Re: [PATCH, RFC 26/62] keys/mktme: Move the MKTME payload into a cache aligned structure

[Alison Schofield]

On Fri, Jun 14, 2019 at 01:35:23PM +0200, Peter Zijlstra wrote:
> On Wed, May 08, 2019 at 05:43:46PM +0300, Kirill A. Shutemov wrote:
> 
> > +/* Copy the payload to the HW programming structure and program this KeyID */
> > +static int mktme_program_keyid(int keyid, struct mktme_payload *payload)
> > +{
> > +	struct mktme_key_program *kprog = NULL;
> > +	int ret;
> > +
> > +	kprog = kmem_cache_zalloc(mktme_prog_cache, GFP_ATOMIC);
> 
> Why GFP_ATOMIC, afaict neither of the usage is with a spinlock held.

Got it. GFP_ATOMIC not needed.
That said, this is an artifact of reworking the locking, and that 
locking may need to change again. If it does, will try to pre-allocate
rather than depend on GFP_ATOMIC here.

> 
> > +	if (!kprog)
> > +		return -ENOMEM;
> > +
> > +	/* Hardware programming requires cached aligned struct */
> > +	kprog->keyid = keyid;
> > +	kprog->keyid_ctrl = payload->keyid_ctrl;
> > +	memcpy(kprog->key_field_1, payload->data_key, MKTME_AES_XTS_SIZE);
> > +	memcpy(kprog->key_field_2, payload->tweak_key, MKTME_AES_XTS_SIZE);
> > +
> > +	ret = MKTME_PROG_SUCCESS;	/* Future programming call */
> > +	kmem_cache_free(mktme_prog_cache, kprog);
> > +	return ret;
> > +}