On Sat, 2020-10-24 at 09:26 +0100, David Woodhouse wrote:
> 
> And now I wish it was just a simple shift instead of an unholy maze of
> overlapping unions of bitfields. But I'll make more coffee and stare at
> it harder...

Hah, it really *was* unions of the bitfields. This boots...

diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index c65e89bedc93..3e14adba34ba 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -65,6 +65,8 @@ union IO_APIC_reg_03 {
 };
 
 struct IO_APIC_route_entry {
+  union {
+    struct {
 	u64	vector			:  8,
 		delivery_mode		:  3,
 		dest_mode_logical	:  1,
@@ -77,7 +79,8 @@ struct IO_APIC_route_entry {
 		reserved_1		: 17,
 		virt_destid_8_14	:  7,
 		destid_0_7		:  8;
-
+    };
+    struct {
 	u64	ir_shared_0		:  8,
 		ir_zero			:  3,
 		ir_index_15		:  1,
@@ -85,6 +88,8 @@ struct IO_APIC_route_entry {
 		ir_reserved_0		: 31,
 		ir_format		:  1,
 		ir_index_0_14		: 15;
+    };
+  };
 } __attribute__ ((packed));
 
 struct irq_alloc_info;
diff --git a/arch/x86/include/asm/msi.h b/arch/x86/include/asm/msi.h
index 8cf82d134b78..ef9dfaa4603f 100644
--- a/arch/x86/include/asm/msi.h
+++ b/arch/x86/include/asm/msi.h
@@ -25,6 +25,7 @@ typedef struct x86_msi_data {
 
 typedef struct x86_msi_addr_lo {
 	union {
+		struct {
 		u32	reserved_0		:  2,
 			dest_mode_logical	:  1,
 			redirect_hint		:  1,
@@ -32,13 +33,15 @@ typedef struct x86_msi_addr_lo {
 			virt_destid_8_14	:  7,
 			destid_0_7		:  8,
 			base_address		: 12;
-
+		};
+		struct {
 		u32	dmar_reserved_0		:  2,
 			dmar_index_15		:  1,
 			dmar_subhandle_valid	:  1,
 			dmar_format		:  1,
 			dmar_index_0_14		: 15,
 			dmar_base_address	: 12;
+		};
 	};
 } __attribute__ ((packed)) arch_msi_msg_addr_lo_t;
 #define arch_msi_msg_addr_lo	x86_msi_addr_lo