linux-kernel - Re: [RFC v2 02/26] mm/asi: Abort isolation on interrupt, exception and context switch

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Date:   Thu, 11 Jul 2019 22:41:59 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>,
        Andi Kleen <andi@...stfloor.org>
Cc:     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, 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 02/26] mm/asi: Abort isolation on interrupt, exception
 and context switch



On 7/11/19 10:17 PM, Mike Rapoport wrote:
> On Thu, Jul 11, 2019 at 01:11:43PM -0700, Andi Kleen wrote:
>> Alexandre Chartre <alexandre.chartre@...cle.com> writes:
>>>   	jmp	paranoid_exit
>>> @@ -1182,6 +1196,16 @@ ENTRY(paranoid_entry)
>>>   	xorl	%ebx, %ebx
>>>   
>>>   1:
>>> +#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
>>> +	/*
>>> +	 * If address space isolation is active then abort it and return
>>> +	 * the original kernel CR3 in %r14.
>>> +	 */
>>> +	ASI_START_ABORT_ELSE_JUMP 2f
>>> +	movq	%rdi, %r14
>>> +	ret
>>> +2:
>>> +#endif
>>
>> Unless I missed it you don't map the exception stacks into ASI, so it
>> has likely already triple faulted at this point.
> 
> The exception stacks are in the CPU entry area, aren't they?
>   

That's my understanding, stacks come from tss in the CPU entry area and
the CPU entry area is part for the core ASI mappings (see patch 15/26).

alex.