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    Subject[PATCH 5.15 120/177] PCI/MSI: Mask MSI-X vectors only on success
    Date
    From: Stefan Roese <sr@denx.de>

    commit 83dbf898a2d45289be875deb580e93050ba67529 upstream.

    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
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/pci/msi.c | 13 ++++++++++---
    1 file changed, 10 insertions(+), 3 deletions(-)

    --- a/drivers/pci/msi.c
    +++ b/drivers/pci/msi.c
    @@ -721,9 +721,6 @@ static int msix_capability_init(struct p
    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;
    @@ -750,6 +747,16 @@ static int msix_capability_init(struct p
    /* 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);

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