Re: [Part2 PATCH v6.1 16/38] crypto: ccp: Add Secure Encrypted Virtualization (SEV) command support

On 10/30/17 12:57 PM, Borislav Petkov wrote:

On Mon, Oct 30, 2017 at 12:49:14PM -0500, Brijesh Singh wrote:

quoted

If the buffer is allocated on the stack then there is no guarantee that

static global is not allocated on the stack.

Okay, Just tried static global with CONFIG_VMAP_STACK=y and I am getting
wrong physical address with __pa. PSP command fails with error code
"INVALID_ADDRESS". The same thing works fine with kmalloc() buffer.

quoted

I can certainly move the allocation outside, but then it may increase the
code size in other functions. If its not a big deal then I would prefer to
keep what we have.

Avoiding repeated k*alloc calls is always a good thing. Actually kmalloc-ing 20
bytes each time sounds like it is not worth the calling overhead to me.

To avoid repeated k*alloc calls, I could devm_kzalloc() these variable 
during sev_init() and reuse them when needed.