linux-kernel - Re: [PATCH v3 10/14] configfs-tsm: Allow the privlevel

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Date: Tue, 16 Apr 2024 10:23:23 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Dan Williams <dan.j.williams@...el.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>, Michael Roth <michael.roth@....com>,
 Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH v3 10/14] configfs-tsm: Allow the privlevel_floor
 attribute to be updated

On 4/15/24 23:55, Dan Williams wrote:
> Tom Lendacky wrote:
>> With the introduction of an SVSM, Linux will be running at a non-zero
>> VMPL. Any request for an attestation report at a higher priviledge VMPL
>> than what Linux is currently running will result in an error. Allow for
>> the privlevel_floor attribute to be updated dynamically so that the
>> attribute may be set dynamically.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> ---
>>   drivers/virt/coco/sev-guest/sev-guest.c | 5 ++++-
>>   include/linux/tsm.h                     | 2 +-
>>   2 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
>> index 1ff897913bf4..bba6531cb606 100644
>> --- a/drivers/virt/coco/sev-guest/sev-guest.c
>> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
>> @@ -885,7 +885,7 @@ static int sev_report_new(struct tsm_report *report, void *data)
>>   	return 0;
>>   }
>>   
>> -static const struct tsm_ops sev_tsm_ops = {
>> +static struct tsm_ops sev_tsm_ops = {
>>   	.name = KBUILD_MODNAME,
>>   	.report_new = sev_report_new,
>>   };
>> @@ -972,6 +972,9 @@ static int __init sev_guest_probe(struct platform_device *pdev)
>>   	snp_dev->input.resp_gpa = __pa(snp_dev->response);
>>   	snp_dev->input.data_gpa = __pa(snp_dev->certs_data);
>>   
>> +	/* Set the privlevel_floor attribute based on the current VMPL */
>> +	sev_tsm_ops.privlevel_floor = snp_get_vmpl();
> 
> Why is this not vmpck_id?

Good catch, this probably should be pulled out separately and submitted 
as a Fixes: against the current support. If you think it's important 
enough, I can do that and put this at the beginning of the series. Or I 
can just modify this to use the vmpck_id value. Any preference?

Thanks,
Tom