Re: [PATCH v2 3/4] KVM: arm64: Map the hypervisor FF-A buffers on ffa init

[Will Deacon <will@kernel.org>]

On Thu, Feb 27, 2025 at 06:17:48PM +0000, Sebastian Ene wrote:
> Map the hypervisor's buffers irrespective to the host and return
> a linux error code from the FF-A error code on failure. Remove
> the unmap ff-a buffers calls from the hypervisor as it will
> never be called.
> Prevent the host from using FF-A directly with Trustzone
> if the hypervisor could not map its own buffers.
> 
> Signed-off-by: Sebastian Ene <sebastianene@google.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/ffa.c | 46 +++++++++++++----------------------
>  1 file changed, 17 insertions(+), 29 deletions(-)

[...]

> @@ -861,6 +842,7 @@ int hyp_ffa_init(void *pages)
>  {
>  	struct arm_smccc_res res;
>  	void *tx, *rx;
> +	int ret;
>  
>  	if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2)
>  		return 0;
> @@ -911,5 +893,11 @@ int hyp_ffa_init(void *pages)
>  		.lock	= __HYP_SPIN_LOCK_UNLOCKED,
>  	};
>  
> +	/* Map our hypervisor buffers into the SPMD */
> +	ret = ffa_map_hyp_buffers();
> +	if (ret)
> +		return ret;

Doesn't calling RXTX_MAP here undo the fix from c9c012625e12 ("KVM:
arm64: Trap FFA_VERSION host call in pKVM") where we want to allow for
the host to negotiate the version lazily?

Will