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.
