linux-kernel - [PATCH 3/3] bus: mhi: pci-generic: Fix hibernation

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Date:   Sun,  6 Jun 2021 21:07:41 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     hemantk@...eaurora.org, bbhatt@...eaurora.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        jarvis.w.jiang@...il.com, loic.poulain@...aro.org,
        Shujun Wang <wsj20369@....com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH 3/3] bus: mhi: pci-generic: Fix hibernation

From: Loic Poulain <loic.poulain@...aro.org>

This patch fixes crash after resuming from hibernation. The issue
occurs when mhi stack is builtin and so part of the 'restore-kernel',
causing the device to be resumed from 'restored kernel' with a no
more valid context (memory mappings etc...) and leading to spurious
crashes.

This patch fixes the issue by implementing proper freeze/restore
callbacks.

Reported-by: Shujun Wang <wsj20369@....com>
Signed-off-by: Loic Poulain <loic.poulain@...aro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Link: https://lore.kernel.org/r/1622571445-4505-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/bus/mhi/pci_generic.c | 36 ++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
index 0a6619ad292c..b3357a8a2fdb 100644
--- a/drivers/bus/mhi/pci_generic.c
+++ b/drivers/bus/mhi/pci_generic.c
@@ -935,9 +935,43 @@ static int __maybe_unused mhi_pci_resume(struct device *dev)
 	return ret;
 }
 
+static int __maybe_unused mhi_pci_freeze(struct device *dev)
+{
+	struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
+	struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
+
+	/* We want to stop all operations, hibernation does not guarantee that
+	 * device will be in the same state as before freezing, especially if
+	 * the intermediate restore kernel reinitializes MHI device with new
+	 * context.
+	 */
+	if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
+		mhi_power_down(mhi_cntrl, false);
+		mhi_unprepare_after_power_down(mhi_cntrl);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused mhi_pci_restore(struct device *dev)
+{
+	struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
+
+	/* Reinitialize the device */
+	queue_work(system_long_wq, &mhi_pdev->recovery_work);
+
+	return 0;
+}
+
 static const struct dev_pm_ops mhi_pci_pm_ops = {
 	SET_RUNTIME_PM_OPS(mhi_pci_runtime_suspend, mhi_pci_runtime_resume, NULL)
-	SET_SYSTEM_SLEEP_PM_OPS(mhi_pci_suspend, mhi_pci_resume)
+#ifdef CONFIG_PM_SLEEP
+	.suspend = mhi_pci_suspend,
+	.resume = mhi_pci_resume,
+	.freeze = mhi_pci_freeze,
+	.thaw = mhi_pci_restore,
+	.restore = mhi_pci_restore,
+#endif
 };
 
 static struct pci_driver mhi_pci_driver = {
-- 
2.25.1