[PATCH v2 0/8] KVM: x86: allow compiling out SMM support

From: Paolo Bonzini
Date: Thu Sep 29 2022 - 13:20:43 EST


Some users of KVM implement the UEFI variable store through a paravirtual device
that does not require the "SMM lockbox" component of edk2; allow them to
compile out system management mode, which is not a full implementation
especially in how it interacts with nested virtualization.

In order to limit the number and especially the size of the #ifdefs,
the first 4 patches move most SMM code to a completely new file in
arch/x86/kvm. Patch 5 is the main change to introduce the Kconfig
symbol and key smm.c's compilation off it; patches 6-8 instead eliminate
other bits of SMM code that remain outside smm.c, the last one being
"optional" as it is a bit into diminishing returns land.

Paolo

Paolo Bonzini (8):
KVM: x86: start moving SMM-related functions to new files
KVM: x86: move SMM entry to a new file
KVM: x86: move SMM exit to a new file
KVM: x86: do not go through ctxt->ops when emulating rsm
KVM: allow compiling out SMM support
KVM: x86: compile out vendor-specific code if SMM is disabled
KVM: x86: remove SMRAM address space if SMM is not supported
KVM: x86: do not define KVM_REQ_SMI if SMM disabled

arch/x86/include/asm/kvm-x86-ops.h | 2 +
arch/x86/include/asm/kvm_host.h | 24 +-
arch/x86/kvm/Kconfig | 11 +
arch/x86/kvm/Makefile | 1 +
arch/x86/kvm/emulate.c | 355 +----------
arch/x86/kvm/kvm_cache_regs.h | 5 -
arch/x86/kvm/kvm_emulate.h | 47 +-
arch/x86/kvm/lapic.c | 14 +-
arch/x86/kvm/lapic.h | 7 +-
arch/x86/kvm/mmu/mmu.c | 1 +
arch/x86/kvm/smm.c | 573 ++++++++++++++++++
arch/x86/kvm/smm.h | 38 ++
arch/x86/kvm/svm/nested.c | 3 +
arch/x86/kvm/svm/svm.c | 11 +-
arch/x86/kvm/vmx/nested.c | 1 +
arch/x86/kvm/vmx/vmx.c | 7 +
arch/x86/kvm/x86.c | 353 +----------
tools/testing/selftests/kvm/x86_64/smm_test.c | 2 +
18 files changed, 737 insertions(+), 718 deletions(-)
create mode 100644 arch/x86/kvm/smm.c
create mode 100644 arch/x86/kvm/smm.h

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2.31.1