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Re: [Qemu-devel] [PATCH v3 22/22] RFC: target-arm: Use a 1:1 mapping bet
From: |
Edgar E. Iglesias |
Subject: |
Re: [Qemu-devel] [PATCH v3 22/22] RFC: target-arm: Use a 1:1 mapping between EL and MMU index |
Date: |
Tue, 20 May 2014 23:55:45 +1000 |
User-agent: |
Mutt/1.5.21+155 (d3096e8796e7) (2012-12-30) |
On Tue, May 20, 2014 at 02:47:49PM +0100, Peter Maydell wrote:
> On 20 May 2014 14:28, Edgar E. Iglesias <address@hidden> wrote:
> > On Tue, May 20, 2014 at 09:47:47AM +0000, Aggeler Fabian wrote:
> >> I guess this makes sense. Shouldn’t we implement two more MMUs to separate
> >> S-EL0/EL0 and S-EL1/EL1
> >> at least for ARMv8 with EL3 running in Aarch64 state?
> >
> > Maybe with future patches. My understanding is that on aarch64 the world
> > switch between S/NS requires EL3 firmware to reprogram the TTBR regs.
> > Currently in QEMU, the re-programming of TTBR will flush the TLBs. We would
> > need to do something about that before adding MMU tables for aarch64 Secure
> > EL0/1 does any good. I think it's better to keep it simple for now and leave
> > this as a possible future optimization.
> >
> > Another possible future optimization is to add some kind of dynamic
> > allocation
> > of a limited set of MMU tables for different ASIDs and VMIDs. For emulated
> > virtualization, it might help quite a bit.
>
> I think the right way to do that is to have QEMU's TLB
> structure include some sort of general equivalent to the
> ASID/VMID mechanism (presumably other target CPUs have some
> equivalent). Then we can honour 'flush by ASID' as well.
> (We make a forlorn gesture in this direction with the
> completely ignored 'flush_global' parameter to tlb_flush().)
Makes sense.
Cheers,
Edgar
>
> This is all definitely 'maybe future' stuff though.)
>
> thanks
> -- PMM
- [Qemu-devel] [PATCH v3 20/22] target-arm: A64: Register VBAR_EL3, (continued)
Re: [Qemu-devel] [PATCH v3 00/22] target-arm: Preparations for A64 EL2 and 3, Peter Crosthwaite, 2014/05/20
Re: [Qemu-devel] [PATCH v3 00/22] target-arm: Preparations for A64 EL2 and 3, Peter Maydell, 2014/05/21