MIPS: Add probing & defs for VZ & guest features

Add a few new cpu-features.h definitions for VZ sub-features, namely the
existence of the CP0_GuestCtl0Ext, CP0_GuestCtl1, and CP0_GuestCtl2
registers, and support for GuestID to dialias TLB entries belonging to
different guests.

Also add certain features present in the guest, with the naming scheme
cpu_guest_has_*. These are added separately to the main options bitfield
since they generally parallel similar features in the root context. A
few of these (FPU, MSA, watchpoints, perf counters, CP0_[X]ContextConfig
registers, MAAR registers, and probably others in future) can be
dynamically configured in the guest context, for which the
cpu_guest_has_dyn_* macros are added.

[ralf@linux-mips.org: Resolve merge conflict.]

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13231/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 232 insertions, 0 deletions

diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 31c27576a931..5ac5c3e23460 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -915,6 +915,235 @@ static void decode_configs(struct cpuinfo_mips *c)
 #endif
 }
 
+/*
+ * Probe for certain guest capabilities by writing config bits and reading back.
+ * Finally write back the original value.
+ */
+#define probe_gc0_config(name, maxconf, bits)				\
+do {									\
+	unsigned int tmp;						\
+	tmp = read_gc0_##name();					\
+	write_gc0_##name(tmp | (bits));					\
+	back_to_back_c0_hazard();					\
+	maxconf = read_gc0_##name();					\
+	write_gc0_##name(tmp);						\
+} while (0)
+
+/*
+ * Probe for dynamic guest capabilities by changing certain config bits and
+ * reading back to see if they change. Finally write back the original value.
+ */
+#define probe_gc0_config_dyn(name, maxconf, dynconf, bits)		\
+do {									\
+	maxconf = read_gc0_##name();					\
+	write_gc0_##name(maxconf ^ (bits));				\
+	back_to_back_c0_hazard();					\
+	dynconf = maxconf ^ read_gc0_##name();				\
+	write_gc0_##name(maxconf);					\
+	maxconf |= dynconf;						\
+} while (0)
+
+static inline unsigned int decode_guest_config0(struct cpuinfo_mips *c)
+{
+	unsigned int config0;
+
+	probe_gc0_config(config, config0, MIPS_CONF_M);
+
+	if (config0 & MIPS_CONF_M)
+		c->guest.conf |= BIT(1);
+	return config0 & MIPS_CONF_M;
+}
+
+static inline unsigned int decode_guest_config1(struct cpuinfo_mips *c)
+{
+	unsigned int config1, config1_dyn;
+
+	probe_gc0_config_dyn(config1, config1, config1_dyn,
+			     MIPS_CONF_M | MIPS_CONF1_PC | MIPS_CONF1_WR |
+			     MIPS_CONF1_FP);
+
+	if (config1 & MIPS_CONF1_FP)
+		c->guest.options |= MIPS_CPU_FPU;
+	if (config1_dyn & MIPS_CONF1_FP)
+		c->guest.options_dyn |= MIPS_CPU_FPU;
+
+	if (config1 & MIPS_CONF1_WR)
+		c->guest.options |= MIPS_CPU_WATCH;
+	if (config1_dyn & MIPS_CONF1_WR)
+		c->guest.options_dyn |= MIPS_CPU_WATCH;
+
+	if (config1 & MIPS_CONF1_PC)
+		c->guest.options |= MIPS_CPU_PERF;
+	if (config1_dyn & MIPS_CONF1_PC)
+		c->guest.options_dyn |= MIPS_CPU_PERF;
+
+	if (config1 & MIPS_CONF_M)
+		c->guest.conf |= BIT(2);
+	return config1 & MIPS_CONF_M;
+}
+
+static inline unsigned int decode_guest_config2(struct cpuinfo_mips *c)
+{
+	unsigned int config2;
+
+	probe_gc0_config(config2, config2, MIPS_CONF_M);
+
+	if (config2 & MIPS_CONF_M)
+		c->guest.conf |= BIT(3);
+	return config2 & MIPS_CONF_M;
+}
+
+static inline unsigned int decode_guest_config3(struct cpuinfo_mips *c)
+{
+	unsigned int config3, config3_dyn;
+
+	probe_gc0_config_dyn(config3, config3, config3_dyn,
+			     MIPS_CONF_M | MIPS_CONF3_MSA | MIPS_CONF3_CTXTC);
+
+	if (config3 & MIPS_CONF3_CTXTC)
+		c->guest.options |= MIPS_CPU_CTXTC;
+	if (config3_dyn & MIPS_CONF3_CTXTC)
+		c->guest.options_dyn |= MIPS_CPU_CTXTC;
+
