FAILED: patch "[PATCH] PCI/MSI: Mask MSI-X vectors only on success" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 83dbf898a2d45289be875deb580e93050ba67529 Mon Sep 17 00:00:00 2001
From: Stefan Roese <[email protected]>
Date: Tue, 14 Dec 2021 12:49:32 +0100
Subject: [PATCH] PCI/MSI: Mask MSI-X vectors only on success
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Masking all unused MSI-X entries is done to ensure that a crash kernel starts from a clean slate, which correponds to the reset state of the device as defined in the PCI-E specificion 3.0 and later:

Vector Control for MSI-X Table Entries
--------------------------------------

"00: Mask bit: When this bit is set, the function is prohibited from
sending a message using this MSI-X Table entry.
...
This bit’s state after reset is 1 (entry is masked)."

A Marvell NVME device fails to deliver MSI interrupts after trying to enable MSI-X interrupts due to that masking. It seems to take the MSI-X mask bits into account even when MSI-X is disabled.

While not specification compliant, this can be cured by moving the masking into the success path, so that the MSI-X table entries stay in device reset state when the MSI-X setup fails.

[ tglx: Move it into the success path, add comment and amend changelog ]

index 48e3f4e47b29..6748cf9d7d90 100644
@@ -722,9 +722,6 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 		goto out_disable;
 	}
 
-	/* Ensure that all table entries are masked. */
-	msix_mask_all(base, tsize);
-
 	ret = msix_setup_entries(dev, base, entries, nvec, affd);
 	if (ret)
 		goto out_disable;

@@ -751,6 +748,16 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	/* Set MSI-X enabled bits and unmask the function */
 	pci_intx_for_msi(dev, 0);
 	dev->msix_enabled = 1;
+
+	/*
+	 * Ensure that all table entries are masked to prevent
+	 * stale entries from firing in a crash kernel.
+	 *
+	 * Done late to deal with a broken Marvell NVME device
+	 * which takes the MSI-X mask bits into account even
+	 * when MSI-X is disabled, which prevents MSI delivery.
+	 */
+	msix_mask_all(base, tsize);
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
 
 	pcibios_free_irq(dev);