Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes: > Clean up KVM's PV TLB flushing when running with EPT on Hyper-V, i.e. as > a nested VMM. The terminology we use is a bit confusing and I'd like to use the opportunity to enlighten myself on how to call "PV TLB flushing" properly :-) Hyper-V supports two types of 'PV TLB flushing': HvFlushVirtualAddressSpace/HvFlushVirtualAddressList[,Ex] which is described in TLFS as ".. hypercall invalidates ... virtual TLB entries that belong to a specified address space." HvFlushGuestPhysicalAddressSpace/HvFlushGuestPhysicalAddressList which in TLFS is referred to as "... hypercall invalidates cached L2 GPA to GPA mappings within a second level address space... hypercall is like the execution of an INVEPT instruction with type “single-context” on all processors" and INVEPT is defined in SDM as "Invalidates mappings in the translation lookaside buffers (TLBs) and paging-structure caches that were derived from extended page tables (EPT)." (and that's what this series is about) and every time I see e.g. 'hv_remote_flush_tlb.*' it takes me some time to recall which flushing is this related to. Do you by any chance have any suggestions on how things can be improved? > No real goal in mind other than the sole patch in v1, which > is a minor change to avoid a future mixup when TDX also wants to define > .remote_flush_tlb. Everything else is opportunistic clean up. > Looks like a nice cleanup, thanks! > Ran Hyper-V KVM unit tests (if those are even relevant?) No, they aren't. KVM doesn't currently implement HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST so we can't test this feature outside of a real Hyper-V environment. We also don't yet test KVM-on-KVM with Enlightened VMCS ... > but haven't actually tested on top of Hyper-V. Just in case you are interested in doing so and there's no Hyper-V server around, you can either search for a Win10 desktop around or just spin an Azure VM where modern instance types (e.g. Dv3/v4, Ev3/v4 families, Intel only - so no Ea/Da/...) have VMX and PV Hyper-V features exposed. I'm going to give this a try today and I will also try to review individual patches, thanks again! > > v2: Rewrite everything. > > Sean Christopherson (10): > KVM: VMX: Track common EPTP for Hyper-V's paravirt TLB flush > KVM: VMX: Stash kvm_vmx in a local variable for Hyper-V paravirt TLB > flush > KVM: VMX: Fold Hyper-V EPTP checking into it's only caller > KVM: VMX: Do Hyper-V TLB flush iff vCPU's EPTP hasn't been flushed > KVM: VMX: Invalidate hv_tlb_eptp to denote an EPTP mismatch > KVM: VMX: Don't invalidate hv_tlb_eptp if the new EPTP matches > KVM: VMX: Explicitly check for hv_remote_flush_tlb when loading pgd > KVM: VMX: Define Hyper-V paravirt TLB flush fields iff Hyper-V is > enabled > KVM: VMX: Skip additional Hyper-V TLB EPTP flushes if one fails > KVM: VMX: Track PGD instead of EPTP for paravirt Hyper-V TLB flush > > arch/x86/kvm/vmx/vmx.c | 102 ++++++++++++++++++++--------------------- > arch/x86/kvm/vmx/vmx.h | 16 +++---- > 2 files changed, 57 insertions(+), 61 deletions(-) -- Vitaly
