Re: [PATCH v5 11/17] platform/x86/amd/pmf: Add capability to sideload of policy binary

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Fri, 17 Nov 2023, Shyam Sundar S K wrote:

> A policy binary is OS agnostic, and the same policies are expected to work
> across the OSes.  At times it becomes difficult to debug when the policies
> inside the policy binaries starts to misbehave. Add a way to sideload such
> policies independently to debug them via a debugfs entry.
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
> ---

> diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x86/amd/pmf/tee-if.c
> index 5f10e5c6335e..f73663c629fe 100644
> --- a/drivers/platform/x86/amd/pmf/tee-if.c
> +++ b/drivers/platform/x86/amd/pmf/tee-if.c

> +#ifdef CONFIG_AMD_PMF_DEBUG
> +static ssize_t amd_pmf_get_pb_data(struct file *filp, const char __user *buf,
> +				   size_t length, loff_t *pos)
> +{
> +	struct amd_pmf_dev *dev = filp->private_data;
> +	int ret;
> +
> +	/* Policy binary size cannot exceed POLICY_BUF_MAX_SZ */
> +	if (length > POLICY_BUF_MAX_SZ || length == 0)
> +		return -EINVAL;
> +
> +	dev->policy_sz = length;
> +	if (copy_from_user(dev->policy_buf, buf, dev->policy_sz))
> +		return -EFAULT;
> +
> +	ret = amd_pmf_start_policy_engine(dev);

Is this call safe against concurrent invocations from two racing writes?

Other than that, this change looked fine.

> +	if (ret)
> +		return -EINVAL;
> +
> +	return length;
> +}


-- 
 i.