Re: [PATCH v2] drivers/crypto: Mark QCE as BROKEN

[Eric Biggers <ebiggers@kernel.org>]

On Wed, Jul 22, 2026 at 01:33:51AM -0700, Bartosz Golaszewski wrote:
> > Also, what can the current driver do that cannot be done better using
> > software crypto?  I understand that you have future plans to add more
> > features to the driver, but those are not relevant to this discussion.
> >
> 
> We can offload crypto operations to the QCE saving CPU cycles but more
> importantly, the QCE provides HW based isolation which some vendors care
> about.

Do you have any concrete proof of anyone using this with a specific
Linux kernel feature and actually getting a benefit from it?

Just for some additional context, I've been on the Android team for many
years and have worked with lots of companies shipping Android devices
with Qualcomm SoCs.  I also upstreamed the support for the
Qualcomm Inline Crypto Engine (ICE)
(https://lore.kernel.org/all/20200710072013.177481-6-ebiggers@kernel.org/
https://lore.kernel.org/linux-mmc/20210126001456.382989-9-ebiggers@kernel.org/),
which is what people actually use and isn't the same as QCE.

The only times the Linux QCE driver has ever come up is when someone
used it accidentally and it destroyed their performance (due to the
20-60x slower performance than the CPU) or caused a filesystem hang.

These issues get reported to me -- sometimes even from Qualcomm
themselves!  It's kind of annoying.

(Fortunately it's also quite rare, since the vast majority of people
just ignore QCE and don't make the mistake of using it in Linux.)

As far as I can tell, what actually works and what people actually use
in Linux on Qualcomm SoCs is:

- The Qualcomm Inline Crypto Engine (ICE) for storage encryption

- The ARMv8 Crypto Extensions everywhere else, e.g. dm-verity

> These are future plans, yes. But right now we do have active users of this
> IP

Just because it may be used by the Arm secure world doesn't mean it is
useful in Linux.

- Eric