linux-kernel - Re: [PATCH v3] tpm, tpm_crb: fix unaligned read of the command buffer address

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Message-ID: <20150915172227.GA24173@obsidianresearch.com>
Date:	Tue, 15 Sep 2015 11:22:27 -0600
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	Peter Huewe <peterhuewe@....de>,
	Marcel Selhorst <tpmdd@...horst.net>
Subject: Re: [PATCH v3] tpm, tpm_crb: fix unaligned read of the command
 buffer address

On Tue, Sep 15, 2015 at 08:05:40PM +0300, Jarkko Sakkinen wrote:
> The command buffer address must be read with exactly two 32-bit reads.
> Otherwise, on some HW platforms, it seems that HW will abort the read
> operation, which causes CPU to fill the read bytes with 1's. Therefore,
> we cannot rely on memcpy_fromio() but must call ioread32() two times
> instead.
> 
> Also, this matches the PC Client Platform TPM Profile specification,
> which defines command buffer address with two 32-bit fields.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
>  drivers/char/tpm/tpm_crb.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index b4564b6..c09b370 100644
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -68,7 +68,8 @@ struct crb_control_area {
>  	u32 int_enable;
>  	u32 int_sts;
>  	u32 cmd_size;
> -	u64 cmd_pa;
> +	u32 cmd_pa_low;
> +	u32 cmd_pa_high;
>  	u32 rsp_size;
>  	u64 rsp_pa;

What about rsp_pa?

>  } __packed;

As I mentioned, drop the __packed.

Otherwise:

Reviewed-By: Jason Gunthorpe <jgunthorpe@...idianresearch.com>

Jason
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