lkml.org 
[lkml]   [2022]   [Sep]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCHv8 00/11] Linear Address Masking enabling
Hi Dave,

On Mon, 12 Sep 2022 14:41:56 -0700, Dave Hansen <dave.hansen@intel.com>
wrote:

> 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".
Sure it works if you change the rules, but this case need to documented.

>
> 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.
>
Is LAM also a one-way trip?

> > 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?


Thanks,

Jacob

\
 
 \ /
  Last update: 2022-09-13 00:52    [W:0.088 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site