linux-kernel - Re: [PATCH RESEND, v6 6/8] mailbox: mediatek: Add CMDQ secure mailbox driver

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Date: Wed, 29 May 2024 14:33:37 +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>, "chunkuang.hu@...nel.org"
	<chunkuang.hu@...nel.org>, "robh+dt@...nel.org" <robh+dt@...nel.org>,
	"krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>
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>,
	Jason-ch Chen (陳建豪)
	<Jason-ch.Chen@...iatek.com>, "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>, Shawn Sung (宋孝謙)
	<Shawn.Sung@...iatek.com>, Nancy Lin (林欣螢)
	<Nancy.Lin@...iatek.com>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.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 RESEND, v6 6/8] mailbox: mediatek: Add CMDQ secure mailbox
 driver

Hi CK,

On Tue, 2024-05-28 at 02:19 +0000, CK Hu (胡俊光) wrote:
> On Sun, 2024-05-26 at 22:44 +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.
> > 
> > TODO:
> > 1. Squash cmdq_sec_task_exec_work() into cmdq_sec_mbox_send_data().
> > 2. Call into TEE to query cookie instead of using shared memory in
> >    cmdq_sec_get_cookie().
> > 3. Register shared memory as command buffer instead of copying
> > normal
> >    command buffer to IWC shared memory.
> > 4. Use SOFTDEP to make cmdq_sec_probe later than OPTEE loaded and
> > then
> >    move cmdq_sec_session_init into cmdq_sec_probe().
> > 5. Remove timeout detection in cmdq_sec_session_send().
> > 
> > Signed-off-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
> > Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
> > ---
> 
> [snip]
> 
> > +static void cmdq_sec_irq_notify_work(struct work_struct
> > *work_item)
> > +{
> > +	struct cmdq_sec *cmdq = container_of(work_item, struct
> > cmdq_sec, irq_notify_work);
> > +	int i;
> > +
> > +	mutex_lock(&cmdq->exec_lock);
> > +
> > +	for (i = 0; i <= cmdq->pdata->secure_thread_nr; i++) {
> > +		struct cmdq_sec_thread *sec_thread = &cmdq-
> > >sec_thread[i];
> > +		u32 cookie = cmdq_sec_get_cookie(cmdq, sec_thread-
> > >idx);
> 
> I prefer to get current pa instead of cookie, but the current pa is
> mapped from secure packet pa to normal packet pa.
> If something wrong, normal world could know where GCE is stalled. And
> this is how normal thread irq handler does.
> We could use one method for both normal thread and secure thread.
> This is easier to maintain code.
> 
I'll try to change cookie to cmd buffer pa and query it from secure
world.

Regards,
Jason-JH.Lin

> Regards,
> CK
> 
> > +
> > +		if (cookie < sec_thread->wait_cookie || !sec_thread-
> > >task_cnt)
> > +			continue;
> > +
> > +		cmdq_sec_irq_handler(sec_thread, cookie, 0);
> > +	}
> > +
> > +	mutex_unlock(&cmdq->exec_lock);
> > +}
> > +