[PATCH v2 01/17] riscv: cpufeature: Fix thead vector hwcap removal

Charlie Jenkins
2024-04-16T04:12:40Z

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@rivosinc.com>
---
arch/riscv/include/asm/sbi.h | 2 ++
arch/riscv/kernel/cpu.c | 36 ++++++++++++++++++++++++++++++++----
arch/riscv/kernel/cpufeature.c | 12 ++++++++++--
3 files changed, 44 insertions(+), 6 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..8c8250b98752 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -139,6 +139,34 @@ int riscv_of_parent_hartid(struct device_node *node, unsigned long *hartid)
return -1;
}

+unsigned long __init riscv_get_marchid(void)
+{
+ struct riscv_cpuinfo *ci = this_cpu_ptr(&riscv_cpuinfo);
+
+#if IS_ENABLED(CONFIG_RISCV_SBI)
+ ci->marchid = sbi_spec_is_0_1() ? 0 : sbi_get_marchid();
+#elif IS_ENABLED(CONFIG_RISCV_M_MODE)
+ ci->marchid = csr_read(CSR_MARCHID);
+#else
+ ci->marchid = 0;
+#endif
+ return ci->marchid;
+}
+
+unsigned long __init riscv_get_mvendorid(void)
+{
+ struct riscv_cpuinfo *ci = this_cpu_ptr(&riscv_cpuinfo);
+
+#if IS_ENABLED(CONFIG_RISCV_SBI)
+ ci->mvendorid = sbi_spec_is_0_1() ? 0 : sbi_get_mvendorid();
+#elif IS_ENABLED(CONFIG_RISCV_M_MODE)
+ ci->mvendorid = csr_read(CSR_MVENDORID);
+#else
+ ci->mvendorid = 0;
+#endif
+ return ci->mvendorid;
+}
+
DEFINE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);

unsigned long riscv_cached_mvendorid(unsigned int cpu_id)
@@ -170,12 +198,12 @@ static int riscv_cpuinfo_starting(unsigned int cpu)
struct riscv_cpuinfo *ci = this_cpu_ptr(&riscv_cpuinfo);

#if IS_ENABLED(CONFIG_RISCV_SBI)
- ci->mvendorid = sbi_spec_is_0_1() ? 0 : sbi_get_mvendorid();
- ci->marchid = sbi_spec_is_0_1() ? 0 : sbi_get_marchid();
+ ci->mvendorid = ci->mvendorid ? ci->mvendorid : sbi_spec_is_0_1() ? 0 : sbi_get_mvendorid();
+ ci->marchid = ci->marchid ? ci->marchid : sbi_spec_is_0_1() ? 0 : sbi_get_marchid();
ci->mimpid = sbi_spec_is_0_1() ? 0 : sbi_get_mimpid();
#elif IS_ENABLED(CONFIG_RISCV_M_MODE)
- ci->mvendorid = csr_read(CSR_MVENDORID);
- ci->marchid = csr_read(CSR_MARCHID);
+ ci->mvendorid = ci->mvendorid ? ci->mvendorid : csr_read(CSR_MVENDORID);
+ ci->marchid = ci->marchid ? ci->marchid : csr_read(CSR_MARCHID);
ci->mimpid = csr_read(CSR_MIMPID);
#else
ci->mvendorid = 0;
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 3ed2359eae35..c6e27b45e192 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);
@@ -497,6 +499,13 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
return;
}

+ /*
+ * Naively assume that all harts have the same mvendorid/marchid as the
+ * boot hart.
+ */
+ 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;
@@ -544,8 +553,7 @@ 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 && boot_vendorid == THEAD_VENDOR_ID && boot_archid == 0x0) {
this_hwcap &= ~isa2hwcap[RISCV_ISA_EXT_v];
clear_bit(RISCV_ISA_EXT_v, isainfo->isa);
}