RE: [RFC PATCH 1/2] Drivers: hv: vmbus: add vmbus_establish_gpadl_caller_decrypted()

["Kameron Carr" <kameroncarr@linux.microsoft.com>]

On Thursday, July 23, 2026 10:53 AM, Michael Kelley wrote:
> From: Kameron Carr <kameroncarr@linux.microsoft.com> Sent: Tuesday, July
21, 2026 12:57 PM
> >
> > Refactor vmbus_establish_gpadl() to separate the encryption lifecycle
> > from the rest of the GPADL establishment logic.
> >
> > Add a new vmbus_establish_gpadl_caller_decrypted() for callers that want
> > to decrypt their own buffers.
> >
> > No functional change for existing callers.
> 
> I have a suggestion for a different way to accomplish this. I haven't
coded
> it, but I think it will result in less code churn and be simpler overall.
> 
> 1) In enum hv_gpadl_type, add value HV_GPADL_BUFFER_DECRYPTED
> 
> 2) Update hv_gpadl_size() and hv_gpadl_hvpfn() to treat the new enum
> value just like HV_GPADL_BUFFER
> 
> 3) In __vmbus_establish_gpadl(), change this code
> 
>         gpadl->decrypted = !((channel->co_external_memory && type ==
HV_GPADL_BUFFER) ||
>                 (channel->co_ring_buffer && type == HV_GPADL_RING));
> 
> to
> 
>         gpadl->decrypted = !((channel->co_external_memory && type ==
HV_GPADL_BUFFER) ||
>                 (channel->co_ring_buffer && type == HV_GPADL_RING) ||
> 	  (type == HV_GPADL_BUFFER_DECRYPTED));
> 
> 4) Add the function vmbus_establish_gpadl_caller_decrypted() like you
> have in this patch. It just calls __vmbus_establish_gpadl(), passing
> HV_GPADL_BUFFER_DECRYPTED.

Ack. Thank you for the feedback. I will use this approach in v2.

Regards,
Kameron

> I think that's all that is needed, though I haven't gone through
> everything rigorously and might be missing something.
> 
> FWIW, the meaning of the "decrypted" field in struct vmbus_gpadl is
> a bit abused, but it was already that way. In current code, it initially
> means "decryption needed". Then after the gpadl is created, it
> means "was decrypted" so that gpadl teardown will re-encrypt.
> But my suggested approach doesn't really make the abuse any worse.
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