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() v6: * Add synthetic SecureTSC x86 feature bit * Drop {__enc,dec}_payload() as they are pretty small and has one caller. * Instead of a pointer use data_npages as variable * Beautify struct snp_guest_req * Make vmpck_id as unsigned int in snp_assign_vmpck() * Move most of the functions to end of sev.c file * Update commit/comments/error messages * Mark free_shared_pages and alloc_shared_pages as inline * Free snp_dev->certs_data when guest driver is removed * Add lockdep assert in snp_inc_msg_seqno() * Drop redundant enc_init NULL check * Move SNP_TSC_INFO_REQ_SZ define out of structure * Rename guest_tsc_{scale,offset} to snp_tsc_{scale,offset} * Add new linux termination error code GHCB_TERM_SECURE_TSC * Initialize and use cmd_mutex in snp_get_tsc_info() * Set TSC as reliable in sme_early_init() * Do not print firmware bug for Secure TSC enabled guests https://lore.kernel.org/lkml/20231128125959.1810039-1-nikunj@xxxxxxx/ v5: * Rebased on v6.6 kernel * Dropped link tag in first patch * Dropped get_ctx_authsize() as it was redundant https://lore.kernel.org/lkml/20231030063652.68675-1-nikunj@xxxxxxx/ v4: * Drop handle_guest_request() and handle_guest_request_ext() * Drop NULL check for key * Corrected commit subject * Added Reviewed-by from Tom https://lore.kernel.org/lkml/20230814055222.1056404-1-nikunj@xxxxxxx/ v3: * Updated commit messages * Made snp_setup_psp_messaging() generic that is accessed by both the kernel and the driver * Moved most of the context information to sev.c, sev-guest driver does not need to know the secrets page layout anymore * Add CC_ATTR_GUEST_SECURE_TSC early in the series therefore it can be used in later patches. * Removed data_gpa and data_npages from struct snp_req_data, as certs_data and its size is passed to handle_guest_request_ext() * Make vmpck_id as unsigned int * Dropped unnecessary usage of memzero_explicit() * Cache secrets_pa instead of remapping the cc_blob always * Rebase on top of v6.4 kernel https://lore.kernel.org/lkml/20230722111909.15166-1-nikunj@xxxxxxx/ v2: * Rebased on top of v6.3-rc3 that has Boris's sev-guest cleanup series https://lore.kernel.org/r/20230307192449.24732-1-bp@xxxxxxxxx/ v1: https://lore.kernel.org/r/20230130120327.977460-1-nikunj@xxxxxxx/ Nikunj A Dadhania (16): virt: sev-guest: Use AES GCM crypto library virt: sev-guest: Replace dev_dbg with pr_debug virt: sev-guest: Add SNP guest request structure virt: sev-guest: Add vmpck_id to snp_guest_dev struct x86/sev: Cache the secrets page address virt: sev-guest: Move SNP Guest command mutex x86/sev: Move and reorganize sev guest request api x86/mm: Add generic guest initialization hook x86/cpufeatures: Add synthetic Secure TSC bit x86/sev: Add Secure TSC support for SNP guests x86/sev: Change TSC MSR behavior for Secure TSC enabled guests x86/sev: Prevent RDTSC/RDTSCP interception for Secure TSC enabled guests x86/kvmclock: Skip kvmclock when Secure TSC is available x86/sev: Mark Secure TSC as reliable x86/cpu/amd: Do not print FW_BUG for Secure TSC x86/sev: Enable Secure TSC for SNP guests arch/x86/Kconfig | 1 + arch/x86/boot/compressed/sev.c | 3 +- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/sev-common.h | 1 + arch/x86/include/asm/sev-guest.h | 190 +++++++ arch/x86/include/asm/sev.h | 21 +- arch/x86/include/asm/svm.h | 6 +- arch/x86/include/asm/x86_init.h | 2 + arch/x86/kernel/cpu/amd.c | 3 +- arch/x86/kernel/kvmclock.c | 2 +- arch/x86/kernel/sev-shared.c | 10 + arch/x86/kernel/sev.c | 649 +++++++++++++++++++++-- arch/x86/kernel/x86_init.c | 2 + arch/x86/mm/mem_encrypt.c | 12 +- arch/x86/mm/mem_encrypt_amd.c | 12 + drivers/virt/coco/sev-guest/Kconfig | 3 - drivers/virt/coco/sev-guest/sev-guest.c | 668 +++--------------------- drivers/virt/coco/sev-guest/sev-guest.h | 63 --- 18 files changed, 917 insertions(+), 732 deletions(-) create mode 100644 arch/x86/include/asm/sev-guest.h delete mode 100644 drivers/virt/coco/sev-guest/sev-guest.h base-commit: ceb6a6f023fd3e8b07761ed900352ef574010bcb -- 2.34.1
