linux-kernel - Re: [PATCH v7 8/8] drivers/node: Show in sysfs node's crypto capabilities

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Date:   Tue, 26 Apr 2022 09:16:02 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Martin Fernandez <martin.fernandez@...ypsium.com>
Cc:     linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, linux-mm@...ck.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        ardb@...nel.org, dvhart@...radead.org, andy@...radead.org,
        gregkh@...uxfoundation.org, rafael@...nel.org,
        akpm@...ux-foundation.org, daniel.gutson@...ypsium.com,
        hughsient@...il.com, alex.bazhaniuk@...ypsium.com,
        alison.schofield@...el.com, keescook@...omium.org
Subject: Re: [PATCH v7 8/8] drivers/node: Show in sysfs node's crypto
 capabilities

On Mon, Apr 25, 2022 at 02:15:26PM -0300, Martin Fernandez wrote:
> Show in each node in sysfs if its memory is able to do be encrypted by
> the CPU, ie. if all its memory is marked with EFI_MEMORY_CPU_CRYPTO in
> the EFI memory map.
> 
> Signed-off-by: Martin Fernandez <martin.fernandez@...ypsium.com>
> ---
>  Documentation/ABI/testing/sysfs-devices-node | 10 ++++++++++
>  drivers/base/node.c                          | 10 ++++++++++
>  2 files changed, 20 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-devices-node
> 
> diff --git a/Documentation/ABI/testing/sysfs-devices-node b/Documentation/ABI/testing/sysfs-devices-node
> new file mode 100644
> index 000000000000..5fd5dc7fc2eb
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-node
> @@ -0,0 +1,10 @@
> +What:		/sys/devices/system/node/nodeX/crypto_capable
> +Date:		April 2022
> +Contact:	Martin Fernandez <martin.fernandez@...ypsium.com>
> +Users:		fwupd (https://fwupd.org)
> +Description:
> +		This value is 1 if all system memory in this node is
> +		marked with EFI_MEMORY_CPU_CRYPTO, indicating that the
> +		system memory is capable of being protected with the
> +		CPU’s memory cryptographic capabilities. It is 0
> +		otherwise.

I understand that currently this feature is only for x86, but if non-EFI
architectures will start using MEMBLOCK_CRYPTO_CAPABLE, the sysfs attribute
for will be relevant form them as well.

How about
	This value is 1 if all system memory in this node is capable of
	being protected with the CPU's memory cryptographic capabilities.
	It is 0 otherwise.
	On EFI systems the node will be marked with EFI_MEMORY_CPU_CRYPTO.

> \ No newline at end of file
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index ec8bb24a5a22..1df15ea03c27 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -560,11 +560,21 @@ static ssize_t node_read_distance(struct device *dev,
>  }
>  static DEVICE_ATTR(distance, 0444, node_read_distance, NULL);
>  
> +static ssize_t crypto_capable_show(struct device *dev,
> +				   struct device_attribute *attr, char *buf)
> +{
> +	struct pglist_data *pgdat = NODE_DATA(dev->id);
> +
> +	return sysfs_emit(buf, "%d\n", pgdat->crypto_capable);
> +}
> +static DEVICE_ATTR_RO(crypto_capable);
> +
>  static struct attribute *node_dev_attrs[] = {
>  	&dev_attr_meminfo.attr,
>  	&dev_attr_numastat.attr,
>  	&dev_attr_distance.attr,
>  	&dev_attr_vmstat.attr,
> +	&dev_attr_crypto_capable.attr,
>  	NULL
>  };
>  
> -- 
> 2.30.2
> 

-- 
Sincerely yours,
Mike.