diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 61177bac49fa7fe7831c381598708a3946a868fe..338840c00e8ed72f339aa8fd513c2b2729ce14d7 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -63,6 +63,23 @@ struct arm64_ftr_bits {
 	s64		safe_val; /* safe value for FTR_EXACT features */
 };
 
+/*
+ * Describe the early feature override to the core override code:
+ *
+ * @val			Values that are to be merged into the final
+ *			sanitised value of the register. Only the bitfields
+ *			set to 1 in @mask are valid
+ * @mask		Mask of the features that are overridden by @val
+ *
+ * A @mask field set to full-1 indicates that the corresponding field
+ * in @val is a valid override.
+ *
+ * A @mask field set to full-0 with the corresponding @val field set
+ * to full-0 denotes that this field has no override
+ *
+ * A @mask field set to full-0 with the corresponding @val field set
+ * to full-1 denotes thath this field has an invalid override.
+ */
 struct arm64_ftr_override {
 	u64		val;
 	u64		mask;
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 066030717a4c7f4c555659eeeb362871f25b7583..6de15deaa9126f7a5e5a030058e8b1ff5565ee87 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -809,6 +809,12 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new)
 					reg->name,
 					ftrp->shift + ftrp->width - 1,
 					ftrp->shift, str, tmp);
+		} else if ((ftr_mask & reg->override->val) == ftr_mask) {
+			reg->override->val &= ~ftr_mask;
+			pr_warn("%s[%d:%d]: impossible override, ignored\n",
+				reg->name,
+				ftrp->shift + ftrp->width - 1,
+				ftrp->shift);
 		}
 
 		val = arm64_ftr_set_value(ftrp, val, ftr_new);
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 83f1c4b92095e9a6acf0c2eac454f965228bf040..be92fcd319a1b997d91af32de9a80f45a39c2da9 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -25,6 +25,7 @@ struct ftr_set_desc {
 	struct {
 		char			name[FTR_DESC_FIELD_LEN];
 		u8			shift;
+		bool			(*filter)(u64 val);
 	} 				fields[];
 };
 
@@ -124,6 +125,18 @@ static void __init match_options(const char *cmdline)
 			if (find_field(cmdline, regs[i], f, &v))
 				continue;
 
+			/*
+			 * If an override gets filtered out, advertise
+			 * it by setting the value to 0xf, but
+			 * clearing the mask... Yes, this is fragile.
+			 */
+			if (regs[i]->fields[f].filter &&
+			    !regs[i]->fields[f].filter(v)) {
+				regs[i]->override->val  |= mask;
+				regs[i]->override->mask &= ~mask;
+				continue;
+			}
+
 			regs[i]->override->val  &= ~mask;
 			regs[i]->override->val  |= (v << shift) & mask;
 			regs[i]->override->mask |= mask;