Hi Andrew,
On 30/07/2020 16:18, Andrew Scull wrote:
> The ESB at the start of the vectors causes any SErrors to be consumed to
> DISR_EL1. If the exception came from the host and the ESB caught an
> SError, it would not be noticed until a guest exits and DISR_EL1 is
> checked. Further, the SError would be attributed to the guest and not
> the host.
Yup, this happens because the world has moved underneath this code:
Previously any v8.2 RAS capable system would have been crazy to turn off VHE, so v8.0 and
v8.1 systems had a nop here instead, and v8.2 systems had VHE, so there were no 'from the
host' EL2 vectors.
> To avoid these problems, use a different exception vector for the host
> that does not use an ESB but instead leaves any host SError pending. A
> guest will not be entered if an SError is pending so it will always be
> the host that will receive and handle it.
>
> Hyp initialization is now passed the vector that is used for the host
> and the vector for guests is stored in a percpu variable as
> kvm_get_hyp_vector() is not suitable for calling from nVHE hyp.
> Fixes: 0e5b9c085dce ("KVM: arm64: Consume pending SError as early as possible")
Surely this can only happen if you had turned VHE off?
Thanks,
James
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