PCI/MSI: Mask MSI-X vectors only on success

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 ]

Fixes: aa8092c1d1f1 ("PCI/MSI: Mask all unused MSI-X entries")
Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-pci@vger.kernel.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Marek Vasut <marex@denx.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211210161025.3287927-1-sr@denx.de

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 48e3f4e47b293c94fd3b45fa14121e72f81d9002..6748cf9d7d90bd1e53ae0c532d63471d43bb7cab 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -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);