linux-kernel - Re: [PATCH v2 2/2] tpm: Add reserved memory event log

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Date:   Sat, 21 Jan 2023 00:13:09 +0000
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Eddie James <eajames@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        jgg@...pe.ca, peterhuewe@....de
Subject: Re: [PATCH v2 2/2] tpm: Add reserved memory event log

On Fri, Jan 13, 2023 at 10:10:17AM -0600, Eddie James wrote:
> Some platforms may desire to pass the event log up to linux in the
> form of a reserved memory region. Add support for this in the TPM
> core to find the reserved memory region and map it.
> 
> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
> ---
>  drivers/char/tpm/eventlog/of.c | 38 +++++++++++++++++++++++++++++++++-
>  1 file changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
> index 741ab2204b11..c815cadf00a4 100644
> --- a/drivers/char/tpm/eventlog/of.c
> +++ b/drivers/char/tpm/eventlog/of.c
> @@ -12,12 +12,48 @@
>  
>  #include <linux/device.h>
>  #include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_reserved_mem.h>
>  #include <linux/tpm_eventlog.h>
>  
>  #include "../tpm.h"
>  #include "common.h"
>  
> +static int tpm_read_log_memory_region(struct tpm_chip *chip)
> +{
> +	struct device_node *node;
> +	struct resource res;
> +	int rc;
> +
> +	node = of_parse_phandle(chip->dev.parent->of_node, "memory-region", 0);
> +	if (!node) {
> +		dev_info(&chip->dev, "no phandle\n");
> +		return -ENODEV;
> +	}
> +
> +	rc = of_address_to_resource(node, 0, &res);
> +	of_node_put(node);
> +	if (rc) {
> +		dev_info(&chip->dev, "no mem\n");
> +		return rc;
> +	}
> +
> +	chip->log.bios_event_log = devm_memremap(&chip->dev, res.start, resource_size(&res),
> +						 MEMREMAP_WB);
> +	if (!chip->log.bios_event_log) {
> +		dev_info(&chip->dev, "err memremap\n");
> +		return -ENOMEM;
> +	}
> +
> +	chip->log.bios_event_log_end = chip->log.bios_event_log + resource_size(&res);
> +
> +	return chip->flags & TPM_CHIP_FLAG_TPM2 ? EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 :
> +		EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> +}
> +
>  int tpm_read_log_of(struct tpm_chip *chip)
>  {
>  	struct device_node *np;
> @@ -39,7 +75,7 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	sizep = of_get_property(np, "linux,sml-size", NULL);
>  	basep = of_get_property(np, "linux,sml-base", NULL);
>  	if (sizep == NULL && basep == NULL)
> -		return -ENODEV;
> +		return tpm_read_log_memory_region(chip);
>  	if (sizep == NULL || basep == NULL)
>  		return -EIO;
>  
> -- 
> 2.31.1
> 

I would CC this to linux-devicetree.

BR, Jarkko