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From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Tue, 27 Feb 2024 14:59:23 +0200 (EET)
To: Armin Wolf <W_Armin@gmx.de>
cc: Shyam-sundar.S-k@amd.com, 
    Mika Westerberg <mika.westerberg@linux.intel.com>, 
    sathyanarayanan.kuppuswamy@linux.intel.com, 
    Hans de Goede <hdegoede@redhat.com>, platform-driver-x86@vger.kernel.org, 
    LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] platform/x86/amd/pmf: Do not use readl() for
 policy buffer access
In-Reply-To: <20240223163901.13504-2-W_Armin@gmx.de>
Message-ID: <e2b81849-3435-3efb-f2da-b74ac7f99a50@linux.intel.com>
References: <20240223163901.13504-1-W_Armin@gmx.de> <20240223163901.13504-2-W_Armin@gmx.de>
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On Fri, 23 Feb 2024, Armin Wolf wrote:

> The policy buffer is allocated using normal memory allocation
> functions, so readl() should not be used on it.
> 
> Use get_unaligned_le32() instead.
> 
> Compile-tested only.
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
>  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 16973bebf55f..3220b6580270 100644
> --- a/drivers/platform/x86/amd/pmf/tee-if.c
> +++ b/drivers/platform/x86/amd/pmf/tee-if.c
> @@ -11,6 +11,7 @@
>  #include <linux/debugfs.h>
>  #include <linux/tee_drv.h>
>  #include <linux/uuid.h>
> +#include <asm/unaligned.h>
>  #include "pmf.h"
> 
>  #define MAX_TEE_PARAM	4
> @@ -249,8 +250,8 @@ static int amd_pmf_start_policy_engine(struct amd_pmf_dev *dev)
>  	u32 cookie, length;
>  	int res;
> 
> -	cookie = readl(dev->policy_buf + POLICY_COOKIE_OFFSET);
> -	length = readl(dev->policy_buf + POLICY_COOKIE_LEN);
> +	cookie = get_unaligned_le32(dev->policy_buf + POLICY_COOKIE_OFFSET);
> +	length = get_unaligned_le32(dev->policy_buf + POLICY_COOKIE_LEN);

I don't understand you need _unaligned_ here, the offsets should be dword 
aligned, no?

#define POLICY_COOKIE_OFFSET      0x10
#define POLICY_COOKIE_LEN         0x14

-- 
 i.