[PATCH v11 00/20] Add Secure TSC support for SNP guests

[Nikunj A Dadhania]

This patchset is also available at:

  https://github.com/AMDESE/linux-kvm/tree/sectsc-guest-latest

and is based on v6.11-rc1

Overview
--------

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".

In order to enable secure TSC, SEV-SNP guests need to send TSC_INFO guest
message before the APs are booted. Details from the TSC_INFO response will
then be used to program the VMSA before the APs are brought up. See "SEV
Secure Nested Paging Firmware ABI Specification" document (currently at
https://www.amd.com/system/files/TechDocs/56860.pdf) section "TSC Info"

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 APs are started, move the guest messaging code from
sev-guest driver to sev/core.c and provide well defined APIs to the
sev-guest driver.

Patches:
01-04: sev-guest driver cleanup and enhancements
   05: Use AES GCM library
06-07: SNP init error handling and cache secrets page address
08-10: Preparatory patches for code movement
11-12: Patches moving SNP guest messaging code from SEV guest driver to
       SEV common code
13-20: SecureTSC enablement patches.

Testing SecureTSC
-----------------

SecureTSC hypervisor patches based on top of SEV-SNP Guest MEMFD series:
https://github.com/AMDESE/linux-kvm/tree/sectsc-host-latest

QEMU changes:
https://github.com/nikunjad/qemu/tree/snp-securetsc-latest

QEMU commandline SEV-SNP with SecureTSC:

  qemu-system-x86_64 -cpu EPYC-Milan-v2 -smp 4 \
    -object memory-backend-memfd,id=ram1,size=1G,share=true,prealloc=false,reserve=false \
    -object sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1,secure-tsc=on \
    -machine q35,confidential-guest-support=sev0,memory-backend=ram1 \
    ...

Changelog:
----------
v11:
* Rebased on top of v6.11-rc1
* Added Acked-by/Reviewed-by
* Moved SEV Guest driver cleanups in the beginning of the series
* Commit message updates
* Enforced PAGE_SIZE constraints for snp_guest_msg
* After offline discussion with Boris, redesigned and exported
  SEV guest messaging APIs to sev-guest driver
* Dropped VMPCK rework patches
* Make sure movement of SEV core routines does not break the SEV Guest
  driver midway of the series.

v10: https://lore.kernel.org/lkml/20240621123903.2411843-1-nikunj@xxxxxxx/
* Rebased on top of tip/x86/sev
* Added Reviewed-by from Tom
* Commit message updates
* Change the condition for better readability in get_vmpck()
* Make vmpck_id as u32 again and use VMPCK_MAX_NUM as the default value



Nikunj A Dadhania (20):
  virt: sev-guest: Replace dev_dbg with pr_debug
  virt: sev-guest: Rename local guest message variables
  virt: sev-guest: Fix user-visible strings
  virt: sev-guest: Ensure the SNP guest messages do not exceed a page
  virt: sev-guest: Use AES GCM crypto library
  x86/sev: Handle failures from snp_init()
  x86/sev: Cache the secrets page address
  virt: sev-guest: Consolidate SNP guest messaging parameters to a
    struct
  virt: sev-guest: Reduce the scope of SNP command mutex
  virt: sev-guest: Carve out SNP message context structure
  x86/sev: Carve out and export SNP guest messaging init routines
  x86/sev: Relocate SNP guest messaging routines to common code
  x86/cc: Add CC_ATTR_GUEST_SECURE_TSC
  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/sev: Allow Secure TSC feature for SNP guests
  x86/sev: Mark Secure TSC as reliable clocksource
  x86/kvmclock: Skip kvmclock when Secure TSC is available
  x86/cpu/amd: Do not print FW_BUG for Secure TSC

 arch/x86/include/asm/sev-common.h       |   1 +
 arch/x86/include/asm/sev.h              | 166 +++++-
 arch/x86/include/asm/svm.h              |   6 +-
 include/linux/cc_platform.h             |   8 +
 arch/x86/boot/compressed/sev.c          |   3 +-
 arch/x86/coco/core.c                    |   3 +
 arch/x86/coco/sev/core.c                | 590 ++++++++++++++++++--
 arch/x86/coco/sev/shared.c              |  10 +
 arch/x86/kernel/cpu/amd.c               |   3 +-
 arch/x86/kernel/kvmclock.c              |   2 +-
 arch/x86/mm/mem_encrypt.c               |   4 +
 arch/x86/mm/mem_encrypt_amd.c           |   4 +
 arch/x86/mm/mem_encrypt_identity.c      |   7 +
 drivers/virt/coco/sev-guest/sev-guest.c | 695 +++---------------------
 arch/x86/Kconfig                        |   1 +
 drivers/virt/coco/sev-guest/Kconfig     |   3 -
 16 files changed, 820 insertions(+), 686 deletions(-)


base-commit: 8400291e289ee6b2bf9779ff1c83a291501f017b
-- 
2.34.1