linux-kernel - Re: [PATCH] crypto: ccp: Add support for SEV-ES to the PSP driver

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Message-ID: <c609bc22-735a-0db9-3367-0713898707ab@amd.com>
Date:   Tue, 21 Apr 2020 08:15:16 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        Herbert Xu <herbert@...dor.apana.org.au>,
        David Miller <davem@...emloft.net>,
        Borislav Petkov <bp@...en8.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH] crypto: ccp: Add support for SEV-ES to the PSP driver

On 4/21/20 7:33 AM, Joerg Roedel wrote:
> Hi Tom,
> 
> On Mon, Apr 20, 2020 at 02:54:58PM -0500, Tom Lendacky wrote:
>>   static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
>>   {
>>   	struct sev_device *sev = psp_master->sev_data;
>> @@ -214,6 +226,21 @@ static int __sev_platform_init_locked(int *error)
>>   	if (sev->state == SEV_STATE_INIT)
>>   		return 0;
>>   
>> +	if (sev_es_tmr) {
>> +		u64 tmr_pa;
>> +
>> +		/*
>> +		 * Do not include the encryption mask on the physical
>> +		 * address of the TMR (firmware should clear it anyway).
>> +		 */
>> +		tmr_pa = __pa(sev_es_tmr);
>> +		tmr_pa = ALIGN(tmr_pa, SEV_ES_TMR_ALIGN);
> 
> No need to manually align the region, see below.
> 
>> +	/* Obtain the TMR memory area for SEV-ES use */
>> +	tmr_page = alloc_pages(GFP_KERNEL, get_order(SEV_ES_TMR_LEN));
>> +	if (tmr_page) {
>> +		sev_es_tmr = page_address(tmr_page);
>> +	} else {
>> +		sev_es_tmr = NULL;
>> +		dev_warn(sev->dev,
>> +			 "SEV: TMR allocation failed, SEV-ES support unavailable\n");
>> +	}
> 
> This allocates a 2M region where 1M is needed. The page allocator gives
> you naturally aligned region for any allocation order, so when you
> allocate 1M, it will automatically be 1M aligned.

Ah, I did not realize that. I'll update the patch to allocate just 1M then.

Thanks,
Tom

> 
> Other than that this patch looks good to me.
> 
> Regards,
> 
> 	Joerg
>