linux-kernel - Re: [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code

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Message-ID: <20201116201711.GE1131@zn.tnic>
Date:   Mon, 16 Nov 2020 21:17:11 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Alexandre Chartre <alexandre.chartre@...cle.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, dave.hansen@...ux.intel.com, luto@...nel.org,
        peterz@...radead.org, linux-kernel@...r.kernel.org,
        thomas.lendacky@....com, jroedel@...e.de, konrad.wilk@...cle.com,
        jan.setjeeilers@...cle.com, junaids@...gle.com, oweisse@...gle.com,
        rppt@...ux.vnet.ibm.com, graf@...zon.de, mgross@...ux.intel.com,
        kuzuno@...il.com
Subject: Re: [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code

On Mon, Nov 16, 2020 at 03:47:36PM +0100, Alexandre Chartre wrote:
> This RFC proposes to defer the PTI CR3 switch until we reach C code.
> The benefit is that this simplifies the assembly entry code, and make
> the PTI CR3 switch code easier to understand. This also paves the way
> for further possible projects such an easier integration of Address
> Space Isolation (ASI), or the possibilily to execute some selected
> syscall or interrupt handlers without switching to the kernel page-table

What for? What is this going to be used for in the end?

> (and thus avoid the PTI page-table switch overhead).

Overhead of how much? Why do we care?

What is the big picture justfication for this diffstat

>  21 files changed, 874 insertions(+), 314 deletions(-)

and the diffstat for the ASI enablement?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette