Currently there is a TOC/TOU race between the check of vmcb12's
efer, cr0 and cr4 registers and the later save of their values in
svm_set_*, because the guest could modify the values in the meanwhile.
To solve this issue, this serie introuces and uses svm->nested.save
structure in enter_svm_guest_mode to save the current value of efer,
cr0 and cr4 and later use these to set the vcpu->arch.* state.
Patch 1 just refactor the code to simplify the next two patches,
patch 2 introduces svm->nested.save to cache the efer, cr0 and cr4 fields
and in patch 3 we use it to avoid TOC/TOU races.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@xxxxxxxxxx>
---
v1 -> RFC:
- use svm->nested.save instead of local variables.
- not dependent anymore from "KVM: nSVM: remove useless kvm_clear_*_queue"
- simplified patches, we just use the struct and not move the check
nearer to the TOU.
Emanuele Giuseppe Esposito (3):
KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in
nested_vmcb_valid_sregs
nSVM: introduce smv->nested.save to cache save area fields
nSVM: use svm->nested.save to load vmcb12 registers and avoid TOC/TOU
races
arch/x86/kvm/svm/nested.c | 82 ++++++++++++++++++++-------------------
arch/x86/kvm/svm/svm.c | 1 +
arch/x86/kvm/svm/svm.h | 3 ++
3 files changed, 47 insertions(+), 39 deletions(-)
--
2.27.0
