Re: [PATCH 5.10 392/530] iommu/vt-d: Preset Access/Dirty bits for IOVA over FL

[Sasha Levin]

On Mon, May 17, 2021 at 10:38:42AM +0800, Lu Baolu wrote:
> Hi Wolfgang,
>
> On 5/15/21 9:28 PM, Wolfgang Müller wrote:
> > Hi!
> >
> > First of all, apologies if this is the wrong place to post a problem
> > report. I figured since I was going to reference a particular commit
> > anyway I might as well reply to the patch series that (seemed to have)
> > introduced the problem.
> >
> > > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > >
> > > [ Upstream commit a8ce9ebbecdfda3322bbcece6b3b25888217f8e3 ]
> > >
> > > The Access/Dirty bits in the first level page table entry will be set
> > > whenever a page table entry was used for address translation or write
> > > permission was successfully translated. This is always true when using
> > > the first-level page table for kernel IOVA. Instead of wasting hardware
> > > cycles to update the certain bits, it's better to set them up at the
> > > beginning.
> >
> > This commit seems to trigger a kernel panic very early in boot for me in
> > 5.10.37 (36 is fine):
>
> It seems due to the back-ported patch:
>
> -	if (!sg) {
> -		sg_res = nr_pages;
> -		pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | attr;
> +		if (domain->domain.type == IOMMU_DOMAIN_DMA) {
> +			attr |= DMA_FL_PTE_ACCESS;
> +			if (prot & DMA_PTE_WRITE)
> +				attr |= DMA_FL_PTE_DIRTY;
> +		}
> 	}
>
> +	pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | attr;
>
> Greg, do you want me to rework this patch, or submit an incremental fix?

Could you send a reworked patch please?

--
Thanks,
Sasha