linux-kernel - Re: [PATCH] platform/x86/amd/pmf: Fix a potential race with policy binary sideload

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Date: Mon, 19 Feb 2024 13:40:19 +0100
From: Hans de Goede <hdegoede@...hat.com>
To: Mario Limonciello <mario.limonciello@....com>, Shyam-sundar.S-k@....com
Cc: platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform/x86/amd/pmf: Fix a potential race with policy
 binary sideload

Hi,

On 2/17/24 02:56, Mario Limonciello wrote:
> The debugfs `update_policy` file is created before
> amd_pmf_start_policy_engine() has completed, and thus there could be
> a possible (albeit unlikely) race between sideloading a policy and the
> BIOS policy getting setup.
> 
> Move the debugfs file creation after all BIOS policy is setup.
> 
> Fixes: 10817f28e533 ("platform/x86/amd/pmf: Add capability to sideload of policy binary")
> Reported-by: Hans de Goede <hdegoede@...hat.com>
> Closes: https://lore.kernel.org/platform-driver-x86/15df7d02-b0aa-457a-954a-9d280a592843@redhat.com/T/#m2c445f135e5ef9b53184be7fc9df84e15f89d4d9
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

I will include this patch in my next fixes pull-req to Linus
for the current kernel development cycle.

Regards,

Hans

> ---
>  drivers/platform/x86/amd/pmf/tee-if.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x86/amd/pmf/tee-if.c
> index 4f74de680654..8527dca9cf56 100644
> --- a/drivers/platform/x86/amd/pmf/tee-if.c
> +++ b/drivers/platform/x86/amd/pmf/tee-if.c
> @@ -456,8 +456,6 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
>  	memcpy(dev->policy_buf, dev->policy_base, dev->policy_sz);
>  
>  	amd_pmf_hex_dump_pb(dev);
> -	if (pb_side_load)
> -		amd_pmf_open_pb(dev, dev->dbgfs_dir);
>  
>  	dev->prev_data = kzalloc(sizeof(*dev->prev_data), GFP_KERNEL);
>  	if (!dev->prev_data)
> @@ -467,6 +465,9 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
>  	if (ret)
>  		goto error;
>  
> +	if (pb_side_load)
> +		amd_pmf_open_pb(dev, dev->dbgfs_dir);
> +
>  	return 0;
>  
>  error: