[PATCH 4/4] firmware: arm_ffa: Defer probe until pKVM is initialized

[Yeoreum Yun]

Look good to me.

Reviewed-by: Yeoreum Yun <yeoreum.yun at arm.com>

> When protected KVM is enabled, the kernel includes a pKVM FF-A proxy
> that sits in front of the normal FF-A driver. The proxy has to perform
> its own FF-A version negotiation and setup first, so that it can mediate
> subsequent FF-A traffic correctly.
> 
> Defer FF-A core probing until pKVM has completed initialization. This
> keeps the normal driver from negotiating the FF-A version or performing
> other transport setup before the pKVM proxy is ready, and lets the
> driver model retry probing once the protected KVM state required by the
> FF-A transport is available.
> 
> Suggested-by: Yeoreum Yun <yeoreum.yun at arm.com>
> Signed-off-by: Sudeep Holla <sudeep.holla at kernel.org>
> ---
>  drivers/firmware/arm_ffa/driver.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
> index e9d7dc71c06d..1fba064c2aba 100644
> --- a/drivers/firmware/arm_ffa/driver.c
> +++ b/drivers/firmware/arm_ffa/driver.c
> @@ -43,6 +43,8 @@
>  #include <linux/uuid.h>
>  #include <linux/xarray.h>
>  
> +#include <asm/virt.h>
> +
>  #include "common.h"
>  
>  #define FFA_DRIVER_VERSION	FFA_VERSION_1_2
> @@ -2039,6 +2041,10 @@ static int ffa_probe(struct platform_device *pdev)
>  	u32 buf_sz;
>  	size_t rxtx_bufsz = SZ_4K;
>  
> +	if (IS_BUILTIN(CONFIG_ARM_FFA_TRANSPORT) &&
> +	    is_protected_kvm_enabled() && !is_pkvm_initialized())
> +		return -EPROBE_DEFER;
> +
>  	ret = ffa_transport_init(&invoke_ffa_fn);
>  	if (ret)
>  		return ret;
> 
> -- 
> 2.43.0
> 

-- 
Sincerely,
Yeoreum Yun