[PATCH 2/4] nvmet: pci-epf: Do not fall back to using INTX if not supported

[Niklas Cassel]

On Thu, May 08, 2025 at 03:57:43PM +0900, Damien Le Moal wrote:
> Some endpoint PCIe controllers do not support raising legacy INTX
> interrupts. This support is indicated by the intx_capable field of
> struct pci_epc_features. Modify nvmet_pci_epf_raise_irq() to not
> automatically fallback to trying raising an INTX interrupt after an MSI
> or MSI-X error if the controller does not support INTX.
> 
> Fixes: 0faa0fe6f90e ("nvmet: New NVMe PCI endpoint function target driver")
> Cc: stable at vger.kernel.org
> Signed-off-by: Damien Le Moal <dlemoal at kernel.org>

Hm..

0faa0fe6f90e ("nvmet: New NVMe PCI endpoint function target driver") was first
included in v6.14-rc1.

4b313c69a38e ("PCI: endpoint: Add intx_capable to epc_features struct") was first
included in v6.15-rc1.

Perhaps add a:
Cc: stable+noautosel at kernel.org # depends on patch introducing intx_capable flag

So that it is not automatically backported.


> ---
>  drivers/nvme/target/pci-epf.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/nvme/target/pci-epf.c b/drivers/nvme/target/pci-epf.c
> index d5442991f2fb..859953041da8 100644
> --- a/drivers/nvme/target/pci-epf.c
> +++ b/drivers/nvme/target/pci-epf.c
> @@ -636,14 +636,16 @@ static void nvmet_pci_epf_raise_irq(struct nvmet_pci_epf_ctrl *ctrl,
>  	switch (nvme_epf->irq_type) {
>  	case PCI_IRQ_MSIX:
>  	case PCI_IRQ_MSI:
> +		/*
> +		 * If we fail to raise an MSI or MSI-X interrupr, it is likely

s/interrupr/interrupt/


> +		 * because the host is using legacy INTX IRQs (e.g. BIOS,
> +		 * grub). But we can fallback to the INTX type only if the

s/. But/, but/


> +		 * endpoint controller supports this type.
> +		 */
>  		ret = pci_epc_raise_irq(epf->epc, epf->func_no, epf->vfunc_no,
>  					nvme_epf->irq_type, cq->vector + 1);
> -		if (!ret)
> +		if (!ret || !nvme_epf->epc_features->intx_capable)
>  			break;
> -		/*
> -		 * If we got an error, it is likely because the host is using
> -		 * legacy IRQs (e.g. BIOS, grub).
> -		 */
>  		fallthrough;
>  	case PCI_IRQ_INTX:
>  		ret = pci_epc_raise_irq(epf->epc, epf->func_no, epf->vfunc_no,
> -- 
> 2.49.0
> 
>