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

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Message-ID: <20151009105812.GB8120@intel.com>
Date:	Fri, 9 Oct 2015 13:58:12 +0300
From:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Cc:	Peter Huewe <peterhuewe@....de>,
	Marcel Selhorst <tpmdd@...horst.net>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Subject: Re: [PATCH v3] tpm, tpm_crb: fix unaligned read of the command
 buffer address

Hi

This would desperately neeed Tested-by's (with Haswell PTT).

/Jarkko

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
> --- a/drivers/char/tpm/tpm_crb.c
> +++ 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;
>  } __packed;
> @@ -263,8 +264,8 @@ static int crb_acpi_add(struct acpi_device *device)
>  		return -ENOMEM;
>  	}
>  
> -	memcpy_fromio(&pa, &priv->cca->cmd_pa, 8);
> -	pa = le64_to_cpu(pa);
> +	pa = ((u64) le32_to_cpu(ioread32(&priv->cca->cmd_pa_high)) << 32) +
> +		(u64) le32_to_cpu(ioread32(&priv->cca->cmd_pa_low));
>  	priv->cmd = devm_ioremap_nocache(dev, pa,
>  					 ioread32(&priv->cca->cmd_size));
>  	if (!priv->cmd) {
> -- 
> 2.5.0
> 
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