diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 23c326a06b2d40cde5dbdc1cf491a1441766a82e..a14927360be267d676cb000f3147bc7bf3f1a052 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -444,6 +444,18 @@ SYM_FUNC_START(__cpu_setup)
 	mov	x10, #(SYS_GCR_EL1_RRND | SYS_GCR_EL1_EXCL_MASK)
 	msr_s	SYS_GCR_EL1, x10
 
+	/*
+	 * If GCR_EL1.RRND=1 is implemented the same way as RRND=0, then
+	 * RGSR_EL1.SEED must be non-zero for IRG to produce
+	 * pseudorandom numbers. As RGSR_EL1 is UNKNOWN out of reset, we
+	 * must initialize it.
+	 */
+	mrs	x10, CNTVCT_EL0
+	ands	x10, x10, #SYS_RGSR_EL1_SEED_MASK
+	csinc	x10, x10, xzr, ne
+	lsl	x10, x10, #SYS_RGSR_EL1_SEED_SHIFT
+	msr_s	SYS_RGSR_EL1, x10
+
 	/* clear any pending tag check faults in TFSR*_EL1 */
 	msr_s	SYS_TFSR_EL1, xzr
 	msr_s	SYS_TFSRE0_EL1, xzr