| Message ID | 20210526132026.270394-1-vkuznets@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: nVMX: Fixes for nested state migration when eVMCS is in use | expand |
Vitaly Kuznetsov <vkuznets@redhat.com> 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.
On 10/06/21 16:29, Vitaly Kuznetsov wrote: > Vitaly Kuznetsov <vkuznets@redhat.com> 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
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. Vitaly Kuznetsov (11): KVM: nVMX: Use '-1' in 'hv_evmcs_vmptr' to indicate that eVMCS is not in use KVM: nVMX: Don't set 'dirty_vmcs12' flag on enlightened VMPTRLD KVM: nVMX: Release eVMCS when enlightened VMENTRY was disabled KVM: nVMX: Make copy_vmcs12_to_enlightened()/copy_enlightened_to_vmcs12() return 'void' KVM: nVMX: Introduce 'EVMPTR_MAP_PENDING' post-migration state KVM: nVMX: Release enlightened VMCS on VMCLEAR KVM: nVMX: Ignore 'hv_clean_fields' data when eVMCS data is copied in vmx_get_nested_state() KVM: nVMX: Force enlightened VMCS sync from nested_vmx_failValid() KVM: nVMX: Reset eVMCS clean fields data from prepare_vmcs02() KVM: nVMX: Request to sync eVMCS from VMCS12 after migration KVM: selftests: evmcs_test: Test that KVM_STATE_NESTED_EVMCS is never lost arch/x86/kvm/vmx/evmcs.c | 3 + arch/x86/kvm/vmx/evmcs.h | 8 + arch/x86/kvm/vmx/nested.c | 144 +++++++++++------- arch/x86/kvm/vmx/nested.h | 11 +- arch/x86/kvm/vmx/vmx.c | 1 + .../testing/selftests/kvm/x86_64/evmcs_test.c | 64 ++++---- 6 files changed, 140 insertions(+), 91 deletions(-)