KVM: arm64: Add support for FFA_PARTITION_INFO_GET

Handle the FFA_PARTITION_INFO_GET host call inside the pKVM hypervisor
and copy the response message back to the host buffers.
Signed-off-by: Sebastian Ene <sebastianene@google.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240613132035.1070360-3-sebastianene@google.comSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

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

@@ -719,6 +719,55 @@ static void do_ffa_version(struct arm_smccc_res *res,
 	hyp_spin_unlock(&version_lock);
 }
 
+static void do_ffa_part_get(struct arm_smccc_res *res,
+			    struct kvm_cpu_context *ctxt)
+{
+	DECLARE_REG(u32, uuid0, ctxt, 1);
+	DECLARE_REG(u32, uuid1, ctxt, 2);
+	DECLARE_REG(u32, uuid2, ctxt, 3);
+	DECLARE_REG(u32, uuid3, ctxt, 4);
+	DECLARE_REG(u32, flags, ctxt, 5);
+	u32 count, partition_sz, copy_sz;
+
+	hyp_spin_lock(&host_buffers.lock);
+	if (!host_buffers.rx) {
+		ffa_to_smccc_res(res, FFA_RET_BUSY);
+		goto out_unlock;
+	}
+
+	arm_smccc_1_1_smc(FFA_PARTITION_INFO_GET, uuid0, uuid1,
+			  uuid2, uuid3, flags, 0, 0,
+			  res);
+
+	if (res->a0 != FFA_SUCCESS)
+		goto out_unlock;
+
+	count = res->a2;
+	if (!count)
+		goto out_unlock;
+
+	if (hyp_ffa_version > FFA_VERSION_1_0) {
+		/* Get the number of partitions deployed in the system */
+		if (flags & 0x1)
+			goto out_unlock;
+
+		partition_sz  = res->a3;
+	} else {
+		/* FFA_VERSION_1_0 lacks the size in the response */
+		partition_sz = FFA_1_0_PARTITON_INFO_SZ;
+	}
+
+	copy_sz = partition_sz * count;
+	if (copy_sz > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) {
+		ffa_to_smccc_res(res, FFA_RET_ABORTED);
+		goto out_unlock;
+	}
+
+	memcpy(host_buffers.rx, hyp_buffers.rx, copy_sz);
+out_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;
@@ -773,6 +822,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
 	case FFA_VERSION:
 		do_ffa_version(&res, host_ctxt);
 		goto out_handled;
+	case FFA_PARTITION_INFO_GET:
+		do_ffa_part_get(&res, host_ctxt);
+		goto out_handled;
 	}
 
 	if (ffa_call_supported(func_id))

include/linux/arm_ffa.h

@@ -212,6 +212,9 @@ bool ffa_device_is_valid(struct ffa_device *ffa_dev) { return false; }
 
 extern const struct bus_type ffa_bus_type;
 
+/* The FF-A 1.0 partition structure lacks the uuid[4] */
+#define FFA_1_0_PARTITON_INFO_SZ	(8)
+
 /* FFA transport related */
 struct ffa_partition_info {
 	u16 id;