[PATCH v2 13/17] riscv: vector: Support xtheadvector save/restore

Charlie Jenkins
2024-04-16T04:12:23Z

Use alternatives to add support for xtheadvector vector save/restore
routines.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
arch/riscv/Kconfig | 2 +
arch/riscv/Kconfig.vendor | 11 ++
arch/riscv/include/asm/csr.h | 6 +
arch/riscv/include/asm/switch_to.h | 2 +-
arch/riscv/include/asm/vector.h | 246 ++++++++++++++++++++++++++-------
arch/riscv/kernel/cpufeature.c | 2 +-
arch/riscv/kernel/kernel_mode_vector.c | 8 +-
arch/riscv/kernel/process.c | 4 +-
arch/riscv/kernel/signal.c | 6 +-
arch/riscv/kernel/vector.c | 35 +++--
10 files changed, 250 insertions(+), 72 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index be09c8836d56..fec86fba3acd 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -759,6 +759,8 @@ config RISCV_EFFICIENT_UNALIGNED_ACCESS

endchoice

+source "arch/riscv/Kconfig.vendor"
+
endmenu # "Platform type"

menu "Kernel features"
diff --git a/arch/riscv/Kconfig.vendor b/arch/riscv/Kconfig.vendor
new file mode 100644
index 000000000000..be7bd3b4d936
--- /dev/null
+++ b/arch/riscv/Kconfig.vendor
@@ -0,0 +1,11 @@
+config RISCV_ISA_XTHEADVECTOR
+ bool "xtheadvector extension support"
+ depends on RISCV_ISA_V
+ depends on FPU
+ default y
+ help
+ Say N here if you want to disable all xtheadvector related procedure
+ in the kernel. This will disable vector for any T-Head board that
+ contains xtheadvector rather than the standard vector.
+
+ If you don't know what to do here, say Y.
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index e5a35efd56e0..13657d096e7d 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -30,6 +30,12 @@
#define SR_VS_CLEAN _AC(0x00000400, UL)
#define SR_VS_DIRTY _AC(0x00000600, UL)

+#define SR_VS_THEAD _AC(0x01800000, UL) /* xtheadvector Status */
+#define SR_VS_OFF_THEAD _AC(0x00000000, UL)
+#define SR_VS_INITIAL_THEAD _AC(0x00800000, UL)
+#define SR_VS_CLEAN_THEAD _AC(0x01000000, UL)
+#define SR_VS_DIRTY_THEAD _AC(0x01800000, UL)
+
#define SR_XS _AC(0x00018000, UL) /* Extension Status */
#define SR_XS_OFF _AC(0x00000000, UL)
#define SR_XS_INITIAL _AC(0x00008000, UL)
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
index 7efdb0584d47..ada6b5cf2d94 100644
--- a/arch/riscv/include/asm/switch_to.h
+++ b/arch/riscv/include/asm/switch_to.h
@@ -78,7 +78,7 @@ do { \
struct task_struct *__next = (next); \
if (has_fpu()) \
__switch_to_fpu(__prev, __next); \
- if (has_vector()) \
+ if (has_vector() || has_xtheadvector()) \
__switch_to_vector(__prev, __next); \
((last) = __switch_to(__prev, __next)); \
} while (0)
diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h
index 731dcd0ed4de..9871f59c7cfc 100644
--- a/arch/riscv/include/asm/vector.h
+++ b/arch/riscv/include/asm/vector.h
@@ -18,6 +18,26 @@
#include <asm/cpufeature.h>
#include <asm/csr.h>
#include <asm/asm.h>
+#include <asm/vendorid_list.h>
+#include <asm/xtheadvector.h>
+
+#define __riscv_v_vstate_or(_val, TYPE) ({ \
+ typeof(_val) _res = _val; \
+ if (has_xtheadvector()) \
+ _res = (_res & ~SR_VS_THEAD) | SR_VS_##TYPE##_THEAD; \
+ else \
+ _res = (_res & ~SR_VS) | SR_VS_##TYPE; \
+ _res; \
+})
+
+#define __riscv_v_vstate_check(_val, TYPE) ({ \
+ bool _res; \
+ if (has_xtheadvector()) \
+ _res = ((_val) & SR_VS_THEAD) == SR_VS_##TYPE##_THEAD; \
+ else \
+ _res = ((_val) & SR_VS) == SR_VS_##TYPE; \
+ _res; \
+})

extern unsigned long riscv_v_vsize;
int riscv_v_setup_vsize(void);
@@ -40,39 +60,62 @@ static __always_inline bool has_vector(void)
return riscv_has_extension_unlikely(RISCV_ISA_EXT_v);
}

