linux-kernel - Re: [PATCH RFC v6 05/26] nova-core: mm: Add support to use PRAMIN windows to write to VRAM

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Message-ID:
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Date: Fri, 23 Jan 2026 07:59:01 -0500
From: Joel Fernandes <joelagnelf@...dia.com>
To: Zhi Wang <zhiw@...dia.com>
Cc: linux-kernel@...r.kernel.org,
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Subject: Re: [PATCH RFC v6 05/26] nova-core: mm: Add support to use PRAMIN windows to write to VRAM

On Fri, 23 Jan 2026 12:13:43 +0200, Zhi Wang wrote:
> Thanks so much for the work and the discussion. It is super important
> efforts for me to move on for the vGPU work. :)

Great!

> As we discussed, the concurrency matters most when booting multiple vGPUs.
> At that time, the concurrency happens at:
>
> 1) Allocating GPU memory chunks
> 2) Reserving GPU channels
> 3) Mapping GPU memory to BAR1 page table

Yes all these are already covered from a concurrency PoV by the v6.

> I can see you are thinking of fine-granularity locking scheme, which I
> think is the right direction to go. I agreed with the above two locks.

Cool!

> However for 3), We need to have one there as well beside the above two
> locks. Have you already had one in the GPU VA allocator?

Currently for mapping Bar pages, you need a mutable reference to BarUser.
For the future, when we have multiple channels sharing the same va space,
it will still be protected because the va space allocator (virt_buddy)
already has internal locking. And for each map_page, it is protected as
well. So I believe that should also be covered. Thanks for checking.

> If yes, the above two locks should be good enough so far. IMO.

Ok, thanks for checking.

--
Joel Fernandes