linux-kernel - Re: [RFC v2 00/27] Kernel Address Space Isolation

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Date:   Thu, 11 Jul 2019 15:38:46 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Alexandre Chartre <alexandre.chartre@...cle.com>,
        pbonzini@...hat.com, rkrcmar@...hat.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        kvm@...r.kernel.org, x86@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     konrad.wilk@...cle.com, jan.setjeeilers@...cle.com,
        liran.alon@...cle.com, jwadams@...gle.com, graf@...zon.de,
        rppt@...ux.vnet.ibm.com
Subject: Re: [RFC v2 00/27] Kernel Address Space Isolation

On 7/11/19 7:25 AM, Alexandre Chartre wrote:
> - Kernel code mapped to the ASI page-table has been reduced to:
>   . the entire kernel (I still need to test with only the kernel text)
>   . the cpu entry area (because we need the GDT to be mapped)
>   . the cpu ASI session (for managing ASI)
>   . the current stack
> 
> - Optionally, an ASI can request the following kernel mapping to be added:
>   . the stack canary
>   . the cpu offsets (this_cpu_off)
>   . the current task
>   . RCU data (rcu_data)
>   . CPU HW events (cpu_hw_events).

I don't see the per-cpu areas in here.  But, the ASI macros in
entry_64.S (and asi_start_abort()) use per-cpu data.

Also, this stuff seems to do naughty stuff (calling C code, touching
per-cpu data) before the PTI CR3 writes have been done.  But, I don't
see anything excluding PTI and this code from coexisting.