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Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] >>> >>> On Mon, 20 Apr 2026 08:42:02 +0000 Vasant Hegde 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. >> >> Do you have dmesg? >> >>> >>> 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. >>>> Could you help in fixing this issue? >> >> Sure. We will try to reproduce it internally and get back to you. > > Hi, > > Just following up, were you able to reproduce this? So far no luck with SEV and SEV/SNP. > > I was able to trace down the hang to this do while loop [1]. In allocation path, we explicitly set 4K pages (iommu_alloc_4k_pages()). If SNP is enabled in host, then in shutdown path, amd_iommu_snp_disable() gets called and it tries to mark event log memory as shared. In this path, it calls rmpupdate. But I can't think of reason for it to hang in the rmpupdate loop. @Tom, Ashish, Any idea? > > Could this be a firmware bug? We are currently running 1.53 (below > shows up in the dmesg). > > [ 22.245942] ccp 0000:41:00.1: SEV-SNP API:1.53 build:5 > [ 22.308933] ccp 0000:41:00.1: SEV API:1.53 build:5 We are on [ 24.783307] ccp 0000:46:00.1: SEV-SNP API:1.55 build:29 [ 24.844646] ccp 0000:46:00.1: SEV API:1.55 build:29 Is it possible to upgrade BIOS and verify? Can you please share the dmesg of the booted system (before doing the kexec)? -Vasant