+static __always_inline bool has_xtheadvector_no_alternatives(void)
+{
+ if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR) && hart_isa_vendorid == THEAD_VENDOR_ID)
+ return riscv_isa_vendor_extension_available(NULL, XTHEADVECTOR);
+ else
+ return false;
+}
+
+static __always_inline bool has_xtheadvector(void)
+{
+ if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR))
+ return riscv_has_vendor_extension_unlikely(THEAD_VENDOR_ID,
+ RISCV_ISA_VENDOR_EXT_XTHEADVECTOR);
+ else
+ return false;
+}
+
static inline void __riscv_v_vstate_clean(struct pt_regs *regs)
{
- regs->status = (regs->status & ~SR_VS) | SR_VS_CLEAN;
+ regs->status = __riscv_v_vstate_or(regs->status, CLEAN);
}

static inline void __riscv_v_vstate_dirty(struct pt_regs *regs)
{
- regs->status = (regs->status & ~SR_VS) | SR_VS_DIRTY;
+ regs->status = __riscv_v_vstate_or(regs->status, DIRTY);
}

static inline void riscv_v_vstate_off(struct pt_regs *regs)
{
- regs->status = (regs->status & ~SR_VS) | SR_VS_OFF;
+ regs->status = __riscv_v_vstate_or(regs->status, OFF);
}

static inline void riscv_v_vstate_on(struct pt_regs *regs)
{
- regs->status = (regs->status & ~SR_VS) | SR_VS_INITIAL;
+ regs->status = __riscv_v_vstate_or(regs->status, INITIAL);
}

static inline bool riscv_v_vstate_query(struct pt_regs *regs)
{
- return (regs->status & SR_VS) != 0;
+ return !__riscv_v_vstate_check(regs->status, OFF);
}

static __always_inline void riscv_v_enable(void)
{
- csr_set(CSR_SSTATUS, SR_VS);
+ if (has_xtheadvector())
+ csr_set(CSR_SSTATUS, SR_VS_THEAD);
+ else
+ csr_set(CSR_SSTATUS, SR_VS);
}

static __always_inline void riscv_v_disable(void)
{
- csr_clear(CSR_SSTATUS, SR_VS);
+ if (has_xtheadvector())
+ csr_clear(CSR_SSTATUS, SR_VS_THEAD);
+ else
+ csr_clear(CSR_SSTATUS, SR_VS);
}

static __always_inline void __vstate_csr_save(struct __riscv_v_ext_state *dest)
@@ -81,10 +124,47 @@ static __always_inline void __vstate_csr_save(struct __riscv_v_ext_state *dest)
"csrr %0, " __stringify(CSR_VSTART) "\n\t"
"csrr %1, " __stringify(CSR_VTYPE) "\n\t"
"csrr %2, " __stringify(CSR_VL) "\n\t"
- "csrr %3, " __stringify(CSR_VCSR) "\n\t"
- "csrr %4, " __stringify(CSR_VLENB) "\n\t"
: "=r" (dest->vstart), "=r" (dest->vtype), "=r" (dest->vl),
- "=r" (dest->vcsr), "=r" (dest->vlenb) : :);
+ "=r" (dest->vcsr) : :);
+
+ if (has_xtheadvector()) {
+ u32 tmp_vcsr;
+ bool restore_fpu = false;
+ unsigned long status = csr_read(CSR_SSTATUS);
+
+ /*
+ * CSR_VCSR is defined as
+ * [2:1] - vxrm[1:0]
+ * [0] - vxsat
+ * The earlier vector spec implemented by T-Head uses separate
+ * registers for the same bit-elements, so just combine those
+ * into the existing output field.
+ *
+ * Additionally T-Head cores need FS to be enabled when accessing
+ * the VXRM and VXSAT CSRs, otherwise ending in illegal instructions.
+ * Though the cores do not implement the VXRM and VXSAT fields in the
+ * FCSR CSR that vector-0.7.1 specifies.
+ */
+ if ((status & SR_FS) == SR_FS_OFF) {
+ csr_set(CSR_SSTATUS, (status & ~SR_FS) | SR_FS_CLEAN);
+ restore_fpu = true;
+ }
+
+ asm volatile (
+ "csrr %[tmp_vcsr], " __stringify(VCSR_VXRM) "\n\t"
+ "slliw %[vcsr], %[tmp_vcsr], " __stringify(VCSR_VXRM_SHIFT) "\n\t"
+ "csrr %[tmp_vcsr], " __stringify(VCSR_VXSAT) "\n\t"
+ "or %[vcsr], %[vcsr], %[tmp_vcsr]\n\t"
+ : [vcsr] "=r" (dest->vcsr), [tmp_vcsr] "=&r" (tmp_vcsr));
+
+ if (restore_fpu)
+ csr_set(CSR_SSTATUS, status);
+ } else {
+ asm volatile (
+ "csrr %[vcsr], " __stringify(CSR_VCSR) "\n\t"
+ "csrr %[vlenb], " __stringify(CSR_VLENB) "\n\t"
+ : [vcsr] "=r" (dest->vcsr), [vlenb] "=r" (dest->vlenb));
+ }
}

