[PATCH 5.4 014/184] scsi: mpt3sas: Block PCI config access from userspace during reset

[Greg Kroah-Hartman]

From: Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx>

commit 3c8604691d2acc7b7d4795d9695070de9eaa5828 upstream.

While diag reset is in progress there is short duration where all access to
controller's PCI config space from the host needs to be blocked. This is
due to a hardware limitation of the IOC controllers.

Block all access to controller's config space from userland applications by
calling pci_cfg_access_lock() while diag reset is in progress and unlocking
it again after the controller comes back to ready state.

Link: https://lore.kernel.org/r/20210330105137.20728-1-sreekanth.reddy@xxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx #v5.4.108+
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/scsi/mpt3sas/mpt3sas_base.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -6572,6 +6572,8 @@ _base_diag_reset(struct MPT3SAS_ADAPTER
 
 	ioc_info(ioc, "sending diag reset !!\n");
 
+	pci_cfg_access_lock(ioc->pdev);
+
 	drsprintk(ioc, ioc_info(ioc, "clear interrupts\n"));
 
 	count = 0;
@@ -6653,10 +6655,12 @@ _base_diag_reset(struct MPT3SAS_ADAPTER
 		goto out;
 	}
 
+	pci_cfg_access_unlock(ioc->pdev);
 	ioc_info(ioc, "diag reset: SUCCESS\n");
 	return 0;
 
  out:
+	pci_cfg_access_unlock(ioc->pdev);
 	ioc_err(ioc, "diag reset: FAILED\n");
 	return -EFAULT;
 }