Re: [PATCH 2/2] PCI: cadence-ep: Fix broken set_msix() callback

[Damien Le Moal <dlemoal@kernel.org>]

On 4/30/25 21:32, Niklas Cassel wrote:
> While the parameter 'interrupts' to the functions pci_epc_set_msi() and
> pci_epc_set_msix() represent the actual number of interrupts, and
> pci_epc_get_msi() and pci_epc_get_msix() return the actual number of
> interrupts.
> 
> These endpoint library functions just mentioned will however supply
> "interrupts - 1" to the EPC callback functions pci_epc_ops->set_msi() and
> pci_epc_ops->set_msix(), and likewise add 1 to return value from
> pci_epc_ops->get_msi() and pci_epc_ops->get_msix(), even though the
> parameter name for the callback function is also named 'interrupts'.
> 
> While the set_msix() callback function in pcie-cadence-ep writes the
> Table Size field correctly (N-1), the calculation of the PBA offset
> is wrong because it calculates space for (N-1) entries instead of N.
> 
> This results in e.g. the following error when using QEMU with PCI
> passthrough on a device which relies on the PCI endpoint subsystem:
> failed to add PCI capability 0x11[0x50]@0xb0: table & pba overlap, or they don't fit in BARs, or don't align
> 
> Fix the calculation of PBA offset in the MSI-X capability.
> 
> Fixes: 3ef5d16f50f8 ("PCI: cadence: Add MSI-X support to Endpoint driver")
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Looks good to me.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

-- 
Damien Le Moal
Western Digital Research