static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src)
@@ -95,9 +175,37 @@ static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src
"vsetvl x0, %2, %1\n\t"
".option pop\n\t"
"csrw " __stringify(CSR_VSTART) ", %0\n\t"
- "csrw " __stringify(CSR_VCSR) ", %3\n\t"
- : : "r" (src->vstart), "r" (src->vtype), "r" (src->vl),
- "r" (src->vcsr) :);
+ : : "r" (src->vstart), "r" (src->vtype), "r" (src->vl));
+
+ if (has_xtheadvector()) {
+ u32 tmp_vcsr;
+ bool restore_fpu = false;
+ unsigned long status = csr_read(CSR_SSTATUS);
+
+ /*
+ * Similar to __vstate_csr_save above, restore values for the
+ * separate VXRM and VXSAT CSRs from the vcsr variable.
+ */
+ if ((status & SR_FS) == SR_FS_OFF) {
+ csr_set(CSR_SSTATUS, (status & ~SR_FS) | SR_FS_CLEAN);
+ restore_fpu = true;
+ }
+
+ asm volatile (
+ "srliw %[tmp_vcsr], %[vcsr], " __stringify(VCSR_VXRM_SHIFT) "\n\t"
+ "andi %[tmp_vcsr], %[tmp_vcsr], " __stringify(VCSR_VXRM_MASK) "\n\t"
+ "csrw " __stringify(VCSR_VXRM) ", %[tmp_vcsr]\n\t"
+ "andi %[tmp_vcsr], %[vcsr], " __stringify(VCSR_VXSAT_MASK) "\n\t"
+ "csrw " __stringify(VCSR_VXSAT) ", %[tmp_vcsr]\n\t"
+ : [tmp_vcsr] "=&r" (tmp_vcsr) : [vcsr] "r" (src->vcsr));
+
+ if (restore_fpu)
+ csr_set(CSR_SSTATUS, status);
+ } else {
+ asm volatile (
+ "csrw " __stringify(CSR_VCSR) ", %[vcsr]\n\t"
+ : : [vcsr] "r" (src->vcsr));
+ }
}

static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to,
@@ -107,19 +215,33 @@ static inline void __riscv_v_vstate_save(struct __riscv_v_ext_state *save_to,

riscv_v_enable();
__vstate_csr_save(save_to);
- asm volatile (
- ".option push\n\t"
- ".option arch, +v\n\t"
- "vsetvli %0, x0, e8, m8, ta, ma\n\t"
- "vse8.v v0, (%1)\n\t"
- "add %1, %1, %0\n\t"
- "vse8.v v8, (%1)\n\t"
- "add %1, %1, %0\n\t"
- "vse8.v v16, (%1)\n\t"
- "add %1, %1, %0\n\t"
- "vse8.v v24, (%1)\n\t"
- ".option pop\n\t"
- : "=&r" (vl) : "r" (datap) : "memory");
+ if (has_xtheadvector()) {
+ asm volatile (
+ "mv t0, %0\n\t"
+ THEAD_VSETVLI_T4X0E8M8D1
+ THEAD_VSB_V_V0T0
+ "add t0, t0, t4\n\t"
+ THEAD_VSB_V_V0T0
+ "add t0, t0, t4\n\t"
+ THEAD_VSB_V_V0T0
+ "add t0, t0, t4\n\t"
+ THEAD_VSB_V_V0T0
+ : : "r" (datap) : "memory", "t0", "t4");
+ } else {
+ asm volatile (
+ ".option push\n\t"
+ ".option arch, +v\n\t"
+ "vsetvli %0, x0, e8, m8, ta, ma\n\t"
+ "vse8.v v0, (%1)\n\t"
+ "add %1, %1, %0\n\t"
+ "vse8.v v8, (%1)\n\t"
+ "add %1, %1, %0\n\t"
+ "vse8.v v16, (%1)\n\t"
+ "add %1, %1, %0\n\t"
+ "vse8.v v24, (%1)\n\t"
+ ".option pop\n\t"
+ : "=&r" (vl) : "r" (datap) : "memory");
+ }
riscv_v_disable();
}

