[PATCH 02/19] riscv: cpufeature: Fix thead vector hwcap removal

[Charlie Jenkins]

The riscv_cpuinfo struct that contains mvendorid and marchid is not
populated until all harts are booted which happens after the DT parsing.
Use the vendorid/archid values from the DT if available or assume all
harts have the same values as the boot hart as a fallback.

Fixes: d82f32202e0d ("RISC-V: Ignore V from the riscv,isa DT property on older T-Head CPUs")
Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
---
 arch/riscv/include/asm/sbi.h   |  2 ++
 arch/riscv/kernel/cpu.c        | 20 ++++++++++++++++++++
 arch/riscv/kernel/cpufeature.c | 22 ++++++++++++++++++++--
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 6e68f8dff76b..0fab508a65b3 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -370,6 +370,8 @@ static inline int sbi_remote_fence_i(const struct cpumask *cpu_mask) { return -1
 static inline void sbi_init(void) {}
 #endif /* CONFIG_RISCV_SBI */
 
+unsigned long riscv_get_mvendorid(void);
+unsigned long riscv_get_marchid(void);
 unsigned long riscv_cached_mvendorid(unsigned int cpu_id);
 unsigned long riscv_cached_marchid(unsigned int cpu_id);
 unsigned long riscv_cached_mimpid(unsigned int cpu_id);
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index d11d6320fb0d..08319a819f32 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -139,6 +139,26 @@ int riscv_of_parent_hartid(struct device_node *node, unsigned long *hartid)
 	return -1;
 }
 
+unsigned long __init riscv_get_marchid(void)
+{
+#if IS_ENABLED(CONFIG_RISCV_SBI)
+	return sbi_spec_is_0_1() ? 0 : sbi_get_marchid();
+#elif IS_ENABLED(CONFIG_RISCV_M_MODE)
+	return csr_read(CSR_MARCHID);
+#endif
+	return 0;
+}
+
+unsigned long __init riscv_get_mvendorid(void)
+{
+#if IS_ENABLED(CONFIG_RISCV_SBI)
+	return sbi_spec_is_0_1() ? 0 : sbi_get_mvendorid();
+#elif IS_ENABLED(CONFIG_RISCV_M_MODE)
+	return csr_read(CSR_MVENDORID);
+#endif
+	return 0;
+}
+
 DEFINE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);
 
 unsigned long riscv_cached_mvendorid(unsigned int cpu_id)
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 3ed2359eae35..cd156adbeb66 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -490,6 +490,8 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
 	struct acpi_table_header *rhct;
 	acpi_status status;
 	unsigned int cpu;
+	u64 boot_vendorid;
+	u64 boot_archid;
 
 	if (!acpi_disabled) {
 		status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
@@ -497,9 +499,14 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
 			return;
 	}
 
+	boot_vendorid = riscv_get_mvendorid();
+	boot_archid = riscv_get_marchid();
+
 	for_each_possible_cpu(cpu) {
 		struct riscv_isainfo *isainfo = &hart_isa[cpu];
 		unsigned long this_hwcap = 0;
+		u64 this_vendorid;
+		u64 this_archid;
 
 		if (acpi_disabled) {
 			node = of_cpu_device_node_get(cpu);
@@ -514,12 +521,23 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
 				pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
 				continue;
 			}
+			if (of_property_read_u64(node, "riscv,vendorid", &this_vendorid) < 0) {
+				pr_warn("Unable to find \"riscv,vendorid\" devicetree entry, using boot hart mvendorid instead\n");
+				this_vendorid = boot_vendorid;
+			}
+
+			if (of_property_read_u64(node, "riscv,archid", &this_archid) < 0) {
+				pr_warn("Unable to find \"riscv,vendorid\" devicetree entry, using boot hart marchid instead\n");
+				this_archid = boot_archid;
+			}
 		} else {
 			rc = acpi_get_riscv_isa(rhct, cpu, &isa);
 			if (rc < 0) {
 				pr_warn("Unable to get ISA for the hart - %d\n", cpu);
 				continue;
 			}
+			this_vendorid = boot_vendorid;
+			this_archid = boot_archid;
 		}
 
 		riscv_parse_isa_string(&this_hwcap, isainfo, isa2hwcap, isa);
@@ -544,8 +562,8 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
 		 * CPU cores with the ratified spec will contain non-zero
 		 * marchid.
 		 */
-		if (acpi_disabled && riscv_cached_mvendorid(cpu) == THEAD_VENDOR_ID &&
-		    riscv_cached_marchid(cpu) == 0x0) {
+		if (acpi_disabled && this_vendorid == THEAD_VENDOR_ID &&
+		    this_archid == 0x0) {
 			this_hwcap &= ~isa2hwcap[RISCV_ISA_EXT_v];
 			clear_bit(RISCV_ISA_EXT_v, isainfo->isa);
 		}

-- 
2.44.0