From: Jason Gunthorpe <jgg@nvidia.com>
To: Vasant Hegde <vasant.hegde@amd.com>
Cc: Ankit Soni <Ankit.Soni@amd.com>,
iommu@lists.linux.dev, suravee.suthikulpanit@amd.com,
joro@8bytes.org, will@kernel.org, robin.murphy@arm.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] iommu/amd: Remove PT_FEAT_DYNAMIC_TOP from PT_FORCE_ENABLED_FEATURES
Date: Wed, 11 Mar 2026 13:44:03 -0300 [thread overview]
Message-ID: <20260311164403.GC1448102@nvidia.com> (raw)
In-Reply-To: <ed1715de-951e-4794-932e-577aee2c76f6@amd.com>
On Wed, Mar 11, 2026 at 09:54:55PM +0530, Vasant Hegde wrote:
>
> + Jason
>
> On 3/9/2026 7:35 PM, Ankit Soni wrote:
> > Dynamic top is used to grow the page table levels. However, if the VA
> > size is small and the initial page table level already covers the entire
> > address space, table growth is not required. In that case, the generic
> > page table framework clears PT_FEAT_DYNAMIC_TOP, which in turn causes
> > error -EOPNOTSUPP and leads to domain initialization failure.
> >
> > Remove PT_FEAT_DYNAMIC_TOP from PT_FORCE_ENABLED_FEATURES, since during
> > domain allocation AMD IOMMU driver explicitly sets PT_FEAT_DYNAMIC_TOP
> > via cfg.common.features, this keeps normal runtime behavior unchanged.
> >
>
> Fixes: 879ced2bab1 ("iommupt: Add the AMD IOMMU v1 page table format")
No.. There is no bug here.
I don't really understand why you'd want to do this, the driver still
sets PT_FEAT_DYNAMIC_TOP, so what is the issue?
It shouldn't be removed from PT_FORCE_ENABLED_FEATURES, something else
is wrong.
Jason
next prev parent reply other threads:[~2026-03-11 16:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-09 14:05 [PATCH v3 0/2] Respect VASIZE for address limits Ankit Soni
2026-03-09 14:05 ` [PATCH v3 1/2] iommu/amd: Remove PT_FEAT_DYNAMIC_TOP from PT_FORCE_ENABLED_FEATURES Ankit Soni
2026-03-11 16:24 ` Vasant Hegde
2026-03-11 16:44 ` Jason Gunthorpe [this message]
2026-03-12 4:10 ` Ankit Soni
2026-03-12 11:22 ` Jason Gunthorpe
2026-03-12 14:42 ` Ankit Soni
2026-03-09 14:05 ` [PATCH v3 2/2] iommu/amd: Adhere to IVINFO[VASIZE] for address limits Ankit Soni
2026-03-11 16:36 ` Vasant Hegde
2026-03-12 13:45 ` Jason Gunthorpe
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