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 5 and 6).
- 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 7).
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.
One is taken for whether IA32_SPEC_CTRL is intercepted, and one for the
host save area, so all accesses to the vcpu_svm struct have to be done
from assembly too. This is done in patches 2 to 4, and it turns out
not to be that bad; in fact 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.
The above summary leaves out the more mundane patches 1 and 8. The
former introduces a separate asm-offsets.c file for KVM, so that
kernel/asm-offsets.c does not have to do ugly includes with ../ paths.
The latter is dead code removal.
Thanks,
Paolo
v1->v2: use a separate asm-offsets.c file instead of hacking around
the arch/x86/kvm/svm/svm.h file; this could have been done
also with just a "#ifndef COMPILE_OFFSETS", but Sean's
suggestion is cleaner and there is a precedent in
drivers/memory/ for private asm-offsets files
keep preparatory cleanups together at the beginning of the
series
move SPEC_CTRL save/restore out of line [Jim]
Paolo Bonzini (8):
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: move guest vmsave/vmload 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/Makefile | 12 ++
arch/x86/kvm/kvm-asm-offsets.c | 28 ++++
arch/x86/kvm/svm/svm.c | 53 +++----
arch/x86/kvm/svm/svm.h | 4 +-
arch/x86/kvm/svm/svm_ops.h | 5 -
arch/x86/kvm/svm/vmenter.S | 241 ++++++++++++++++++++++++-------
arch/x86/kvm/vmx/vmenter.S | 2 +-
10 files changed, 259 insertions(+), 117 deletions(-)
create mode 100644 arch/x86/kvm/kvm-asm-offsets.c
--
2.31.1
