PCI: dwc: ep: Refresh MSI Message Address cache on change

PCI: dwc: ep: Refresh MSI Message Address cache on change

Endpoint drivers use dw_pcie_ep_raise_msi_irq() to raise MSI interrupts to
the host.  After 8719c64e76bf ("PCI: dwc: ep: Cache MSI outbound iATU
mapping"), dw_pcie_ep_raise_msi_irq() caches the Message Address from the
MSI Capability in ep->msi_msg_addr.  But that Message Address is controlled
by the host, and it may change.  For example, if:

  - firmware on the host configures the Message Address and triggers an
    MSI,

  - a driver on the Endpoint raises the MSI via dw_pcie_ep_raise_msi_irq(),
    which caches the Message Address,

  - a kernel on the host reconfigures the Message Address and the host
    kernel driver triggers another MSI,

dw_pcie_ep_raise_msi_irq() notices that the Message Address no longer
matches the cached ep->msi_msg_addr, warns about it, and returns error
instead of raising the MSI.  The host kernel may hang because it never
receives the MSI.

This was seen with the nvmet_pci_epf_driver: the host UEFI performs NVMe
commands, e.g. Identify Controller to get the name of the controller,
nvmet-pci-epf posts the completion queue entry and raises an IRQ using
dw_pcie_ep_raise_msi_irq().  When the host boots Linux, we see a
WARN_ON_ONCE() from dw_pcie_ep_raise_msi_irq(), and the host kernel hangs
because the nvme driver never gets an IRQ.

Remove the warning when dw_pcie_ep_raise_msi_irq() notices that Message
Address has changed, remap using the new address, and update the
ep->msi_msg_addr cache.

Fixes: 8719c64e76bf ("PCI: dwc: ep: Cache MSI outbound iATU mapping")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Acked-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20260210181225.3926165-2-cassel@kernel.org