[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <356d4ad1-f7d8-b8ff-3b63-819a64bf5b9f@intel.com>
Date: Mon, 12 Sep 2022 14:41:56 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Jacob Pan <jacob.jun.pan@...el.com>,
Ashok Raj <ashok_raj@...ux.intel.com>
Cc: "Kirill A. Shutemov" <kirill@...temov.name>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
Kostya Serebryany <kcc@...gle.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Taras Madan <tarasmadan@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
"H . J . Lu" <hjl.tools@...il.com>,
Andi Kleen <ak@...ux.intel.com>,
Rick Edgecombe <rick.p.edgecombe@...el.com>,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCHv8 00/11] Linear Address Masking enabling
On 9/12/22 13:39, Jacob Pan wrote:
>>> + if (pasid_valid(mm->pasid) && !forced) {
> I don't think this works since we have lazy pasid free. for example,
> after all the devices did sva_unbind, mm->pasid we'll remain valid until
> mmdrop(). LAM should be supported in this case.
Nah, it works fine.
It just means that the rules are "you can't do LAM if your process
*EVER* got a PASID" instead of "you can't do LAM if you are actively
using your PASID".
We knew that PASID use would be a one-way trip for a process when we
moved to the simplified implementation. This is just more fallout from
that. It's fine.
> Perhaps, we could introduce another prctl flag for SVA, PR_GET_SVA?
> Both iommu driver and LAM can set/query the flag. LAM applications may not
> be the only ones want to know if share virtual addressing is on.
I don't think it's a good idea to add yet more UABI around this issue.
Won't the IOMMU folks eventually get their hardware in line with LAM?
Isn't this situation temporary?
Powered by blists - more mailing lists