Sean Christopherson <seanjc@xxxxxxxxxx> writes: > On Fri, Dec 02, 2022, Vitaly Kuznetsov wrote: >> In kvm_hv_flush_tlb(), 'data_offset' and 'consumed_xmm_halves' variables >> are used in a mutually exclusive way: in 'hc->fast' we count in 'XMM >> halves' and increase 'data_offset' otherwise. Coverity discovered, that in >> one case both variables are incremented unconditionally. This doesn't seem >> to cause any issues as the only user of 'data_offset'/'consumed_xmm_halves' >> data is kvm_hv_get_tlb_flush_entries() -> kvm_hv_get_hc_data() which also >> takes into account 'hc->fast' but is still worth fixing. > > If those calls aren't inlined, then 32-bit Hyper-V will be "consuming" uninitialized > data when pushing parameters onto the stack. It won't cause real problems, but > checkers might complain. > > What about shoving this metadata into "struct kvm_hv_hcall" as a union? That'd > help convey that the two are mutually exclusive, would provide a place to document > said exclusion, and would yield a nice cleanup too by eliminating multiple params > from various functions. "struct kvm_hv_hcall" used to hold raw data from the guest and 'consumed_xmm_halves'/ 'data_offset' are rather our implementation details, how we consume these data. I don't see why we can't re-purpose it a little bit to hold both, let me try that in v2. -- Vitaly
