Messages in this thread | | | From | Emanuele Giuseppe Esposito <> | Subject | [PATCH v2 0/4] KVM: nSVM: avoid TOC/TOU race when checking vmcb12 | Date | Fri, 17 Sep 2021 08:03:25 -0400 |
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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@redhat.com>
--- 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
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