Patch "powerpc/eeh: Restore initial state in eeh_pe_reset_and_recover()" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/eeh: Restore initial state in eeh_pe_reset_and_recover()

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-eeh-restore-initial-state-in-eeh_pe_reset_and_recover.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Gavin Shan <[email protected]>
Date: Wed, 27 Apr 2016 11:14:51 +1000
Subject: powerpc/eeh: Restore initial state in eeh_pe_reset_and_recover()

From: Gavin Shan <[email protected]>

commit 5a0cdbfd17b90a89c64a71d8aec9773ecdb20d0d upstream.

The function eeh_pe_reset_and_recover() is used to recover EEH error when the passthrou device are transferred to guest and backwards. The content in the device's config space will be lost on PE reset issued in the middle of the recovery. The function saves/restores it before/after the reset. However, config access to some adapters like Broadcom BCM5719 at this point will causes fenced PHB. The config space is always blocked and we save 0xFF's that are restored at late point. The memory BARs are totally corrupted, causing another EEH error upon access to one of the memory BARs.

This restores the config space on those adapters like BCM5719 from the content saved to the EEH device when it's populated, to resolve above issue.

---
 arch/powerpc/kernel/eeh_driver.c |   23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

@@ -171,6 +171,16 @@ static void *eeh_dev_save_state(void *da
 	if (!edev)
 		return NULL;
 
+	/*
+	 * We cannot access the config space on some adapters.
+	 * Otherwise, it will cause fenced PHB. We don't save
+	 * the content in their config space and will restore
+	 * from the initial config space saved when the EEH
+	 * device is created.
+	 */
+	if (edev->pe && (edev->pe->state & EEH_PE_CFG_RESTRICTED))
+		return NULL;
+
 	pdev = eeh_dev_to_pci_dev(edev);
 	if (!pdev)
 		return NULL;

@@ -312,6 +322,19 @@ static void *eeh_dev_restore_state(void
 	if (!edev)
 		return NULL;
 
+	/*
+	 * The content in the config space isn't saved because
+	 * the blocked config space on some adapters. We have
+	 * to restore the initial saved config space when the
+	 * EEH device is created.
+	 */
+	if (edev->pe && (edev->pe->state & EEH_PE_CFG_RESTRICTED)) {
+		if (list_is_last(&edev->list, &edev->pe->edevs))
+			eeh_pe_restore_bars(edev->pe);
+
+		return NULL;
+	}
+
 	pdev = eeh_dev_to_pci_dev(edev);
 	if (!pdev)
 		return NULL;

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/powerpc-eeh-restore-initial-state-in-eeh_pe_reset_and_recover.patch queue-4.6/revert-powerpc-eeh-fix-crash-in-eeh_add_device_early-on-cell.patch queue-4.6/powerpc-eeh-don-t-report-error-in-eeh_pe_reset_and_recover.patch