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From: Nadav Amit <nadav.amit@gmail.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Flushing user entries for kernel mappings in x86
Date: Wed, 29 Aug 2018 01:37:55 -0700	[thread overview]
Message-ID: <7EDEB913-E4F8-481F-93D3-EE158641A366@gmail.com> (raw)
In-Reply-To: <CALCETrWy3v-DiCNJs=wkym_q4U07-mtmEqy1YgMvAJ8AOT8MJQ@mail.gmail.com>

at 8:45 PM, Andy Lutomirski <luto@kernel.org> wrote:

> On Tue, Aug 28, 2018 at 6:46 PM, Nadav Amit <nadav.amit@gmail.com> wrote:
>> Hello Andy,
>> 
>> Is there a reason for __flush_tlb_one_kernel() to flush the PTE not only in
>> the kernel address space, but also in the user one (as part of
>> __flush_tlb_one_user)? [ I obviously regard the case when PTI is on ].
> 
> In most cases, probably not, but it's fairly cheap, I think.  And it
> makes it so that we're okay if the TLB entry we're flushing is used by
> the entry code.

Thanks. I assumed that’s the case. I don’t know how cheap they are
(especially if INVPCID is not supported) but I guess they are not that
frequent.


      reply	other threads:[~2018-08-29  8:38 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-29  1:46 Nadav Amit
2018-08-29  3:45 ` Andy Lutomirski
2018-08-29  8:37   ` Nadav Amit [this message]

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