Re: [PATCH v1 01/13] genirq/msi: Store the IOMMU IOVA directly in msi_desc instead of iommu_cookie

On Thu, Feb 13, 2025 at 12:28:49PM -0800, Jacob Pan wrote:

Hi Nicolin,

On Sat, 8 Feb 2025 01:02:34 -0800 Nicolin Chen nicolinc@nvidia.com wrote:

...

-static inline void msi_desc_set_iommu_cookie(struct msi_desc *desc,

• 			     const void
  

*iommu_cookie) +/**

• • iommu_dma_compose_msi_msg() - Apply translation to an MSI message
• • @desc: MSI descriptor prepared by iommu_dma_prepare_msi()
• • @msg: MSI message containing target physical address
• */

Is it IOVA not PA?

This is moved from dma-iommu.c so we didn't change that.

And I think it's correct to say "target physical address" as the irqchip driver does pass in a PA via @msg.

Then iommu_dma_compose_msi_msg() kind of reverse-translates that, overwriting the msg with the "IOVA" from @desc.

Thanks Nicolin

...

+static inline void iommu_dma_compose_msi_msg(struct msi_desc *desc,

• 			     struct msi_msg *msg)
  

{ -} +#ifdef CONFIG_IRQ_MSI_IOMMU

• if (desc->iommu_msi_page_shift) {

• u64 msi_iova = desc->iommu_msi_iova
  

• 	       << desc->iommu_msi_page_shift;
  

• msg->address_hi = upper_32_bits(msi_iova);
  

• msg->address_lo = lower_32_bits(msi_iova) |
  

• 		  (msg->address_lo &
  

• 		   ((1 <<
  

desc->iommu_msi_page_shift) - 1));

• }

#endif +}