[PATCH] arm64: kvm, smccc: Fix vendor uuid

[Sudeep Holla]

(I can't see this original patch in my mailbox, got only Marc's response)

On Mon, Jul 21, 2025 at 02:05:58PM +0100, Jack Thomson wrote:
> From: Jack Thomson <jackabt at amazon.com>
> 
> Commit 13423063c7cb ("arm64: kvm, smccc: Introduce and use API for
> getting hypervisor UUID") replaced the explicit register constants
> with the UUID_INIT macro. However, there is an endian issue, meaning
> the UUID generated and used in the handshake didn't match UUID prior to
> the commit.
> 
> The change in UUID causes the SMCCC vendor handshake to fail with older
> guest kernels, meaning devices such as PTP were not available in the
> guest.
> 
> This patch updates the parameters to the macro to generate a UUID which
> matches the previous value, and re-establish backwards compatibility
> with older guest kernels.
> 

Nice catch. This is result of classic confusion with UUID and GUID especially
coming from Microsoft who tend to use GUID more.

Reviewed-by: Sudeep Holla <sudeep.holla at arm.com>

This also makes me wonder if the initialisation in arch/arm64/hyperv/mshyperv.c
is also wrong or may be that's correct only MS guys can confirm as I couldn't
find the UUID string for that.

-- 
Regards,
Sudeep