[PATCH v2] octeontx2-af: Fix PF driver crash with kexec kernel booting

[Anshumali Gaur <agaur@marvell.com>]

During a kexec reboot the hardware is not power-cycled, so AF state from
the old kernel can persist into the new kernel. When AF and PF drivers
are built as modules, the PF driver may probe before AF reinitializes
the hardware.

The PF driver treats the RVUM block revision as an indication that AF
initialization is complete. If this value is left uncleared at shutdown,
PF may incorrectly assume AF is ready and access stale hardware state,
leading to a crash.

Clear the RVUM block revision during AF shutdown to avoid PF
mis-detecting AF readiness after kexec.

Fixes: 54494aa5d1e6 ("octeontx2-af: Add Marvell OcteonTX2 RVU AF driver")
Signed-off-by: Anshumali Gaur <agaur@marvell.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> (1)

(1) https://lore.kernel.org/all/89011ab8-0ec2-431d-8842-f3738870db36@intel.com/
---
v2:
  - Update commit message
  - Add Reviewed-by
 drivers/net/ethernet/marvell/octeontx2/af/rvu.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
index 747fbdf2a908..8530df8b3fda 100644
--- a/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
+++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu.c
@@ -3632,11 +3632,22 @@ static void rvu_remove(struct pci_dev *pdev)
 	devm_kfree(&pdev->dev, rvu);
 }
 
+static void rvu_shutdown(struct pci_dev *pdev)
+{
+	struct rvu *rvu = pci_get_drvdata(pdev);
+
+	if (!rvu)
+		return;
+
+	rvu_clear_rvum_blk_revid(rvu);
+}
+
 static struct pci_driver rvu_driver = {
 	.name = DRV_NAME,
 	.id_table = rvu_id_table,
 	.probe = rvu_probe,
 	.remove = rvu_remove,
+	.shutdown = rvu_shutdown,
 };
 
 static int __init rvu_init_module(void)
-- 
2.25.1