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

From: Stefan Berger <stefanb@linux.ibm.com>
To: Eddie James <eajames@linux.ibm.com>, linux-integrity@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, jgg@ziepe.ca, jarkko@kernel.org,
	peterhuewe@gmx.de
Subject: Re: [PATCH v2 2/2] tpm: Add reserved memory event log
Date: Wed, 18 Jan 2023 10:01:16 -0500	[thread overview]
Message-ID: <adced60c-3abe-8f14-9146-e15cee98d5ee@linux.ibm.com> (raw)
In-Reply-To: <3161efa3-2e72-bcc4-95d9-736a55f6535e@linux.ibm.com>

On 1/18/23 09:49, Eddie James wrote:
> 
> On 1/18/23 07:27, Stefan Berger wrote:
>>
>>
>> On 1/13/23 11:10, Eddie James wrote:
>>> Some platforms may desire to pass the event log up to linux in the
>>
>> Which platforms are these that work like this?
> 
> 
> Platforms booting from U-Boot without EFI. So at the moment, IBM's OpenBMC systems hope to use this.

It may be worth to mention this in the patch description in case someone wonders which
systems would take that path.

    Stefan
> 
> Thanks,
> 
> Eddie
> 
> 
>>
>>    Stefan
>>
>>> 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@linux.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;