Re: [PATCH 0/2] iommu/amd: Use MAX buffer size when SNP is enabled on Family 0x19

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Aug 13, 2026 at 06:18:30AM -0700, Usama Arif wrote:
> On Mon, 20 Apr 2026 08:42:02 +0000 Vasant Hegde <vasant.hegde@amd.com> wrote:
> 
> > This series addresses CVE-2023-20585 [1] by increasing the AMD IOMMU
> > Event log and PPR log buffer sizes to the maximum supported value (512K)
> > on affected CPU families when SNP is enabled.
> > 
> > Use MAX buffer size when SNP is enabled on Milan/Genoa. Impacted buffers:
> >   - Milan : Event log (PPR/GALog is not supported when SNP is enabled)
> >   - Genoa : Event and PPR log (GALog is not supported when SNP is enabled)
> >
> 
> Hi,
> 
> This series seems to break kexec in our production on Milan hosts with SEV enabled.
> This is on the 6.18.43 stable kernel backport.
> 
> If on top of 6.18.43 release, we revert the 2 commits, i.e.
> Revert "iommu/amd: Use maximum PPR log buffer size when SNP is enabled on Family 0x19"
> Revert "iommu/amd: Use maximum Event log buffer size when SNP is enabled on Family 0x19"
> 
> kexec starts working again.

This sounds like the same issue Nicolin is facing on SMMUv3, these
larger allocations OOM the kexec kernel

Jason