Re: [Xen-devel] [PATCH v2 1/3] x86 / vmx: make apic_access_mfn type-safe

[Jan Beulich <jbeulich@xxxxxxxx>]

On 23.01.2020 13:21, Paul Durrant wrote:
> Use mfn_t rather than unsigned long and change previous tests against 0 to
> tests against INVALID_MFN (also introducing initialization to that value).
> 
> Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
> Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

No, this isn't what the R-b was given for.

> v2:
>  - Set apic_access_mfn to INVALID_MFN in vmx_free_vlapic_mapping() to make
>    the function idempotent

Andrew had suggested to use 0 instead of INVALID_MFN. I don't see
how you achieved idempotency with this adjustment. Aiui
vmx_free_vlapic_mapping() is supposed to also run correctly if
vmx_alloc_vlapic_mapping() was never called.

Jan

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