@@ -129,55 +251,77 @@ static inline void __riscv_v_vstate_restore(struct __riscv_v_ext_state *restore_
unsigned long vl;

riscv_v_enable();
- asm volatile (
- ".option push\n\t"
- ".option arch, +v\n\t"
- "vsetvli %0, x0, e8, m8, ta, ma\n\t"
- "vle8.v v0, (%1)\n\t"
- "add %1, %1, %0\n\t"
- "vle8.v v8, (%1)\n\t"
- "add %1, %1, %0\n\t"
- "vle8.v v16, (%1)\n\t"
- "add %1, %1, %0\n\t"
- "vle8.v v24, (%1)\n\t"
- ".option pop\n\t"
- : "=&r" (vl) : "r" (datap) : "memory");
+ if (has_xtheadvector()) {
+ asm volatile (
+ "mv t0, %0\n\t"
+ THEAD_VSETVLI_T4X0E8M8D1
+ THEAD_VLB_V_V0T0
+ "add t0, t0, t4\n\t"
+ THEAD_VLB_V_V0T0
+ "add t0, t0, t4\n\t"
+ THEAD_VLB_V_V0T0
+ "add t0, t0, t4\n\t"
+ THEAD_VLB_V_V0T0
+ : : "r" (datap) : "memory", "t0", "t4");
+ } else {
+ asm volatile (
+ ".option push\n\t"
+ ".option arch, +v\n\t"
+ "vsetvli %0, x0, e8, m8, ta, ma\n\t"
+ "vle8.v v0, (%1)\n\t"
+ "add %1, %1, %0\n\t"
+ "vle8.v v8, (%1)\n\t"
+ "add %1, %1, %0\n\t"
+ "vle8.v v16, (%1)\n\t"
+ "add %1, %1, %0\n\t"
+ "vle8.v v24, (%1)\n\t"
+ ".option pop\n\t"
+ : "=&r" (vl) : "r" (datap) : "memory");
+ }
__vstate_csr_restore(restore_from);
riscv_v_disable();
}

static inline void __riscv_v_vstate_discard(void)
{
- unsigned long vl, vtype_inval = 1UL << (BITS_PER_LONG - 1);
+ unsigned long vtype_inval = 1UL << (BITS_PER_LONG - 1);

riscv_v_enable();
+ if (has_xtheadvector())
+ asm volatile (THEAD_VSETVLI_X0X0E8M8D1);
+ else
+ asm volatile (
+ ".option push\n\t"
+ ".option arch, +v\n\t"
+ "vsetvli x0, x0, e8, m8, ta, ma\n\t"
+ ".option pop\n\t");
+
asm volatile (
".option push\n\t"
".option arch, +v\n\t"
- "vsetvli %0, x0, e8, m8, ta, ma\n\t"
"vmv.v.i v0, -1\n\t"
"vmv.v.i v8, -1\n\t"
"vmv.v.i v16, -1\n\t"
"vmv.v.i v24, -1\n\t"
- "vsetvl %0, x0, %1\n\t"
+ "vsetvl x0, x0, %0\n\t"
".option pop\n\t"
- : "=&r" (vl) : "r" (vtype_inval) : "memory");
+ : : "r" (vtype_inval));
+
riscv_v_disable();
}

static inline void riscv_v_vstate_discard(struct pt_regs *regs)
{
- if ((regs->status & SR_VS) == SR_VS_OFF)
- return;
-
- __riscv_v_vstate_discard();
- __riscv_v_vstate_dirty(regs);
+ if (riscv_v_vstate_query(regs)) {
+ __riscv_v_vstate_discard();
+ __riscv_v_vstate_dirty(regs);
+ }
}

