linux-kernel - Re: [PATCH v9 06/24] virt: sev-guest: Simplify VMPCK and sequence number assignments

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Date: Wed, 19 Jun 2024 20:50:22 +0530
From: "Nikunj A. Dadhania" <nikunj@....com>
To: Tom Lendacky <thomas.lendacky@....com>, linux-kernel@...r.kernel.org,
 bp@...en8.de, x86@...nel.org, kvm@...r.kernel.org
Cc: mingo@...hat.com, tglx@...utronix.de, dave.hansen@...ux.intel.com,
 pgonda@...gle.com, seanjc@...gle.com, pbonzini@...hat.com
Subject: Re: [PATCH v9 06/24] virt: sev-guest: Simplify VMPCK and sequence
 number assignments

On 6/19/2024 8:42 PM, Tom Lendacky wrote:
> On 6/19/24 01:06, Nikunj A. Dadhania wrote:
>> On 6/19/2024 2:57 AM, Tom Lendacky wrote:
>>> On 5/30/24 23:30, Nikunj A Dadhania wrote:
> 
>>
>> I have separated patch 6 and 7 for better code review and modular changes.
>>
>> The next patch simplifes this further to:
>>
>> static inline u8 *get_vmpck(struct snp_guest_dev *snp_dev)
>> {
>> 	return snp_dev->secrets->vmpck[snp_dev->vmpck_id];
>> }
>>
>> static bool assign_vmpck(struct snp_guest_dev *dev, unsigned int vmpck_id)
>> {
>> 	if ((vmpck_id + 1) > VMPCK_MAX_NUM)
> 
> Ok, this still has the "+ 1" thing (and it should be >=, right?). How about:

For vmpck_id=3 which is valid, ((3 + 1) >= 4) will exit, which is not correct.

> 
> 	if (!(vmpck_id < VMPCK_MAX_NUM))
> 		return false;
> 

Sure, this is better.

> Just makes it easier to read for me, but if no one else has an issue,
> don't worry about it.

Thanks,
Nikunj