Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Thu, 18 Apr 2024 16:30:23 +0000 | Subject | [PATCH 1/4] KVM: arm64: Trap FFA_VERSION host call in pKVM | From | Sebastian Ene <> |
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The pKVM hypervisor initializes with FF-A version 1.0. Keep the supported version inside the host structure and prevent the host drivers from overwriting the FF-A version with an increased version. Without trapping the call, the host drivers can negotiate a higher version number with TEE which can result in a different memory layout described during the memory sharing calls.
Signed-off-by: Sebastian Ene <sebastianene@google.com> --- arch/arm64/kvm/hyp/nvhe/ffa.c | 43 ++++++++++++++++++++++++++++++++--- 1 file changed, 40 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c index 320f2eaa14a9..023712e8beeb 100644 --- a/arch/arm64/kvm/hyp/nvhe/ffa.c +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c @@ -58,6 +58,7 @@ struct kvm_ffa_buffers { hyp_spinlock_t lock; void *tx; void *rx; + u32 ffa_version; }; /* @@ -640,6 +641,39 @@ static bool do_ffa_features(struct arm_smccc_res *res, return true; } +static void do_ffa_version(struct arm_smccc_res *res, + struct kvm_cpu_context *ctxt) +{ + DECLARE_REG(u32, ffa_req_version, ctxt, 1); + u32 current_version; + + hyp_spin_lock(&host_buffers.lock); + current_version = host_buffers.ffa_version; + if (FFA_MAJOR_VERSION(ffa_req_version) != FFA_MAJOR_VERSION(current_version)) { + res->a0 = FFA_RET_NOT_SUPPORTED; + goto unlock; + } + + /* + * If the client driver tries to downgrade the version, we need to ask + * first if TEE supports it. + */ + if (FFA_MINOR_VERSION(ffa_req_version) < FFA_MINOR_VERSION(current_version)) { + arm_smccc_1_1_smc(FFA_VERSION, ffa_req_version, 0, + 0, 0, 0, 0, 0, + res); + if (res->a0 == FFA_RET_NOT_SUPPORTED) + goto unlock; + + host_buffers.ffa_version = ffa_req_version; + goto unlock; + } + + res->a0 = current_version; +unlock: + hyp_spin_unlock(&host_buffers.lock); +} + bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id) { struct arm_smccc_res res; @@ -686,6 +720,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id) case FFA_MEM_FRAG_TX: do_ffa_mem_frag_tx(&res, host_ctxt); goto out_handled; + case FFA_VERSION: + do_ffa_version(&res, host_ctxt); + goto out_handled; } if (ffa_call_supported(func_id)) @@ -726,6 +763,8 @@ int hyp_ffa_init(void *pages) if (FFA_MAJOR_VERSION(res.a0) != 1) return -EOPNOTSUPP; + host_buffers.ffa_version = res.a0; + arm_smccc_1_1_smc(FFA_ID_GET, 0, 0, 0, 0, 0, 0, 0, &res); if (res.a0 != FFA_SUCCESS) return -EOPNOTSUPP; @@ -772,9 +811,7 @@ int hyp_ffa_init(void *pages) .rx = rx, }; - host_buffers = (struct kvm_ffa_buffers) { - .lock = __HYP_SPIN_LOCK_UNLOCKED, - }; + host_buffers.lock = __HYP_SPIN_LOCK_UNLOCKED; return 0; } -- 2.44.0.769.g3c40516874-goog
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