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    SubjectRe: [PATCH v3 00/14] Add Secure TSC support for SNP guests
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    On 7/22/2023 4:48 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:
    > 01-07: Preparation and movement of sev-guest driver code
    > 08-14: SecureTSC enablement patches.

    A gentle reminder.

    Thanks
    Nikunj

    >
    > Testing SecureTSC
    > -----------------
    >
    > SecureTSC hypervisor patches based on top of SEV-SNP UPM series:
    > https://github.com/nikunjad/linux/tree/snp-host-latest-securetsc
    >
    > QEMU changes:
    > https://github.com/nikunjad/qemu/tree/snp_securetsc
    >
    > QEMU commandline SEV-SNP-UPM with SecureTSC:
    >
    > qemu-system-x86_64 -cpu EPYC-Milan-v2,+secure-tsc \
    > -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=protected \
    > ...
    >
    > Changelog:
    > ----------
    > 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
    >
    > 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@alien8.de/
    >
    > v1: https://lore.kernel.org/r/20230130120327.977460-1-nikunj@amd.com/
    >
    > Nikunj A Dadhania (14):
    > virt: sev-guest: Use AES GCM crypto library
    > virt: sev-guest: Move mutex to SNP guest device structure
    > virt: sev-guest: Replace pr_debug with dev_dbg
    > 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
    > x86/sev: Move and reorganize sev guest request api
    > x86/mm: Add generic guest initialization hook
    > 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/tsc: Mark Secure TSC as reliable clocksource
    > x86/sev: Enable Secure TSC for SNP guests
    >
    > arch/x86/Kconfig | 1 +
    > arch/x86/boot/compressed/sev.c | 2 +-
    > arch/x86/coco/core.c | 3 +
    > arch/x86/include/asm/sev-guest.h | 175 +++++++
    > arch/x86/include/asm/sev.h | 19 +-
    > arch/x86/include/asm/svm.h | 6 +-
    > arch/x86/include/asm/x86_init.h | 2 +
    > arch/x86/kernel/kvmclock.c | 2 +-
    > arch/x86/kernel/sev-shared.c | 7 +
    > arch/x86/kernel/sev.c | 631 +++++++++++++++++++++--
    > arch/x86/kernel/tsc.c | 2 +-
    > arch/x86/kernel/x86_init.c | 2 +
    > arch/x86/mm/mem_encrypt.c | 13 +-
    > arch/x86/mm/mem_encrypt_amd.c | 6 +
    > drivers/virt/coco/sev-guest/Kconfig | 2 -
    > drivers/virt/coco/sev-guest/sev-guest.c | 638 +++---------------------
    > drivers/virt/coco/sev-guest/sev-guest.h | 63 ---
    > include/linux/cc_platform.h | 8 +
    > 18 files changed, 882 insertions(+), 700 deletions(-)
    > create mode 100644 arch/x86/include/asm/sev-guest.h
    > delete mode 100644 drivers/virt/coco/sev-guest/sev-guest.h
    >
    >
    > base-commit: 6995e2de6891c724bfeb2db33d7b87775f913ad1

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