[PATCH v6 0/5] Add Guest API & Guest Kernel support for SEV live migration.

From: Ashish Kalra
Date: Tue Aug 24 2021 - 07:03:56 EST

From: Ashish Kalra <ashish.kalra@xxxxxxx>

The series adds guest api and guest kernel support for SEV live migration.

The patch series introduces a new hypercall. The guest OS can use this
hypercall to notify the page encryption status. If the page is encrypted
with guest specific-key then we use SEV command during the migration.
If page is not encrypted then fallback to default. This new hypercall
is invoked using paravirt_ops.

This section descibes how the SEV live migration feature is negotiated
between the host and guest, the host indicates this feature support via
KVM_FEATURE_CPUID. The guest firmware (OVMF) detects this feature and
sets a UEFI enviroment variable indicating OVMF support for live
migration, the guest kernel also detects the host support for this
feature via cpuid and in case of an EFI boot verifies if OVMF also
supports this feature by getting the UEFI enviroment variable and if it
set then enables live migration feature on host by writing to a custom
MSR, if not booted under EFI, then it simply enables the feature by
again writing to the custom MSR.

Changes since v5:
- Add detailed comments and explanation why SEV hypercalls need to
be made before apply_alternative() and how adding kvm_sev_hypercall3()
function is abstracted using the early_set_memory_XX() interfaces
invoking the paravirt_ops (pv_ops).
- Reverting to the earlier kvm_sev_hypercall3() interface after
feedback from Sean that inversion of KVM_HYPERCALL to VMMCALL
is causing issues and not going to work.

Changes since v4:
- Split the guest kernel support for SEV live migration and kexec support
for live migration into separate patches.

Changes since v3:
- Add Code style fixes as per review from Boris.

Changes since v2:
- Add guest api patch to this patchset.
- Replace KVM_HC_PAGE_ENC_STATUS hypercall with the more generic
- Add WARN_ONCE() messages if address lookup fails during kernel
page table walk while issuing KVM_HC_MAP_GPA_RANGE hypercall.

Changes since v1:
- Avoid having an SEV specific variant of kvm_hypercall3() and instead
invert the default to VMMCALL.

Ashish Kalra (4):
KVM: X86: Introduce KVM_HC_MAP_GPA_RANGE hypercall
KVM: x86: invert KVM_HYPERCALL to default to VMMCALL
EFI: Introduce the new AMD Memory Encryption GUID.
x86/kvm: Add guest support for detecting and enabling SEV Live
Migration feature.

Ashish Kalra (3):
EFI: Introduce the new AMD Memory Encryption GUID.
x86/kvm: Add guest support for detecting and enabling SEV Live
Migration feature.
x86/kvm: Add kexec support for SEV Live Migration.

Brijesh Singh (2):
x86/kvm: Add AMD SEV specific Hypercall3
mm: x86: Invoke hypercall when page encryption status is changed

arch/x86/include/asm/kvm_para.h | 12 +++
arch/x86/include/asm/mem_encrypt.h | 4 +
arch/x86/include/asm/paravirt.h | 6 ++
arch/x86/include/asm/paravirt_types.h | 1 +
arch/x86/include/asm/set_memory.h | 1 +
arch/x86/kernel/kvm.c | 107 ++++++++++++++++++++++++++
arch/x86/kernel/paravirt.c | 1 +
arch/x86/mm/mem_encrypt.c | 72 ++++++++++++++---
arch/x86/mm/pat/set_memory.c | 6 ++
include/linux/efi.h | 1 +
10 files changed, 202 insertions(+), 9 deletions(-)