Many AMD CPU Feature Additions Land In Linux 6.13
In addition to AMD P-State being the default now for 5th Gen EPYC CPUs rather than the generic ACPI CPUFreq driver to provide greater power efficiency, there is a lot more in tow. There is also the introduction of the AMD 3D V-Cache Optimizer driver and other changes. Merged yesterday providing several new AMD features was the x86/cpu pull request that is predominantly AMD processor changes. The x86/cpu highlights for the Linux 6.13 merge window include:
- Add a feature flag which denotes AMD CPUs supporting workload classification with the purpose of using such hints when making scheduling decisions
- Determine the boost enumerator for each AMD core based on its type: efficiency or performance, in the cppc driver
- Add the type of a CPU to the topology CPU descriptor with the goal of supporting and making decisions based on the type of the respective core
- Add a feature flag to denote AMD cores which have heterogeneous topology and enable SD_ASYM_PACKING for those
- Check microcode revisions before disabling PCID on Intel
- Cleanups and fixlets
A lot continues to be going on around better supporting AMD heterogeneous processors under Linux with a mix of performance "classic" and efficiency "dense" cores. There's the AMD heterogeneous topology patches in this pull, workload classification bits, and other bits.
Separately was also the x86/sev pull request of AMD Secure Encrypted Virtualization (SEV) updates for Linux 6.13:
- Do the proper memory conversion of guest memory in order to be able to kexec kernels in SNP guests along with other adjustments and cleanups to that effect
- Start converting and moving functionality from the sev-guest driver intocore code with the purpose of supporting the secure TSC SNP feature where the hypervisor cannot influence the TSC exposed to the guest anymore
- Add a "nosnp" cmdline option in order to be able to disable SNP support in the hypervisor and thus free-up resources which are not going to be used
Plus other AMD changes still coming for Linux 6.13 by way of the x86 platform drivers and AMDGPU/AMDKFD kernel graphics driver changes, among updates in other subsystems too for AMD's growing variety of products.
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