On 10/06/21 16:29, Vitaly Kuznetsov wrote:
Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes:Changes since v2: - 'KVM: nVMX: Use '-1' in 'hv_evmcs_vmptr' to indicate that eVMCS is not in use'/ 'KVM: nVMX: Introduce 'EVMPTR_MAP_PENDING' post-migration state' patches instead of 'KVM: nVMX: Introduce nested_evmcs_is_used()' [Paolo] - 'KVM: nVMX: Don't set 'dirty_vmcs12' flag on enlightened VMPTRLD' patch added [Max] - 'KVM: nVMX: Release eVMCS when enlightened VMENTRY was disabled' patch added. - 'KVM: nVMX: Make copy_vmcs12_to_enlightened()/copy_enlightened_to_vmcs12() return 'void'' patch added [Paolo] - R-b tags added [Max] Original description: Commit f5c7e8425f18 ("KVM: nVMX: Always make an attempt to map eVMCS after migration") fixed the most obvious reason why Hyper-V on KVM (e.g. Win10 + WSL2) was crashing immediately after migration. It was also reported that we have more issues to fix as, while the failure rate was lowered signifincatly, it was still possible to observe crashes after several dozens of migration. Turns out, the issue arises when we manage to issue KVM_GET_NESTED_STATE right after L2->L2 VMEXIT but before L1 gets a chance to run. This state is tracked with 'need_vmcs12_to_shadow_sync' flag but the flag itself is not part of saved nested state. A few other less significant issues are fixed along the way. While there's no proof this series fixes all eVMCS related problems, Win10+WSL2 was able to survive 3333 (thanks, Max!) migrations without crashing in testing. Patches are based on the current kvm/next tree.Paolo, Max, Just to double-check: are we good here? I know there are more improvements/ideas to explore but I'd like to treat this patchset as a set of fixes, it would be unfortunate if we miss 5.14.
Yes, I was busy the last couple of weeks but I am back now. Paolo
