[PATCH v3 0/7] Move initializing SEV/SNP functionality to KVM

Ashish Kalra
2025-01-03T19:59:18Z

From: Ashish Kalra <ashish.kalra@amd.com>

Remove initializing SEV/SNP functionality from PSP driver and instead add
support to KVM to explicitly initialize the PSP if KVM wants to use
SEV/SNP functionality.

This removes SEV/SNP initialization at PSP module probe time and does
on-demand SEV/SNP initialization when KVM really wants to use
SEV/SNP functionality. This will allow running legacy non-confidential
VMs without initializating SEV functionality.

This will assist in adding SNP CipherTextHiding support and SEV firmware
hotloading support in KVM without sharing SEV ASID management and SNP
guest context support between PSP driver and KVM and keeping all that
support only in KVM.

To support SEV firmware hotloading, SEV Shutdown will be done explicitly
prior to DOWNLOAD_FIRMWARE_EX and SEV INIT post it to work with the
requirement of SEV to be in UNINIT state for DOWNLOAD_FIRMWARE_EX.
NOTE: SEV firmware hotloading will only be supported if there are no
active SEV/SEV-ES guests.

v3:
- Move back to do both SNP and SEV platform initialization at KVM module
load time instead of SEV initialization on demand at SEV/SEV-ES VM launch
to prevent breaking QEMU which has a check for SEV to be initialized
prior to launching SEV/SEV-ES VMs.
- As both SNP and SEV platform initialization and shutdown is now done at
KVM module load and unload time remove patches for separate SEV and SNP
platform initialization and shutdown.

v2:
- Added support for separate SEV and SNP platform initalization, while
SNP platform initialization is done at KVM module load time, SEV
platform initialization is done on demand at SEV/SEV-ES VM launch.
- Added support for separate SEV and SNP platform shutdown, both
SEV and SNP shutdown done at KVM module unload time, only SEV
shutdown down when all SEV/SEV-ES VMs have been destroyed, this
allows SEV firmware hotloading support anytime during system lifetime.
- Updated commit messages for couple of patches in the series with
reference to the feedback received on v1 patches.

Ashish Kalra (7):
crypto: ccp: Move dev_info/err messages for SEV/SNP initialization
crypto: ccp: Fix implicit SEV/SNP init and shutdown in ioctls
crypto: ccp: Reset TMR size at SNP Shutdown
crypto: ccp: Register SNP panic notifier only if SNP is enabled
crypto: ccp: Add new SEV/SNP platform shutdown API
KVM: SVM: Add support to initialize SEV/SNP functionality in KVM
crypto: ccp: Move SEV/SNP Platform initialization to KVM

arch/x86/kvm/svm/sev.c | 15 ++-
drivers/crypto/ccp/sev-dev.c | 239 +++++++++++++++++++++++++----------
include/linux/psp-sev.h | 7 +-
3 files changed, 190 insertions(+), 71 deletions(-)

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2.34.1