From 84f68679032147dcdac9bb4d8eb8f4638e995dc6 Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Tue, 18 Jul 2023 18:45:37 +0000 Subject: [PATCH] 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: Marc Zyngier Acked-by: Will Deacon Link: https://lore.kernel.org/r/20230718184537.3220867-1-oliver.upton@linux.dev Signed-off-by: Oliver Upton --- arch/arm64/kvm/hyp/nvhe/ffa.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c index 58dcd92..ab4f5d1 100644 --- a/arch/arm64/kvm/hyp/nvhe/ffa.c +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c @@ -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); -- 2.7.4