On Wed, Jan 24, 2024 at 10:08 PM Nikunj A. Dadhania <nikunj@xxxxxxx> wrote: > > On 12/20/2023 8:43 PM, Nikunj A Dadhania wrote: > > Secure TSC allows guests to securely use RDTSC/RDTSCP instructions as the > > parameters being used cannot be changed by hypervisor once the guest is > > launched. More details in the AMD64 APM Vol 2, Section "Secure TSC". > > > > During the boot-up of the secondary cpus, SecureTSC enabled guests need to > > query TSC info from AMD Security Processor. This communication channel is > > encrypted between the AMD Security Processor and the guest, the hypervisor > > is just the conduit to deliver the guest messages to the AMD Security > > Processor. Each message is protected with an AEAD (AES-256 GCM). See "SEV > > Secure Nested Paging Firmware ABI Specification" document (currently at > > https://www.amd.com/system/files/TechDocs/56860.pdf) section "TSC Info" > > > > Use a minimal GCM library to encrypt/decrypt SNP Guest messages to > > communicate with the AMD Security Processor which is available at early > > boot. > > > > SEV-guest driver has the implementation for guest and AMD Security > > Processor communication. As the TSC_INFO needs to be initialized during > > early boot before smp cpus are started, move most of the sev-guest driver > > code to kernel/sev.c and provide well defined APIs to the sev-guest driver > > to use the interface to avoid code-duplication. > > > > Patches: > > 01-08: Preparation and movement of sev-guest driver code > > 09-16: SecureTSC enablement patches. > > > > Testing SecureTSC > > ----------------- > > > > SecureTSC hypervisor patches based on top of SEV-SNP Guest MEMFD series: > > https://github.com/nikunjad/linux/tree/snp-host-latest-securetsc_v5 > > > > QEMU changes: > > https://github.com/nikunjad/qemu/tree/snp_securetsc_v5 > > > > QEMU commandline SEV-SNP-UPM with SecureTSC: > > > > qemu-system-x86_64 -cpu EPYC-Milan-v2,+secure-tsc,+invtsc -smp 4 \ > > -object memory-backend-memfd-private,id=ram1,size=1G,share=true \ > > -object sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1,secure-tsc=on \ > > -machine q35,confidential-guest-support=sev0,memory-backend=ram1,kvm-type=snp \ > > ... > > > > Changelog: > > ---------- > > v7: > > * Drop mutex from the snp_dev and add snp_guest_cmd_{lock,unlock} API > > * Added comments for secrets page failure > > * Added define for maximum supported VMPCK > > * Updated comments why sev_status is used directly instead of > > cpu_feature_enabled() > > A gentle reminder. > >From the Google testing side of things, we may not get to this for another while. > Regards > Nikunj > -- -Dionna Glaze, PhD (she/her)
