MIPS: Support extended ASIDs

Add support for extended ASIDs as determined by the Config4.AE bit.
Since the only supported CPUs known to implement this are Netlogic XLP
and MIPS I6400, select this variable ASID support based upon
CONFIG_CPU_XLP and CONFIG_CPU_MIPSR6.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Jayachandran C. <jchandra@broadcom.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13211/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1706,6 +1706,7 @@ config CPU_XLP
 	select CPU_HAS_PREFETCH
 	select CPU_MIPSR2
 	select CPU_SUPPORTS_HUGEPAGES
+	select MIPS_ASID_BITS_VARIABLE
 	help
 	  Netlogic Microsystems XLP processors.
 endchoice
@@ -2001,6 +2002,7 @@ config CPU_MIPSR6
 	bool
 	default y if CPU_MIPS32_R6 || CPU_MIPS64_R6
 	select HAVE_ARCH_BITREVERSE
+	select MIPS_ASID_BITS_VARIABLE
 	select MIPS_SPRAM
 
 config EVA
@@ -2457,9 +2459,13 @@ config MIPS_ASID_SHIFT
 
 config MIPS_ASID_BITS
 	int
+	default 0 if MIPS_ASID_BITS_VARIABLE
 	default 6 if CPU_R3000 || CPU_TX39XX
 	default 8
 
+config MIPS_ASID_BITS_VARIABLE
+	bool
+
 #
 # - Highmem only makes sense for the 32-bit kernel.
 # - The current highmem code will only work properly on physically indexed

arch/mips/include/asm/cpu-info.h

@@ -40,6 +40,9 @@ struct cache_desc {
 
 struct cpuinfo_mips {
 	unsigned long		asid_cache;
+#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE
+	unsigned long		asid_mask;
+#endif
 
 	/*
 	 * Capability and feature descriptor structure for MIPS CPU
@@ -139,7 +142,18 @@ static inline unsigned long cpu_asid_inc(void)
 
 static inline unsigned long cpu_asid_mask(struct cpuinfo_mips *cpuinfo)
 {
+#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE
+	return cpuinfo->asid_mask;
+#endif
 	return ((1 << CONFIG_MIPS_ASID_BITS) - 1) << CONFIG_MIPS_ASID_SHIFT;
 }
 
+static inline void set_cpu_asid_mask(struct cpuinfo_mips *cpuinfo,
+				     unsigned long asid_mask)
+{
+#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE
+	cpuinfo->asid_mask = asid_mask;
+#endif
+}
+
 #endif /* __ASM_CPU_INFO_H */

arch/mips/kernel/asm-offsets.c

@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/kbuild.h>
 #include <linux/suspend.h>
+#include <asm/cpu-info.h>
 #include <asm/pm.h>
 #include <asm/ptrace.h>
 #include <asm/processor.h>
@@ -338,6 +339,15 @@ void output_pm_defines(void)
 }
 #endif
 
+void output_cpuinfo_defines(void)
+{
+	COMMENT(" MIPS cpuinfo offsets. ");
+	DEFINE(CPUINFO_SIZE, sizeof(struct cpuinfo_mips));
+#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE
+	OFFSET(CPUINFO_ASID_MASK, cpuinfo_mips, asid_mask);
+#endif
+}
+
 void output_kvm_defines(void)
 {
 	COMMENT(" KVM/MIPS Specfic offsets. ");

arch/mips/kernel/cpu-probe.c

@@ -732,6 +732,7 @@ static inline unsigned int decode_config4(struct cpuinfo_mips *c)
 	unsigned int newcf4;
 	unsigned int mmuextdef;
 	unsigned int ftlb_page = MIPS_CONF4_FTLBPAGESIZE;
+	unsigned long asid_mask;
 
 	config4 = read_c0_config4();
 
@@ -792,6 +793,18 @@ static inline unsigned int decode_config4(struct cpuinfo_mips *c)
 
 	c->kscratch_mask = (config4 >> 16) & 0xff;
 
+	asid_mask = MIPS_ENTRYHI_ASID;
+	if (config4 & MIPS_CONF4_AE)
+		asid_mask |= MIPS_ENTRYHI_ASIDX;
+	set_cpu_asid_mask(c, asid_mask);
+
+	/*
+	 * Warn if the computed ASID mask doesn't match the mask the kernel
+	 * is built for. This may indicate either a serious problem or an
+	 * easy optimisation opportunity, but either way should be addressed.
+	 */
+	WARN_ON(asid_mask != cpu_asid_mask(c));
+
 	return config4 & MIPS_CONF_M;
 }
 

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, MIPS_ENTRYHI_ASID
+	andi	k1, MIPS_ENTRYHI_ASID | MIPS_ENTRYHI_ASIDX
 	MFC0	k0, CP0_EPC
 	PTR_SRL k0, _PAGE_SHIFT + 1
 	PTR_SLL k0, _PAGE_SHIFT + 1

arch/mips/kvm/locore.S

@@ -137,7 +137,14 @@ FEXPORT(__kvm_mips_load_asid)
 	INT_SLL	t2, t2, 2                   /* x4 */
 	REG_ADDU t3, t1, t2
 	LONG_L	k0, (t3)
+#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE
+	li	t3, CPUINFO_SIZE/4
+	mul	t2, t2, t3		/* x sizeof(struct cpuinfo_mips)/4 */
+	LONG_L	t2, (cpu_data + CPUINFO_ASID_MASK)(t2)
+	and	k0, k0, t2
+#else
 	andi	k0, k0, MIPS_ENTRYHI_ASID
+#endif
 	mtc0	k0, CP0_ENTRYHI
 	ehb
 
@@ -449,7 +456,14 @@ __kvm_mips_return_to_guest:
 	INT_SLL	t2, t2, 2		/* x4 */
 	REG_ADDU t3, t1, t2
 	LONG_L	k0, (t3)
+#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE
+	li	t3, CPUINFO_SIZE/4
+	mul	t2, t2, t3		/* x sizeof(struct cpuinfo_mips)/4 */
+	LONG_L	t2, (cpu_data + CPUINFO_ASID_MASK)(t2)
+	and	k0, k0, t2
+#else
 	andi	k0, k0, MIPS_ENTRYHI_ASID
+#endif
 	mtc0	k0, CP0_ENTRYHI
 	ehb