Re: [PATCH v3] lib: sbi: Enable Ssqosid Ext using mstateen0

From: "Radim Krčmář" <rkrcmar@ventanamicro.com>
To: <cp0613@linux.alibaba.com>
Cc: <anup@brainfault.org>, <guoren@kernel.org>,
	<opensbi@lists.infradead.org>,
	"opensbi" <opensbi-bounces@lists.infradead.org>
Subject: Re: [PATCH v3] lib: sbi: Enable Ssqosid Ext using mstateen0
Date: Tue, 11 Nov 2025 11:18:21 +0100	[thread overview]
Message-ID: <DE5SEKPHV34G.18XMB4JDT7M0O@ventanamicro.com> (raw)
In-Reply-To: <20251111094938.1492-1-cp0613@linux.alibaba.com>

2025-11-11T17:49:36+08:00, <cp0613@linux.alibaba.com>:
> On 2025-11-10 02:41 PM, Radim Krčmář wrote:
>> >                                         so there is no need to consider the execution
>> > situation in M-mode, it is only necessary to enable the relevant permissions.
>> 
>> The execution of M-mode is affected by srmcfg, so we have to be
>> extremely careful about isolation in opensbi too, especially when
>> juggling multiple domains.
>> 
>> (I think we might be fine now, but having opensbi switch to a srmcfg
>>  that isn't controlled by S-mode will result in a lot less headaches...)
>> 
>> Thanks.
>
> Indeed, strictly speaking, the execution of M-mode is also affected by srmcfg.
> When dealing with multiple domains, attention needs to be paid to isolation and
> context switching issues. I understand your point of view.
>
> However, I wonder if it could be done in a later stage of the work, because there
> is currently a draft specification smmtt[1] that is also related to this. This
> extension involves multiple Supervisor Domains, and at this time, it is necessary
> to implement context switching of srmcfg between different domains.

I agree that we can return to that issue later, as it's not clearly
buggy for now.  For this patch, I would just like to fix the condition.

Thanks.

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