MIPS: Add & use CP0_EntryHi ASID definitions

Add definitions for the ASID field in CP0_EntryHi (along with the soon
to be used ASIDX field), and use them in a few previously hardcoded
cases.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13205/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mipsregs.h

@@ -229,6 +229,8 @@
 
 /* MIPS32/64 EntryHI bit definitions */
 #define MIPS_ENTRYHI_EHINV	(_ULCAST_(1) << 10)
+#define MIPS_ENTRYHI_ASIDX	(_ULCAST_(0x3) << 8)
+#define MIPS_ENTRYHI_ASID	(_ULCAST_(0xff) << 0)
 
 /*
  * R4x00 interrupt enable / cause bits

arch/mips/kernel/genex.S

@@ -455,7 +455,7 @@ NESTED(nmi_handler, PT_SIZE, sp)
 	.set	noreorder
 	/* check if TLB contains a entry for EPC */
 	MFC0	k1, CP0_ENTRYHI
-	andi	k1, 0xff	/* ASID_MASK */
+	andi	k1, MIPS_ENTRYHI_ASID
 	MFC0	k0, CP0_EPC
 	PTR_SRL k0, _PAGE_SHIFT + 1
 	PTR_SLL k0, _PAGE_SHIFT + 1

arch/mips/kvm/locore.S

@@ -164,7 +164,7 @@ FEXPORT(__kvm_mips_load_asid)
 	INT_SLL	t2, t2, 2                   /* x4 */
 	REG_ADDU t3, t1, t2
 	LONG_L	k0, (t3)
-	andi	k0, k0, 0xff
+	andi	k0, k0, MIPS_ENTRYHI_ASID
 	mtc0	k0, CP0_ENTRYHI
 	ehb
 
@@ -483,7 +483,7 @@ __kvm_mips_return_to_guest:
 	INT_SLL	t2, t2, 2		/* x4 */
 	REG_ADDU t3, t1, t2
 	LONG_L	k0, (t3)
-	andi	k0, k0, 0xff
+	andi	k0, k0, MIPS_ENTRYHI_ASID
 	mtc0	k0, CP0_ENTRYHI
 	ehb
 

arch/mips/pci/pci-alchemy.c

@@ -76,7 +76,7 @@ static void mod_wired_entry(int entry, unsigned long entrylo0,
 	unsigned long old_ctx;
 
 	/* Save old context and create impossible VPN2 value */
-	old_ctx = read_c0_entryhi() & 0xff;
+	old_ctx = read_c0_entryhi() & MIPS_ENTRYHI_ASID;
 	old_pagemask = read_c0_pagemask();
 	write_c0_index(entry);
 	write_c0_pagemask(pagemask);