linux-kernel - Re: [PATCH v4 13/15] x86/sev: Take advantage of configfs visibility support in TSM

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Date: Fri, 26 Apr 2024 14:58:46 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Tom Lendacky <thomas.lendacky@....com>, <linux-kernel@...r.kernel.org>,
	<x86@...nel.org>, <linux-coco@...ts.linux.dev>, <svsm-devel@...onut-svsm.dev>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, "Peter
 Zijlstra" <peterz@...radead.org>, Dan Williams <dan.j.williams@...el.com>,
	Michael Roth <michael.roth@....com>, Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH v4 13/15] x86/sev: Take advantage of configfs visibility
 support in TSM

Tom Lendacky wrote:
> The TSM attestation report support provides multiple configfs attribute
> types (both for standard and binary attributes) to allow for additional
> attributes to be displayed for SNP as compared to TDX. With the ability
> to hide attributes via configfs, consoldate the multiple attribute groups
> into a single standard attribute group and a single binary attribute
> group. Modify the TDX support to hide the attributes that were previously
> "hidden" as a result of registering the selective attribute groups.
> 
> Co-developed-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  drivers/virt/coco/sev-guest/sev-guest.c |  3 +-
>  drivers/virt/coco/tdx-guest/tdx-guest.c | 29 ++++++++-
>  drivers/virt/coco/tsm.c                 | 82 ++++++++++++-------------
>  include/linux/tsm.h                     | 41 ++++++++++---
>  4 files changed, 102 insertions(+), 53 deletions(-)
[..]
> diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.c b/drivers/virt/coco/tdx-guest/tdx-guest.c
> index 1253bf76b570..964af57f345c 100644
> --- a/drivers/virt/coco/tdx-guest/tdx-guest.c
> +++ b/drivers/virt/coco/tdx-guest/tdx-guest.c
[..]
> @@ -249,6 +250,30 @@ static int tdx_report_new(struct tsm_report *report, void *data)
>  	return ret;
>  }
>  
> +static bool tdx_report_attr_visible(struct config_item *item,
> +				    struct configfs_attribute *attr, int n)
> +{
> +	switch (n) {
> +	case TSM_REPORT_GENERATION:
> +	case TSM_REPORT_PROVIDER:
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
> +static bool tdx_report_bin_attr_visible(struct config_item *item,
> +					struct configfs_bin_attribute *attr, int n)
> +{
> +	switch (n) {
> +	case TSM_REPORT_INBLOB:
> +	case TSM_REPORT_OUTBLOB:
> +		return true;
> +	}
> +
> +	return false;
> +}

Why do these callbacks need @item and @attr?

[..]
> +static bool tsm_report_is_visible(struct config_item *item,
> +				  struct configfs_attribute *attr, int n)

Per the comment on where to find the is_visible() callbacks for a given
item type, I expect the need to pass @item here goes away when this can
assume that there is only one way to have is_visible() invoked for
@attr, right?

Other than that, this conversion looks good to me.