[v2,0/4] Fix broken SNP support with KVM module built-in

Message

Kalra, Ashish Jan. 31, 2025, 1:08 a.m. UTC

From: Ashish Kalra <[e-mail]>

This patch-set fixes the current SNP host enabling code and effectively SNP
which is broken with respect to the KVM module being built-in.

Essentially SNP host enabling code should be invoked before KVM
initialization, which is currently not the case when KVM is built-in.

SNP host support is currently enabled in snp_rmptable_init() which is
invoked as a device_initcall(). Here device_initcall() is used as
snp_rmptable_init() expects AMD IOMMU SNP support to be enabled prior
to it and the AMD IOMMU driver enables SNP support after PCI bus enumeration.

This patch-set adds support to call snp_rmptable_init() early and
directly from iommu_snp_enable() (after checking and enabling IOMMU
SNP support) which enables SNP host support before KVM initialization
with kvm_amd module built-in.

Additionally the patch-set adds support to initialize PSP SEV driver
during KVM module probe time.

This patch-set has been tested with the following cases/scenarios:
1). kvm_amd module built-in.
2). kvm_amd module built-in with intremap=off kernel command line.
3). kvm_amd module built-in with iommu=off kernel command line.
4). kvm_amd built as a module.
5). kvm_amd built as module with iommu=off kernel command line.

v2:
- Drop calling iommu_snp_enable() early before enabling IOMMUs as
IOMMU subsystem gets initialized via subsys_initcall() and hence
snp_rmptable_init() cannot be invoked via subsys_initcall().
- Instead add support to call snp_rmptable_init() early and
directly via iommu_snp_enable().
- Fix commit logs.

Fixes: c3b86e61b756 ("x86/cpufeatures: Enable/unmask SEV-SNP CPU feature")

Ashish Kalra (1):
  x86/sev: Fix broken SNP support with KVM module built-in

Sean Christopherson (3):
  crypto: ccp: Add external API interface for PSP module initialization
  KVM: SVM: Ensure PSP module is initialized if KVM module is built-in
  iommu/amd: Enable Host SNP support after enabling IOMMU SNP support

 arch/x86/include/asm/sev.h  |  2 ++
 arch/x86/kvm/svm/sev.c      | 10 ++++++++++
 arch/x86/virt/svm/sev.c     | 23 +++++++----------------
 drivers/crypto/ccp/sp-dev.c | 14 ++++++++++++++
 drivers/iommu/amd/init.c    | 18 ++++++++++++++----
 include/linux/psp-sev.h     |  9 +++++++++
 6 files changed, 56 insertions(+), 20 deletions(-)