On Mon, 7 Dec 2020 at 14:48, Steven Price <steven.price@xxxxxxx> wrote: > Sounds like you are making good progress - thanks for the update. Have > you thought about how the PROT_MTE mappings might work if QEMU itself > were to use MTE? My worry is that we end up with MTE in a guest > preventing QEMU from using MTE itself (because of the PROT_MTE > mappings). I'm hoping QEMU can wrap its use of guest memory in a > sequence which disables tag checking (something similar will be needed > for the "protected VM" use case anyway), but this isn't something I've > looked into. It's not entirely the same as the "protected VM" case. For that the patches currently on list basically special case "this is a debug access (eg from gdbstub/monitor)" which then either gets to go via "decrypt guest RAM for debug" or gets failed depending on whether the VM has a debug-is-ok flag enabled. For an MTE guest the common case will be guests doing standard DMA operations to or from guest memory. The ideal API for that from QEMU's point of view would be "accesses to guest RAM don't do tag checks, even if tag checks are enabled for accesses QEMU does to memory it has allocated itself as a normal userspace program". thanks -- PMM _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
