On 17 June 2014 23:10, James Hogan <james.hogan@xxxxxxxxxx> wrote: > The patchset depends on v4 of "target-mips: implement UserLocal > Register". I'm aiming for QEMU 2.1, hopefully it isn't too late to get > some final review. > > Thanks to everybody who has already taken part in review. > > This patchset implements KVM support for MIPS32 processors, using Trap & > Emulation. I was looking at what happens for MMIO accesses to nonexistent memory when we're running under KVM, and interestingly this patchset means MIPS is now the only CPU which both (a) supports KVM and (b) has an implementation of the do_unassigned_access() CPU hook. Does the current code support a guest attempt to access unassigned physical addresses? I had a look at the code and it seems like mips_cpu_unassigned_access() will end up calling cpu_restore_state() and cpu_loop_exit(), which I think will probably crash if you call them when using KVM rather than TCG... More generally, there doesn't really seem to be provision in the KVM KVM_EXIT_MMIO API for returning "this access failed". I guess in theory userspace could do all the "figure out how to adjust CPU state to do exception entry and then run VCPU", but that seems like quite a lot of work which the kernel already knows how to do; is there some way to provide a simpler API that lets userspace just inform the kernel that it needs to fault the access? thanks -- PMM -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
