habanalabs: fix nullifying of destroyed mmu pgt pool

BugLink: https://bugs.launchpad.net/bugs/1949397

[ Upstream commit 89aad77 ]

In case of host-resident MMU, when the page tables pool is destroyed,
its pointer is not nullified correctly.
As a result, on a device fini which happens after a failing reset, the
already destroyed pool is accessed, which leads to a kernel panic.
The patch fixes the setting of the pool pointer to NULL.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

Author: Tomer Tayar

drivers/misc/habanalabs/common/mmu_v1.c

@@ -470,13 +470,13 @@ static void hl_mmu_v1_fini(struct hl_device *hdev)
 	if (!ZERO_OR_NULL_PTR(hdev->mmu_priv.hr.mmu_shadow_hop0)) {
 		kvfree(hdev->mmu_priv.dr.mmu_shadow_hop0);
 		gen_pool_destroy(hdev->mmu_priv.dr.mmu_pgt_pool);
-	}
 
-	/* Make sure that if we arrive here again without init was called we
-	 * won't cause kernel panic. This can happen for example if we fail
-	 * during hard reset code at certain points
-	 */
-	hdev->mmu_priv.dr.mmu_shadow_hop0 = NULL;
+		/* Make sure that if we arrive here again without init was
+		 * called we won't cause kernel panic. This can happen for
+		 * example if we fail during hard reset code at certain points
+		 */
+		hdev->mmu_priv.dr.mmu_shadow_hop0 = NULL;
+	}
 }
 
 /**