Re: [PATCH] PCI: vmd: Assign vmd irq domain before enumeration

["Patel, Nirmal" <nirmal.patel@linux.intel.com>]

On 2/23/2022 12:52 AM, Nirmal Patel wrote:
> vmd creates and assigns separate irq domain only when MSI remapping is
> enabled. For example VMD-MSI. But vmd doesn't assign irq domain when
> MSI remapping is disabled resulting child devices getting default
> PCI-MSI irq domain. Now when Interrupt remapping is enabled all the
> pci devices are assigned INTEL-IR-MSI domain including vmd endpoints.
> But devices behind vmd gets PCI-MSI irq domain when vmd creates root
> bus and configures child devices.
>
> As a result DMAR errors were observed when interrupt remapping was
> enabled on Intel Icelake CPUs.
> For instance:
> DMAR: DRHD: handling fault status reg 2
> DMAR: [INTR-REMAP] Request device [0xe2:0x00.0] fault index 0xa00
> [fault reason 0x25] Blocked a compatibility format interrupt request
>
> So make sure vmd assigns proper irq domain. This patch also removes
> a placeholder patch 2565e5b69c44 (PCI: vmd: Do not disable MSI-X
> remapping if interrupt remapping is enabled by IOMMU.) MSI remapping
> should be enabled or disabled with and without Interrupt remap.
>
> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
> ---
>  drivers/pci/controller/vmd.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index cc166c683638..c8d73d75a1c0 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -813,8 +813,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  	 * acceptable because the guest is usually CPU-limited and MSI
>  	 * remapping doesn't become a performance bottleneck.
>  	 */
> -	if (iommu_capable(vmd->dev->dev.bus, IOMMU_CAP_INTR_REMAP) ||
> -	    !(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
> +	if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
>  	    offset[0] || offset[1]) {
>  		ret = vmd_alloc_irqs(vmd);
>  		if (ret)
> @@ -853,7 +852,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>  	vmd_attach_resources(vmd);
>  	if (vmd->irq_domain)
>  		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
> -
> +	else
> +		dev_set_msi_domain(&vmd->bus->dev, vmd->dev->dev.msi.domain);
> +	
>  	vmd_acpi_begin();
>  
>  	pci_scan_child_bus(vmd->bus);

Gentle ping!

Thanks

nirmal