Commit 84f68679 authored by Oliver Upton's avatar Oliver Upton
Browse files

KVM: arm64: Allow pKVM on v1.0 compatible FF-A implementations 



pKVM initialization fails on systems with v1.1+ FF-A implementations, as
the hyp does a strict match on the returned version from FFA_VERSION.
This is a stronger assertion than required by the specification, which
requires minor revisions be backwards compatible with earlier revisions
of the same major version.

Relax the check in hyp_ffa_init() to only test the returned major
version. Even though v1.1 broke ABI, the expectation is that firmware
incapable of using the v1.0 ABI return NOT_SUPPORTED instead of a valid
version.

Acked-by: default avatarMarc Zyngier <maz@kernel.org>
Acked-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230718184537.3220867-1-oliver.upton@linux.dev


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 9d2a55b4

arch/arm64/kvm/hyp/nvhe/ffa.c

+14 −1
Original line number Diff line number Diff line
@@ -705,7 +705,20 @@ int hyp_ffa_init(void *pages) 
	if (res.a0 == FFA_RET_NOT_SUPPORTED)

		return 0;



	if (res.a0 != FFA_VERSION_1_0)

	/*

	 * Firmware returns the maximum supported version of the FF-A

	 * implementation. Check that the returned version is

	 * backwards-compatible with the hyp according to the rules in DEN0077A

	 * v1.1 REL0 13.2.1.

	 *

	 * Of course, things are never simple when dealing with firmware. v1.1

	 * broke ABI with v1.0 on several structures, which is itself

	 * incompatible with the aforementioned versioning scheme. The

	 * expectation is that v1.x implementations that do not support the v1.0

	 * ABI return NOT_SUPPORTED rather than a version number, according to

	 * DEN0077A v1.1 REL0 18.6.4.

	 */

	if (FFA_MAJOR_VERSION(res.a0) != 1)

		return -EOPNOTSUPP;



	arm_smccc_1_1_smc(FFA_ID_GET, 0, 0, 0, 0, 0, 0, 0, &res);