Messages in this thread | | | From | Cathy Avery <> | Subject | [PATCH 0/2] KVM: SVM: Track physical cpu and asid_generation via the vmcb | Date | Tue, 12 Jan 2021 11:43:11 -0500 |
| |
In the cases where vmcbs change processors from one vmrun to another updated information in the vmcb from a prior run can potentially be lost. By tracking the physical cpu and asid_generation per vmcb instead of svm->vcpu the following scenario illustrated by Paolo can be avoided.
--------------------- --------------------- pCPU 1 pCPU 2 --------------------- --------------------- run VMCB02 run VMCB02 (*) run VMCB01 run VMCB01 (**) run VMCB02 (***) --------------------- ---------------------
After the point marked (*), while L2 runs, some fields change in VMCB02. When the processor vmexits back to L0, VMCB02 is marked clean.
At the point marked (**), svm->vcpu.cpu becomes 1 again.
Therefore, at the point marked (***) you will get svm->vcpu.cpu == cpu and the VMCB02 will not be marked dirty. The processor can then incorrectly use some data that is cached from before point (*).
Theses patches are intended for the kvm nested-svm branch.
The patches have been tested on nested fedora VMs, kvm self tests, and kvm-unit-tests. They have not been tested on SEV.
Cathy Avery (2): KVM: nSVM: Track the physical cpu of the vmcb vmrun through the vmcb KVM: nSVM: Track the ASID generation of the vmcb vmrun through the vmcb
arch/x86/kvm/svm/svm.c | 45 +++++++++++++++++++++++------------------- arch/x86/kvm/svm/svm.h | 3 ++- 2 files changed, 27 insertions(+), 21 deletions(-)
-- 2.20.1
| |