static inline void riscv_v_vstate_save(struct __riscv_v_ext_state *vstate,
struct pt_regs *regs)
{
- if ((regs->status & SR_VS) == SR_VS_DIRTY) {
+ if (__riscv_v_vstate_check(regs->status, DIRTY)) {
__riscv_v_vstate_save(vstate, vstate->datap);
__riscv_v_vstate_clean(regs);
}
@@ -186,7 +330,7 @@ static inline void riscv_v_vstate_save(struct __riscv_v_ext_state *vstate,
static inline void riscv_v_vstate_restore(struct __riscv_v_ext_state *vstate,
struct pt_regs *regs)
{
- if ((regs->status & SR_VS) != SR_VS_OFF) {
+ if (riscv_v_vstate_query(regs)) {
__riscv_v_vstate_restore(vstate, vstate->datap);
__riscv_v_vstate_clean(regs);
}
@@ -195,7 +339,7 @@ static inline void riscv_v_vstate_restore(struct __riscv_v_ext_state *vstate,
static inline void riscv_v_vstate_set_restore(struct task_struct *task,
struct pt_regs *regs)
{
- if ((regs->status & SR_VS) != SR_VS_OFF) {
+ if (riscv_v_vstate_query(regs)) {
set_tsk_thread_flag(task, TIF_RISCV_V_DEFER_RESTORE);
riscv_v_vstate_on(regs);
}
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 949c06970c4f..c62f4bf8b607 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -774,7 +774,7 @@ void __init riscv_fill_hwcap(void)
elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
}

- if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
+ if (elf_hwcap & COMPAT_HWCAP_ISA_V || has_xtheadvector_no_alternatives()) {
riscv_v_setup_vsize();
/*
* ISA string in device tree might have 'v' flag, but
diff --git a/arch/riscv/kernel/kernel_mode_vector.c b/arch/riscv/kernel/kernel_mode_vector.c
index 6afe80c7f03a..99972a48e86b 100644
--- a/arch/riscv/kernel/kernel_mode_vector.c
+++ b/arch/riscv/kernel/kernel_mode_vector.c
@@ -143,7 +143,7 @@ static int riscv_v_start_kernel_context(bool *is_nested)

/* Transfer the ownership of V from user to kernel, then save */
riscv_v_start(RISCV_PREEMPT_V | RISCV_PREEMPT_V_DIRTY);
- if ((task_pt_regs(current)->status & SR_VS) == SR_VS_DIRTY) {
+ if (__riscv_v_vstate_check(task_pt_regs(current)->status, DIRTY)) {
uvstate = &current->thread.vstate;
__riscv_v_vstate_save(uvstate, uvstate->datap);
}
@@ -160,7 +160,7 @@ asmlinkage void riscv_v_context_nesting_start(struct pt_regs *regs)
return;

depth = riscv_v_ctx_get_depth();
- if (depth == 0 && (regs->status & SR_VS) == SR_VS_DIRTY)
+ if (depth == 0 && __riscv_v_vstate_check(regs->status, DIRTY))
riscv_preempt_v_set_dirty();

riscv_v_ctx_depth_inc();
@@ -208,7 +208,7 @@ void kernel_vector_begin(void)
{
bool nested = false;

- if (WARN_ON(!has_vector()))
+ if (WARN_ON(!(has_vector() || has_xtheadvector())))
return;

BUG_ON(!may_use_simd());
@@ -236,7 +236,7 @@ EXPORT_SYMBOL_GPL(kernel_vector_begin);
*/
void kernel_vector_end(void)
{
- if (WARN_ON(!has_vector()))
+ if (WARN_ON(!(has_vector() || has_xtheadvector())))
return;

riscv_v_disable();
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 92922dbd5b5c..eabca86fc3c0 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -178,7 +178,7 @@ void flush_thread(void)
void arch_release_task_struct(struct task_struct *tsk)
{
/* Free the vector context of datap. */
- if (has_vector())
+ if (has_vector() || has_xtheadvector())
riscv_v_thread_free(tsk);
}

@@ -225,7 +225,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
p->thread.s[0] = 0;
}
p->thread.riscv_v_flags = 0;
- if (has_vector())
+ if (has_vector() || has_xtheadvector())
riscv_v_thread_alloc(p);
p->thread.ra = (unsigned long)ret_from_fork;
p->thread.sp = (unsigned long)childregs; /* kernel sp */
diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index 501e66debf69..5d3ba8e46807 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -188,7 +188,7 @@ static long restore_sigcontext(struct pt_regs *regs,

return 0;
case RISCV_V_MAGIC:
- if (!has_vector() || !riscv_v_vstate_query(regs) ||
+ if (!(has_vector() || has_xtheadvector()) || !riscv_v_vstate_query(regs) ||
size != riscv_v_sc_size)
return -EINVAL;

