linux-kernel - Re: [PATCH v3 8/9] mailbox: mediatek: Add CMDQ secure mailbox driver

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Date: Wed, 3 Jan 2024 06:51:34 +0000
From: Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com>
To: CK Hu (胡俊光) <ck.hu@...iatek.com>,
	"jassisinghbrar@...il.com" <jassisinghbrar@...il.com>,
	"matthias.bgg@...il.com" <matthias.bgg@...il.com>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>, "robh+dt@...nel.org"
	<robh+dt@...nel.org>, "krzysztof.kozlowski+dt@...aro.org"
	<krzysztof.kozlowski+dt@...aro.org>, "chunkuang.hu@...nel.org"
	<chunkuang.hu@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	Singo Chang (張興國) <Singo.Chang@...iatek.com>,
	Johnson Wang (王聖鑫) <Johnson.Wang@...iatek.com>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Jason-ch Chen (陳建豪)
	<Jason-ch.Chen@...iatek.com>, Shawn Sung (宋孝謙)
	<Shawn.Sung@...iatek.com>, "mchehab@...nel.org" <mchehab@...nel.org>,
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
	"conor+dt@...nel.org" <conor+dt@...nel.org>,
	Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 8/9] mailbox: mediatek: Add CMDQ secure mailbox driver

On Thu, 2023-12-28 at 02:02 +0000, CK Hu (胡俊光) wrote:
> On Wed, 2023-12-27 at 06:13 +0000, Jason-JH Lin (林睿祥) wrote:
> > Hi CK,
> > 
> > Thanks for the reviews.
> > 
> > On Tue, 2023-12-26 at 06:46 +0000, CK Hu (胡俊光) wrote:
> > > Hi, Jason:
> > > 
> > > On Fri, 2023-12-22 at 12:52 +0800, Jason-JH.Lin wrote:
> > > > To support secure video path feature, GCE have to read/write
> > > > registgers
> > > > in the secure world. GCE will enable the secure access
> > > > permission
> > > > to
> > > > the
> > > > HW who wants to access the secure content buffer.
> > > > 
> > > > Add CMDQ secure mailbox driver to make CMDQ client user is able
> > > > to
> > > > sending their HW settings to the secure world. So that GCE can
> > > > execute
> > > > all instructions to configure HW in the secure world.
> > > > 
> > > > Signed-off-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
> > > > ---
> > > 
> > > [snip]
> > > 
> > > > +
> > > > +static int cmdq_sec_session_init(struct cmdq_sec_context
> > > > *context)
> > > > +{
> > > > +	int err = 0;
> > > > +
> > > > +	if (context->state >= IWC_SES_OPENED) {
> > > > +		pr_debug("session opened:%u", context->state);
> > > > +		return 0;
> > > > +	}
> > > > +
> > > > +	switch (context->state) {
> > > > +	case IWC_INIT:
> > > > +		err = cmdq_sec_init_context(&context->tee_ctx);
> > > > +		if (err)
> > > > +			return err;
> > > > +		context->state = IWC_CONTEXT_INITED;
> > > > +	fallthrough;
> > > > +	case IWC_CONTEXT_INITED:
> > > > +		if (context->iwc_msg) {
> > > > +			pr_err("iwcMessage not NULL:%p",
> > > > context-
> > > > > iwc_msg);
> > > > 
> > > > +			return -EINVAL;
> > > > +		}
> > > > +
> > > > +		err = cmdq_sec_allocate_wsm(&context->tee_ctx,
> > > > &context->iwc_msg,
> > > > +					    sizeof(struct
> > > > iwc_cmdq_message_t));
> > > > +		if (err)
> > > > +			return err;
> > > > +
> > > > +		context->state = IWC_WSM_ALLOCATED;
> > > > +	fallthrough;
> > > 
> > > Squash cmdq_sec_session_init() into cmdq_sec_mbox_of_xlate() and
> > > drop
> > > the context->state.
> > > 
> > > Regards,
> > > CK
> > > 
> > 
> > cmdq_sec_session_init() is called in the first
> > cmdq_sec_task_submit().
> > It means we don't need to connect a session to TEE or allocate
> > share
> > memory if no one submit secure task.
> > 
> > On the other hand, optee may load slower than cmdq secure driver.
> > If
> > we
> > move it to xlate secure session may init fail.
> 
> For driver probe dependency, you could refer to [1]. I would like
> resource allocation and free to be symmetric. So maybe allocate/free
> in
> probe/remove or starup/shutdown. If the secure driver is probed, I
> think it would finally allocate secure resource. So later allocation
> has no much benefit and make code more complicated. 
> 
> [1] 
> 
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/gpu/drm/mediatek?h=next-20231222&id=c8048dd0b07df68724805254b9e994d99e9a7af4
> 
> Regards,
> CK
> 
> 

I've tried to move that to mbox startup, but I got an error when
tee_shm_register_kernel_buf().

I'll try to fix it first, then try your SOFTDEP method. Thanks!

Regards,
Jason-JH.Lin

> > 
> > Regards,
> > Jason-JH.Lin