linux-kernel - Re: [PATCH v2 08/16] x86/efi: Carrying hibernation key by setup data

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Message-ID: <20150821124026.GB3310@codeblueprint.co.uk>
Date:	Fri, 21 Aug 2015 13:40:26 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	"Lee, Chun-Yi" <joeyli.kernel@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Josh Boyer <jwboyer@...hat.com>,
	Vojtech Pavlik <vojtech@...e.cz>,
	Matt Fleming <matt.fleming@...el.com>,
	Jiri Kosina <jkosina@...e.cz>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	"Lee, Chun-Yi" <jlee@...e.com>
Subject: Re: [PATCH v2 08/16] x86/efi: Carrying hibernation key by setup data

On Tue, 11 Aug, at 02:16:28PM, Lee, Chun-Yi wrote:
> For forwarding hibernation key from EFI stub to boot kernel, this patch
> allocates setup data for carrying hibernation key, size and the status
> of efi operating.
 
This could do with some more information, and include that the key is
used to validate hibernate images.

But now that I think about it, is there a reason this patch hasn't
been merged with patch 6? The memory leak I mentioned in patch 6
becomes a non-issue in this one, so it would be good if these two
could be squashed together.
  
> Reviewed-by: Jiri Kosina <jkosina@...e.com>
> Tested-by: Jiri Kosina <jkosina@...e.com>
> Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
> ---
>  arch/x86/boot/compressed/eboot.c      | 26 +++++++++++++++++++++++---
>  arch/x86/include/uapi/asm/bootparam.h |  1 +
>  2 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index 463aa9b..c838d09 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -1394,18 +1394,22 @@ static void setup_hibernation_keys(struct boot_params *params)
>  {
>  	unsigned long key_size;
>  	unsigned long attributes;
> +	struct setup_data *setup_data, *hibernation_setup_data;
>  	struct hibernation_keys *keys;
> +	unsigned long size = 0;
>  	efi_status_t status;

One thing to be aware of is that eboot.c has mainly used the
"reverse-christmas-tree" style of variable declarations, with longer
lines first, and shorter ones following. I haven't mentioned it before
because none of your changes seemed to be too different (and it's not
a tree-wide convention), but the above setup_data line goes a bit too
far.

Could you try and keep them ordered, longest line first?

>  
>  	/* Allocate setup_data to carry keys */
> +	size = sizeof(struct setup_data) + sizeof(struct hibernation_keys);
>  	status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
> -				sizeof(struct hibernation_keys), &keys);
> +				size, &hibernation_setup_data);
>  	if (status != EFI_SUCCESS) {
>  		efi_printk(sys_table, "Failed to alloc mem for hibernation keys\n");
>  		return;
>  	}
>  
> -	memset(keys, 0, sizeof(struct hibernation_keys));
> +	memset(hibernation_setup_data, 0, size);
> +	keys = (struct hibernation_keys *) hibernation_setup_data->data;
>  
>  	status = efi_call_early(get_variable, HIBERNATION_KEY,
>  				&EFI_HIBERNATION_GUID, &attributes,
> @@ -1419,7 +1423,8 @@ static void setup_hibernation_keys(struct boot_params *params)
>  		if (status == EFI_SUCCESS) {
>  			efi_printk(sys_table, "Cleaned existing hibernation key\n");
>  			status = EFI_NOT_FOUND;
> -		}
> +		} else
> +			goto clean_fail;

Please add braces for the 'else' clause. Also, please include a
comment stating that the reason you jump to the label instead of
returning is so that the EFI status error code can be recorded in
hibernation_setup_data.

>  	}
>  
>  	if (status != EFI_SUCCESS) {
> @@ -1436,6 +1441,21 @@ static void setup_hibernation_keys(struct boot_params *params)
>  		if (status != EFI_SUCCESS)
>  			efi_printk(sys_table, "Failed to set hibernation key\n");
>  	}
> +
> +clean_fail:
> +	hibernation_setup_data->type = SETUP_HIBERNATION_KEYS;
> +	hibernation_setup_data->len = sizeof(struct hibernation_keys);
> +	hibernation_setup_data->next = 0;
> +	keys->hkey_status = efi_status_to_err(status);
> +
> +	setup_data = (struct setup_data *)params->hdr.setup_data;
> +	while (setup_data && setup_data->next)
> +		setup_data = (struct setup_data *)setup_data->next;
> +
> +	if (setup_data)
> +		setup_data->next = (unsigned long)hibernation_setup_data;
> +	else
> +		params->hdr.setup_data = (unsigned long)hibernation_setup_data;

This label name is a little confusing because you reach it both when
the EFI boot variable was successfully created and when a bogus EFI
variable failed to be deleted, i.e. it's not always reached because of
a failure.

How about 'setup' or simply 'out' ?

-- 
Matt Fleming, Intel Open Source Technology Center
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