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From:   Martin Fernandez <martin.fernandez@eclypsium.com>
Date:   Tue, 8 Feb 2022 11:39:50 -0300
Message-ID: <CAKgze5aZTocPbn8SDYWJ+wLK7zJFP95=vHU-U+BBF1bc1gPOsg@mail.gmail.com>
Subject: Re: [PATCH v6 1/6] mm/memblock: Tag memblocks with crypto capabilities
To:     Kees Cook <keescook@chromium.org>
Cc:     linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org,
        platform-driver-x86@vger.kernel.org, linux-mm@kvack.org,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
        ardb@kernel.org, dvhart@infradead.org, andy@infradead.org,
        gregkh@linuxfoundation.org, rafael@kernel.org, rppt@kernel.org,
        akpm@linux-foundation.org, daniel.gutson@eclypsium.com,
        hughsient@gmail.com, alex.bazhaniuk@eclypsium.com,
        alison.schofield@intel.com
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On 2/7/22, Kees Cook <keescook@chromium.org> wrote:
> On Thu, Feb 03, 2022 at 01:43:23PM -0300, Martin Fernandez wrote:
>> +/**
>> + * memblock_node_is_crypto_capable - get if whole node is capable
>> + * of encryption
>> + * @nid: number of node
>> + *
>> + * Iterate over all memory memblock_type and find if all regions under
>> + * node @nid are capable of hardware encryption.
>> + *
>> + * Return:
>> + * true if every region in memory memblock_type is capable of
>> + * encryption, false otherwise.
>> + */
>> +bool __init_memblock memblock_node_is_crypto_capable(int nid)
>> +{
>> +	struct memblock_region *region;
>> +	bool crypto_capable = false;
>> +	bool not_crypto_capable = false;
>> +
>> +	for_each_mem_region(region) {
>> +		if (memblock_get_region_node(region) == nid) {
>> +			crypto_capable =
>> +				crypto_capable ||
>> +				(region->flags & MEMBLOCK_CRYPTO_CAPABLE);
>
> This was already mentioned, but I just thought I'd add: this made me
> double-take, given the "||" (instead of "|") in an assignment. It looked
> like a typo, but yes it's correct. I was expecting something like:
>
> 			crypto_capable |=
> 				!!(region->flags & MEMBLOCK_CRYPTO_CAPABLE);
>
>> +			not_crypto_capable =
>> +				not_crypto_capable ||
>> +				!(region->flags & MEMBLOCK_CRYPTO_CAPABLE);
>
> 			not_crypto_capable |=
> 				!(region->flags & MEMBLOCK_CRYPTO_CAPABLE);
>

Yes, this also works. Thanks.