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

[Jacob Pan]

Hi Nicolin,

On Thu, 13 Feb 2025 13:02:27 -0800
Nicolin Chen <nicolinc@xxxxxxxxxx> wrote:

> 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@xxxxxxxxxx> 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.
> 
It is just confusing that the msg can be IOVA, not always PA as the
comment says. I see it gets deleted anyway in the next patch :)