+	if (config3 & MIPS_CONF3_PW)
+		c->guest.options |= MIPS_CPU_HTW;
+
+	if (config3 & MIPS_CONF3_SC)
+		c->guest.options |= MIPS_CPU_SEGMENTS;
+
+	if (config3 & MIPS_CONF3_BI)
+		c->guest.options |= MIPS_CPU_BADINSTR;
+	if (config3 & MIPS_CONF3_BP)
+		c->guest.options |= MIPS_CPU_BADINSTRP;
+
+	if (config3 & MIPS_CONF3_MSA)
+		c->guest.ases |= MIPS_ASE_MSA;
+	if (config3_dyn & MIPS_CONF3_MSA)
+		c->guest.ases_dyn |= MIPS_ASE_MSA;
+
+	if (config3 & MIPS_CONF_M)
+		c->guest.conf |= BIT(4);
+	return config3 & MIPS_CONF_M;
+}
+
+static inline unsigned int decode_guest_config4(struct cpuinfo_mips *c)
+{
+	unsigned int config4;
+
+	probe_gc0_config(config4, config4,
+			 MIPS_CONF_M | MIPS_CONF4_KSCREXIST);
+
+	c->guest.kscratch_mask = (config4 & MIPS_CONF4_KSCREXIST)
+				>> MIPS_CONF4_KSCREXIST_SHIFT;
+
+	if (config4 & MIPS_CONF_M)
+		c->guest.conf |= BIT(5);
+	return config4 & MIPS_CONF_M;
+}
+
+static inline unsigned int decode_guest_config5(struct cpuinfo_mips *c)
+{
+	unsigned int config5, config5_dyn;
+
+	probe_gc0_config_dyn(config5, config5, config5_dyn,
+			 MIPS_CONF_M | MIPS_CONF5_MRP);
+
+	if (config5 & MIPS_CONF5_MRP)
+		c->guest.options |= MIPS_CPU_MAAR;
+	if (config5_dyn & MIPS_CONF5_MRP)
+		c->guest.options_dyn |= MIPS_CPU_MAAR;
+
+	if (config5 & MIPS_CONF5_LLB)
+		c->guest.options |= MIPS_CPU_RW_LLB;
+
+	if (config5 & MIPS_CONF_M)
+		c->guest.conf |= BIT(6);
+	return config5 & MIPS_CONF_M;
+}
+
+static inline void decode_guest_configs(struct cpuinfo_mips *c)
+{
+	unsigned int ok;
+
+	ok = decode_guest_config0(c);
+	if (ok)
+		ok = decode_guest_config1(c);
+	if (ok)
+		ok = decode_guest_config2(c);
+	if (ok)
+		ok = decode_guest_config3(c);
+	if (ok)
+		ok = decode_guest_config4(c);
+	if (ok)
+		decode_guest_config5(c);
+}
+
+static inline void cpu_probe_guestctl0(struct cpuinfo_mips *c)
+{
+	unsigned int guestctl0, temp;
+
+	guestctl0 = read_c0_guestctl0();
+
+	if (guestctl0 & MIPS_GCTL0_G0E)
+		c->options |= MIPS_CPU_GUESTCTL0EXT;
+	if (guestctl0 & MIPS_GCTL0_G1)
+		c->options |= MIPS_CPU_GUESTCTL1;
+	if (guestctl0 & MIPS_GCTL0_G2)
+		c->options |= MIPS_CPU_GUESTCTL2;
+	if (!(guestctl0 & MIPS_GCTL0_RAD)) {
+		c->options |= MIPS_CPU_GUESTID;
+
+		/*
+		 * Probe for Direct Root to Guest (DRG). Set GuestCtl1.RID = 0
+		 * first, otherwise all data accesses will be fully virtualised
+		 * as if they were performed by guest mode.
+		 */
+		write_c0_guestctl1(0);
+		tlbw_use_hazard();
+
+		write_c0_guestctl0(guestctl0 | MIPS_GCTL0_DRG);
+		back_to_back_c0_hazard();
+		temp = read_c0_guestctl0();
+
+		if (temp & MIPS_GCTL0_DRG) {
+			write_c0_guestctl0(guestctl0);
+			c->options |= MIPS_CPU_DRG;
+		}
+	}
+}
+
+static inline void cpu_probe_guestctl1(struct cpuinfo_mips *c)
+{
+	if (cpu_has_guestid) {
+		/* determine the number of bits of GuestID available */
+		write_c0_guestctl1(MIPS_GCTL1_ID);
+		back_to_back_c0_hazard();
+		c->guestid_mask = (read_c0_guestctl1() & MIPS_GCTL1_ID)
+						>> MIPS_GCTL1_ID_SHIFT;
+		write_c0_guestctl1(0);
+	}
+}
+
+static inline void cpu_probe_gtoffset(struct cpuinfo_mips *c)
+{
+	/* determine the number of bits of GTOffset available */
+	write_c0_gtoffset(0xffffffff);
+	back_to_back_c0_hazard();
+	c->gtoffset_mask = read_c0_gtoffset();
+	write_c0_gtoffset(0);
+}
+
+static inline void cpu_probe_vz(struct cpuinfo_mips *c)
+{
+	cpu_probe_guestctl0(c);
+	if (cpu_has_guestctl1)
+		cpu_probe_guestctl1(c);
+
+	cpu_probe_gtoffset(c);
+
+	decode_guest_configs(c);
+}
+
 #define R4K_OPTS (MIPS_CPU_TLB | MIPS_CPU_4KEX | MIPS_CPU_4K_CACHE \
 		| MIPS_CPU_COUNTER)
 
@@ -1817,6 +2046,9 @@ void cpu_probe(void)
 		elf_hwcap |= HWCAP_MIPS_MSA;
 	}
 
+	if (cpu_has_vz)
+		cpu_probe_vz(c);
+
 	cpu_probe_vmbits(c);
 
 #ifdef CONFIG_64BIT