[PATCH v1 00/26] Add AMD Secure Nested Paging (SEV-SNP) Initialization Support

Michael Roth
2023-12-30T16:28:45Z

This patchset is also available at:

https://github.com/amdese/linux/commits/snp-host-init-v1

and is based on top of linux-next tag next-20231222

These patches were originally included in v10 of the SNP KVM/hypervisor
patches[1], but have been split off from the general KVM support for easier
review and eventual merging into the x86 tree. They are based on linux-next
to help stay in sync with both tip and kvm-next.

There is 1 KVM-specific patch here since it is needed to avoid regressions
when running legacy SEV guests while the RMP table is enabled.

== OVERVIEW ==

AMD EPYC systems utilizing Zen 3 and newer microarchitectures add support
for a new feature called SEV-SNP, which adds Secure Nested Paging support
on top of the SEV/SEV-ES support already present on existing EPYC systems.

One of the main features of SNP is the addition of an RMP (Reverse Map)
table to enforce additional security protections for private guest memory.
This series primarily focuses on the various host initialization
requirements for enabling SNP on the system, while the actual KVM support
for running SNP guests is added as a separate series based on top of these
patches.

The basic requirements to initialize SNP support on a host when the feature
has been enabled in the BIOS are:

- Discovering and initializing the RMP table
- Initializing various MSRs to enable the capability across CPUs
- Various tasks to maintain legacy functionality on the system, such as:
- Setting up hooks for handling RMP-related changes for IOMMU pages
- Initializing SNP in the firmware via the CCP driver, and implement
additional requirements needed for continued operation of legacy
SEV/SEV-ES guests

Additionally some basic SEV ioctl interfaces are added to configure various
aspects of SNP-enabled firmwares via the CCP driver.

More details are available in the SEV-SNP Firmware ABI[2].

== KNOWN ISSUES ==

- When SNP is enabled, it has been observed that TMR allocation may fail when
reloading CCP driver after kexec. This is being investigated.

Feedback/review is very much appreciated!

-Mike

[1] https://lore.kernel.org/kvm/20231016132819.1002933-1-michael.roth@amd.com/
[2] https://www.amd.com/en/developer/sev.html

Changes since being split off from v10 hypervisor patches:

* Move all host initialization patches to beginning of overall series and
post as a separate patchset. Include only KVM patches that are necessary
for maintaining legacy SVM/SEV functionality with SNP enabled.
(Paolo, Boris)
* Don't enable X86_FEATURE_SEV_SNP until all patches are in place to maintain
legacy SVM/SEV/SEV-ES functionality when RMP table and SNP firmware support
are enabled. (Paolo)
* Re-write how firmware-owned buffers are handled when dealing with legacy
SEV commands. Allocate on-demand rather than relying on pre-allocated pool,
use a descriptor format for handling nested/pointer params instead of
relying on macros. (Boris)
* Don't introduce sev-host.h, re-use sev.h (Boris)
* Various renames, cleanups, refactorings throughout the tree (Boris)
* Rework leaked pages handling (Vlastimil)
* Fix kernel-doc errors introduced by series (Boris)
* Fix warnings when onlining/offlining CPUs (Jeremi, Ashish)
* Ensure X86_FEATURE_SEV_SNP is cleared early enough that AutoIBRS will still
be enabled if RMP table support is not available/configured. (Tom)
* Only read the RMP base/end MSR values once via BSP (Boris)
* Handle IOMMU SNP setup automatically based on state machine rather than via
external caller (Boris)

----------------------------------------------------------------
Ashish Kalra (5):
iommu/amd: Don't rely on external callers to enable IOMMU SNP support
x86/mtrr: Don't print errors if MtrrFixDramModEn is set when SNP enabled
x86/sev: Introduce snp leaked pages list
iommu/amd: Clean up RMP entries for IOMMU pages during SNP shutdown
crypto: ccp: Add panic notifier for SEV/SNP firmware shutdown on kdump

Brijesh Singh (16):
x86/cpufeatures: Add SEV-SNP CPU feature
x86/sev: Add the host SEV-SNP initialization support
x86/sev: Add RMP entry lookup helpers
x86/fault: Add helper for dumping RMP entries
x86/traps: Define RMP violation #PF error code
x86/sev: Add helper functions for RMPUPDATE and PSMASH instruction
x86/sev: Invalidate pages from the direct map when adding them to the RMP table
crypto: ccp: Define the SEV-SNP commands
crypto: ccp: Add support to initialize the AMD-SP for SEV-SNP
crypto: ccp: Provide API to issue SEV and SNP commands
crypto: ccp: Handle the legacy TMR allocation when SNP is enabled
crypto: ccp: Handle legacy SEV commands when SNP is enabled
crypto: ccp: Add debug support for decrypting pages
KVM: SEV: Make AVIC backing, VMSA and VMCB memory allocation SNP safe
crypto: ccp: Add the SNP_PLATFORM_STATUS command
crypto: ccp: Add the SNP_SET_CONFIG command

Kim Phillips (1):
x86/speculation: Do not enable Automatic IBRS if SEV SNP is enabled

Michael Roth (2):
x86/fault: Dump RMP table information when RMP page faults occur
x86/cpufeatures: Enable/unmask SEV-SNP CPU feature

Tom Lendacky (2):
crypto: ccp: Handle non-volatile INIT_EX data when SNP is enabled
crypto: ccp: Add the SNP_COMMIT command

Documentation/virt/coco/sev-guest.rst | 51 ++
arch/x86/Kbuild | 2 +
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/disabled-features.h | 8 +-
arch/x86/include/asm/iommu.h | 1 +
arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/include/asm/msr-index.h | 11 +-
arch/x86/include/asm/sev.h | 36 +
arch/x86/include/asm/trap_pf.h | 20 +-
arch/x86/kernel/cpu/amd.c | 20 +-
arch/x86/kernel/cpu/common.c | 7 +-
arch/x86/kernel/cpu/mtrr/generic.c | 3 +
arch/x86/kernel/crash.c | 7 +
arch/x86/kvm/lapic.c | 5 +-
arch/x86/kvm/svm/nested.c | 2 +-
arch/x86/kvm/svm/sev.c | 37 +-
arch/x86/kvm/svm/svm.c | 17 +-
arch/x86/kvm/svm/svm.h | 1 +
arch/x86/mm/fault.c | 5 +
arch/x86/virt/svm/Makefile | 3 +
arch/x86/virt/svm/sev.c | 513 +++++++++++++
drivers/crypto/ccp/sev-dev.c | 1216 +++++++++++++++++++++++++++---
drivers/crypto/ccp/sev-dev.h | 5 +
drivers/iommu/amd/amd_iommu.h | 1 -
drivers/iommu/amd/init.c | 120 ++-
include/linux/amd-iommu.h | 6 +-
include/linux/psp-sev.h | 337 ++++++++-
include/uapi/linux/psp-sev.h | 59 ++
tools/arch/x86/include/asm/cpufeatures.h | 1 +
30 files changed, 2359 insertions(+), 138 deletions(-)
create mode 100644 arch/x86/virt/svm/Makefile
create mode 100644 arch/x86/virt/svm/sev.c