Re: [PATCH] ahci: force 32-bit DMA for JMicron JMB582/JMB585

[Niklas Cassel <cassel@kernel.org>]

On Fri, Sep 04, 2026 at 07:38:06AM -0500, Mario Limonciello wrote:
> On 9/4/26 06:14, Niklas Cassel wrote:
> > 
> > 2) A fix for the AMD IOMMU driver to be merged, and backported to stable,
> > such that us writing a fix that drops the 32-bit only DMA quirk for JMicron
> > JMB582/585, which when backported to stable, will not cause users with an
> > AMD IOMMU to silently get their filesystem corrupted.
> > 
> > 
> 
> Right now what I'm thinking of doing is a quirk in arch/x86/pci/fixup.c to
> set the registers that could influence this issue.
> 
> An alternative may be some quirks to the AMD IOMMU driver to avoid using the
> upper 5 bits for the IOVA allocations (making it 59 bit).

No stress with regards to JMB582/585. We will keep the quirk as long as it
is needed to avoid the AMD IOMMU issue, but please CC me if you send out a
fix.

It is probably worse for those like Mikael Etienne, who is using an AMD 600
Series Chipset SATA Controller [1022:43f6], since for those SATA controllers,
we do not have a 32-bit only quirk that hides/workarounds the problem.


Kind regards,
Niklas