Re: [kvm-ppc-devel] KVM kernel/userspace TLB interface

[Avi Kivity <avi@qumranet.com>]

Hollis Blanchard wrote:
>       * Have a per-core interface, e.g. KVM_440_SET_TLB_ENTRY and
>         KVM_e500_SET_TLB_ENTRY. These would communicate via completely
>         different structures. For example, the 440 structure would look
>         something like { index, TID, word 0, word 1, word 2 }. We'd
>         probably want to sanity check each ioctl to make sure it matches
>         the vcpu type. Not only that, but we would need core-specific
>         code in userspace to actually make the call.
>       * Try to abstract it so that we have a higher-level "map this"
>         interface. This could look something like { virtual addr, real
>         addr, size, flags }. It's up to core-specific code to select in
>         which TLB to create the mapping, which entry to clobber,
>         interpret the meaning of "flags", etc. I guess the big downside
>         here is that if we want to dump guest state for debugging
>         purposes we'd still need the core-specific interface.
>
> We could also try supporting both #2 and #3, so that "generic" code like
> qemu could use the abstracted (and shared) "map this" call, while tools
> with more specific needs could still get at the underlying details. I
> guess #1 and #3 is like the normal userspace/kernel interface, where you
> don't ordinarily need to specify register details, but the ptrace
> interface is available when needed.
>   

An unabstracted interface is needed for save/restore/migrate, which may 
or may not be important for your target.  I do recommend having getters 
and setters for all architectural state.

-- 
error compiling committee.c: too many arguments to function


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