326e2d ("net: ethernet: mtk_eth_soc: add missing ppe cache flush when deleting a flow")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

In gsi_trans_pool_init_dma(), the total size of a pool of memory
used for DMA transactions is calculated.  However the calculation is
done incorrectly.

For 4KB pages, this total size is currently always more than one
page, and as a result, the calculation produces a positive (though
incorrect) total size.  The code still works in this case; we just
end up with fewer DMA pool entries than we intended.

Bjorn Andersson tested booting a kernel with 16KB pages, and hit a
null pointer derereference in sg_alloc_append_table_from_pages(),
descending from gsi_trans_pool_init_dma().  The cause of this was
that a 16KB total size was going to be allocated, and with 16KB
pages the order of that allocation is 0.  The total_size calculation
yielded 0, which eventually led to the crash.

Correcting the total_size calculation fixes the problem.

Reported-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Tested-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Fixes: 9dd441e4ed57 ("soc: qcom: ipa: GSI transactions")
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20230328162751.2861791-1-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

In the IPA device sysfs directory, the "version" file can be read to
find out what IPA version is implemented.  The content of this file
is supplied by ipa_version_string(), which needs to be updated to
properly handle IPA v5.0.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230322144742.2203947-1-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add the configuration data required for IPA v5.0, which is used in
the SDX65 SoC.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add the definitions of GSI register offsets and fields for IPA v5.0.
These are used for the SDX65 SoC.  Increase the maximum channel and
event ring counts supported by the driver, so those implemented by
the SDX65 are supported.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add the definitions of IPA register offsets and fields for IPA v5.0.
These are used for the SDX65 SoC.

In the Makefile, split IPA_VERSIONS to use IPA_REG_VERSIONS and
IPA_DATA_VERSIONS instead, to allow IPA register definitions for a
new version to be added separate from the IPA data.

Rename GSI_IPA_VERSIONS to be GSI_REG_VERSIONS for consistency.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

A recent commit defined HW_PARAM_4 as a GSI register ID but did not
add it to gsi_reg_id_valid() to indicate it's valid (for IPA v5.0+).
Add version checks for the HW_PARAM_2 and INTER_EE IRQ GSI registers
there as well.

IPA v5.0 supports up to 8 source and destination resource groups.
Update the validity check (and the comments where the register IDs
are defined) to reflect that.  Similarly update comments and
validity checks for the hash/cache-related registers.

Note that this patch fixes an omission and constrains things
further, but these don't technically represent bugs.

Fixes: f651334e1ef5 ("net: ipa: add HW_PARAM_4 GSI register")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

A recent commit defined a few IPA registers used for IPA v5.0+.
One of those was a mistake.  Although the filter and router caches
get *flushed* using a single register, they use distinct registers
(ENDP_FILTER_CACHE_CFG and ENDP_ROUTER_CACHE_CFG) for configuration.

And although there *exists* a FILT_ROUT_CACHE_CFG register, it is
not needed in upstream code.  So get rid of definitions related to
FILT_ROUT_CACHE_CFG, because they are not needed.

Fixes: 8ba59716d16a ("net: ipa: define IPA v5.0+ registers")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>