[kvmarm] [PATCH 10/15] KVM: ARM: World-switch implementation

Peter Maydell peter.maydell at linaro.org
Sun Sep 30 05:48:48 EDT 2012

On 30 September 2012 01:33, Christoffer Dall
<c.dall at virtualopensystems.com> wrote:
> On Tue, Sep 25, 2012 at 1:42 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
>> Well, we're still in HYP mode when performing the pop, so the VMID is
>> pretty much irrelevant. Same for the initial push, actually. As long as
>> we're sure VTTBR has been updated when we do the exception return, I think
>> we're safe.
> yeah we're safe, but I can't find anywhere that says the ISB is
> implied from exception handling/hvc, even though I seem to recall
> having read this, so I put this here not to worry other readers.

"TLB maintenance operations and the memory order model" in section
B3.10.1 of the ARM ARM says that exception entry forces completion of
TLB maintenance ops. Section B5.6.3 ("Synchronization of changes to
system control registers") says that taking an exception synchronizes
context, so the VTTBR update is guaranteed to have happened.

-- PMM

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