This series comprises two related fixes:
- the FILL_RETURN_BUFFER macro in -next needs to access percpu data,
hence the GS segment base needs to be loaded before FILL_RETURN_BUFFER.
This means moving guest vmload/vmsave and host vmload to assembly
(patches 8 and 9).
- because AMD wants the OS to set STIBP to 1 before executing the
return thunk (un)training sequence, IA32_SPEC_CTRL must be restored
before UNTRAIN_RET, too. This must also be moved to assembly and,
for consistency, the guest SPEC_CTRL is also loaded in there
(patch 10).
Neither is particularly hard, however because of 32-bit systems one needs
to keep the number of arguments to __svm_vcpu_run to three or fewer.
Therefore, patches 2 to 7 move various accesses to the vcpu_svm struct
and to percpu data to vmenter.S, cleaning up various bits along the way
to keep the assembly code nice. I think the code is simpler than before
after these prerequisites, and even at the end of the series it is not
much harder to follow despite doing a lot more stuff. Care has been
taken to keep the "normal" and SEV-ES code as similar as possible,
even though the latter would not hit the three argument barrier; even
the prototype is the same.
The above summary leaves patch 1, which introduces a separate asm-offsets.c
file for KVM, so that kernel/asm-offsets.c does not have to do ugly includes
with ../ paths; and patch 11, which is just more dead code removal.
Thanks,
Paolo
v2->v3: store SME-adjusted save_area physical address in svm_cpu_data,
access it with PER_CPU_VAR instead of an argument [Sean, sort of]
split out-of-line spec-ctrl restore macro in two parts [Sean]
adjust comments to point out clobbered registers [Sean]
Paolo Bonzini (11):
KVM: x86: use a separate asm-offsets.c file
KVM: SVM: replace regs argument of __svm_vcpu_run with vcpu_svm
KVM: SVM: adjust register allocation for __svm_vcpu_run
KVM: SVM: retrieve VMCB from assembly
KVM: SVM: remove unused field from struct vcpu_svm
KVM: SVM: remove dead field from struct svm_cpu_data
KVM: SVM: do not allocate struct svm_cpu_data dynamically
KVM: SVM: move guest vmsave/vmload back to assembly
KVM: SVM: restore host save area from assembly
KVM: SVM: move MSR_IA32_SPEC_CTRL save/restore to assembly
x86, KVM: remove unnecessary argument to x86_virt_spec_ctrl and
callers
arch/x86/include/asm/spec-ctrl.h | 10 +-
arch/x86/kernel/asm-offsets.c | 6 -
arch/x86/kernel/cpu/bugs.c | 15 +-
arch/x86/kvm/.gitignore | 2 +
arch/x86/kvm/Makefile | 12 ++
arch/x86/kvm/kvm-asm-offsets.c | 29 ++++
arch/x86/kvm/svm/sev.c | 4 +-
arch/x86/kvm/svm/svm.c | 105 +++++--------
arch/x86/kvm/svm/svm.h | 11 +-
arch/x86/kvm/svm/svm_ops.h | 5 -
arch/x86/kvm/svm/vmenter.S | 260 +++++++++++++++++++++++++------
arch/x86/kvm/vmx/vmenter.S | 2 +-
12 files changed, 305 insertions(+), 156 deletions(-)
create mode 100644 arch/x86/kvm/.gitignore
create mode 100644 arch/x86/kvm/kvm-asm-offsets.c
--
2.31.1
