Re: [PATCH] PCI: dwc: ep: Fix regression in dw_pcie_ep_raise_msi_irq()

[Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>]

On Feb 10, 2026 / 19:12, Niklas Cassel wrote:
> When using the nvmet-pci-epf EPF driver, and starting the EP before
> starting a host with UEFI, the UEFI performs NVMe commands e.g.
> Identify Controller, to get the name of the controller.
> 
> nvmet-pci-epf will post the CQE (completion queue entry) to the Admin
> Completion Queue, and then raise an IRQ (using
> dw_pcie_ep_raise_msi_irq()).
> 
> Once the host boots Linux, we will see a WARN_ON_ONCE() from
> dw_pcie_ep_raise_msi_irq(), and then the booting of the host hangs,
> because it never gets an IRQ when loading the nvme driver.
> 
> The reason is that the MSI target address used by UEFI and Linux might
> be different, which will cause dw_pcie_ep_raise_msi_irq() to simply
> return -EINVAL.
> 
> This was working before commit 8719c64e76bf ("PCI: dwc: ep: Cache MSI
> outbound iATU mapping"), so this is a regression.
> 
> Also, remove the warning, as we cannot know if there are operations in
> flight or not, so it seems wrong to print this warning unconditionally
> at every boot when e.g. nvmet-pci-epf is used with a host with UEFI.
> 
> Fixes: 8719c64e76bf ("PCI: dwc: ep: Cache MSI outbound iATU mapping")
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Niklas, thank you for the fix. I confirmed that this patch avoids the
"WARN_ON_ONCE() from dw_pcie_ep_raise_msi_irq()" and the host hangs in
my environment.

Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>