[PATCH v2 0/2] KVM: arm64: Fix handling of S1PTW

[Will Deacon]

On Tue, Sep 15, 2020 at 11:42:16AM +0100, Marc Zyngier wrote:
> I recently managed to trigger an interesting failure mode, where a
> guest would be stuck on an instruction abort due to a permission
> fault. Interestingly enough, this IABT had S1PTW set in the ESR,
> indicating that it was trying to *write* to the PT. We fix it by
> adding the execute permission (it's an IABT, after all...), and going
> nowhere fast.
> 
> Note that it can only happen on a system that can perform automatic
> updates of the page table flags.
> 
> This small series fixes the issue by revamping the S1PTW handling in
> the context of execution faults. The first patch fixes the bug, and is
> definitely a stable candidate. The second patch is merely a cleanup,
> which can wait.
> 
> Tested on an A55-based board.
> 
> * From v1:
>   - Rename kvm_vcpu_dabt_iss1tw() to kvm_vcpu_abt_iss1tw()
>   - Don't overload kvm_vcpu_trap_is_iabt()
>   - Introduce kvm_vcpu_trap_is_exec_fault()

For both patches:

Reviewed-by: Will Deacon <will at kernel.org>

Cheers,

Will