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 and 4 we use it to avoid TOC/TOU races.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@xxxxxxxxxx>
---
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.
v2:
* svm->nested.save is a separate struct vmcb_save_area_cached,
and not vmcb_save_area.
* update also vmcb02->cr3 with svm->nested.save.cr3
Emanuele Giuseppe Esposito (4):
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 vmcb_save_area_cached in nested_vmcb_valid_sregs()
nSVM: use svm->nested.save to load vmcb12 registers and avoid TOC/TOU
races
arch/x86/kvm/svm/nested.c | 95 +++++++++++++++++++++------------------
arch/x86/kvm/svm/svm.c | 1 +
arch/x86/kvm/svm/svm.h | 12 +++++
3 files changed, 64 insertions(+), 44 deletions(-)
--
2.27.0
