linux-kernel - Re: [PATCH v7 4/5] KVM: arm64: Bump the supported version of FF-A to 1.2

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Message-ID: <aHpP7fntDQ7SMPAC@willie-the-truck>
Date: Fri, 18 Jul 2025 14:45:17 +0100
From: Will Deacon <will@...nel.org>
To: perlarsen@...gle.com
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
	Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Sudeep Holla <sudeep.holla@....com>,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, ahomescu@...gle.com,
	armellel@...gle.com, arve@...roid.com, ayrton@...gle.com,
	qperret@...gle.com, sebastianene@...gle.com, qwandor@...gle.com
Subject: Re: [PATCH v7 4/5] KVM: arm64: Bump the supported version of FF-A to
 1.2

On Tue, Jul 01, 2025 at 10:06:37PM +0000, Per Larsen via B4 Relay wrote:
> From: Per Larsen <perlarsen@...gle.com>
> 
> FF-A version 1.2 introduces the DIRECT_REQ2 ABI. Bump the FF-A version
> preferred by the hypervisor as a precursor to implementing the 1.2-only
> FFA_MSG_SEND_DIRECT_REQ2 and FFA_MSG_SEND_RESP2 messaging interfaces.
> 
> We must also use SMCCC 1.2 for 64-bit SMCs if hypervisor negotiated FF-A
> 1.2, so ffa_set_retval is updated and a new function to call 64-bit smcs
> using SMCCC 1.2 with fallback to SMCCC 1.1 is introduced.
> 
> Update ffa_call_supported to mark FF-A 1.2 interfaces as unsupported
> lest they get forwarded.
> 
> Co-developed-by: Ayrton Munoz <ayrton@...gle.com>
> Signed-off-by: Ayrton Munoz <ayrton@...gle.com>
> Signed-off-by: Per Larsen <perlarsen@...gle.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/ffa.c | 18 ++++++++++++++----
>  include/linux/arm_ffa.h       |  1 +
>  2 files changed, 15 insertions(+), 4 deletions(-)

This patch needs to be split into smaller chunks as it's doing a number
of things in one go.

> diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> index 5fd6474d96ae4b90d99796ee81bb36373219afc4..79d834120a3f3d26e17e9170c60012b60c6f5a5e 100644
> --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> @@ -678,6 +678,13 @@ static bool ffa_call_supported(u64 func_id)
>  	case FFA_NOTIFICATION_SET:
>  	case FFA_NOTIFICATION_GET:
>  	case FFA_NOTIFICATION_INFO_GET:
> +	/* Optional interfaces added in FF-A 1.2 */
> +	case FFA_MSG_SEND_DIRECT_REQ2:		/* Optional per 7.5.1 */
> +	case FFA_MSG_SEND_DIRECT_RESP2:		/* Optional per 7.5.1 */
> +	case FFA_CONSOLE_LOG:			/* Optional per 13.1: not in Table 13.1 */
> +	case FFA_PARTITION_INFO_GET_REGS:	/* Optional for virtual instances per 13.1 */
> +	/* Unsupported interfaces added in FF-A 1.2 */
> +	case FFA_EL3_INTR_HANDLE:		/* Only valid for secure physical instances */
>  		return false;
>  	}

This could be a standalone change ^^^

>  
> @@ -734,7 +741,10 @@ static int hyp_ffa_post_init(void)
>  	if (res.a0 != FFA_SUCCESS)
>  		return -EOPNOTSUPP;
>  
> -	switch (res.a2) {
> +	if ((res.a2 & GENMASK(15, 2)) != 0 || res.a3 != 0)
> +		return -EINVAL;

Why are you checking bits a2[15:2] and a3? The spec says they MBZ,
so we shouldn't care about enforcing that. In fact, adding the check
probably means we'll fail if those bits get allocated in future.

> +
> +	switch (res.a2 & FFA_FEAT_RXTX_MIN_SZ_MASK) {

That makes sense, and can be its own patch.

>  	case FFA_FEAT_RXTX_MIN_SZ_4K:
>  		min_rxtx_sz = SZ_4K;
>  		break;
> @@ -931,7 +941,7 @@ int hyp_ffa_init(void *pages)
>  
>  	arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) {
>  		.a0 = FFA_VERSION,
> -		.a1 = FFA_VERSION_1_1,
> +		.a1 = FFA_VERSION_1_2,
>
>  	}, &res);
>  	if (res.a0 == FFA_RET_NOT_SUPPORTED)
>  		return 0;
> @@ -952,10 +962,10 @@ int hyp_ffa_init(void *pages)
>  	if (FFA_MAJOR_VERSION(res.a0) != 1)
>  		return -EOPNOTSUPP;
>  
> -	if (FFA_MINOR_VERSION(res.a0) < FFA_MINOR_VERSION(FFA_VERSION_1_1))
> +	if (FFA_MINOR_VERSION(res.a0) < FFA_MINOR_VERSION(FFA_VERSION_1_2))
>  		hyp_ffa_version = res.a0;
>  	else
> -		hyp_ffa_version = FFA_VERSION_1_1;
> +		hyp_ffa_version = FFA_VERSION_1_2;

The move to v1.2 can also be its own patch. So you end up with three in
total.

Will