@@ -210,7 +210,7 @@ static size_t get_rt_frame_size(bool cal_all)

frame_size = sizeof(*frame);

- if (has_vector()) {
+ if (has_vector() || has_xtheadvector()) {
if (cal_all || riscv_v_vstate_query(task_pt_regs(current)))
total_context_size += riscv_v_sc_size;
}
@@ -283,7 +283,7 @@ static long setup_sigcontext(struct rt_sigframe __user *frame,
if (has_fpu())
err |= save_fp_state(regs, &sc->sc_fpregs);
/* Save the vector state. */
- if (has_vector() && riscv_v_vstate_query(regs))
+ if ((has_vector() || has_xtheadvector()) && riscv_v_vstate_query(regs))
err |= save_v_state(regs, (void __user **)&sc_ext_ptr);
/* Write zero to fp-reserved space and check it on restore_sigcontext */
err |= __put_user(0, &sc->sc_extdesc.reserved);
diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c
index 6727d1d3b8f2..f42eaa8178e9 100644
--- a/arch/riscv/kernel/vector.c
+++ b/arch/riscv/kernel/vector.c
@@ -33,10 +33,24 @@ int riscv_v_setup_vsize(void)
{
unsigned long this_vsize;

- /* There are 32 vector registers with vlenb length. */
- riscv_v_enable();
- this_vsize = csr_read(CSR_VLENB) * 32;
- riscv_v_disable();
+ /*
+ * This is called before alternatives have been patched so can't use
+ * riscv_has_vendor_extension_unlikely
+ */
+ if (has_xtheadvector_no_alternatives()) {
+ /*
+ * Although xtheadvector states that th.vlenb exists and
+ * overlaps with the vector 1.0 vlenb, an illegal instruction is
+ * raised if read. These systems all currently have a fixed
+ * vector length of 128, so hardcode that value.
+ */
+ this_vsize = 128;
+ } else {
+ /* There are 32 vector registers with vlenb length. */
+ riscv_v_enable();
+ this_vsize = csr_read(CSR_VLENB) * 32;
+ riscv_v_disable();
+ }

if (!riscv_v_vsize) {
riscv_v_vsize = this_vsize;
@@ -53,7 +67,7 @@ int riscv_v_setup_vsize(void)

void __init riscv_v_setup_ctx_cache(void)
{
- if (!has_vector())
+ if (!(has_vector() || has_xtheadvector()))
return;

riscv_v_user_cachep = kmem_cache_create_usercopy("riscv_vector_ctx",
@@ -174,7 +188,8 @@ bool riscv_v_first_use_handler(struct pt_regs *regs)
u32 insn = (u32)regs->badaddr;

/* Do not handle if V is not supported, or disabled */
- if (!(ELF_HWCAP & COMPAT_HWCAP_ISA_V))
+ if (!(ELF_HWCAP & COMPAT_HWCAP_ISA_V) &&
+ !(has_xtheadvector() && riscv_v_vstate_ctrl_user_allowed()))
return false;

/* If V has been enabled then it is not the first-use trap */
@@ -213,7 +228,7 @@ void riscv_v_vstate_ctrl_init(struct task_struct *tsk)
bool inherit;
int cur, next;

- if (!has_vector())
+ if (!(has_vector() || has_xtheadvector()))
return;

next = riscv_v_ctrl_get_next(tsk);
@@ -235,7 +250,7 @@ void riscv_v_vstate_ctrl_init(struct task_struct *tsk)

long riscv_v_vstate_ctrl_get_current(void)
{
- if (!has_vector())
+ if (!(has_vector() || has_xtheadvector()))
return -EINVAL;

return current->thread.vstate_ctrl & PR_RISCV_V_VSTATE_CTRL_MASK;
@@ -246,7 +261,7 @@ long riscv_v_vstate_ctrl_set_current(unsigned long arg)
bool inherit;
int cur, next;

- if (!has_vector())
+ if (!(has_vector() || has_xtheadvector()))
return -EINVAL;

if (arg & ~PR_RISCV_V_VSTATE_CTRL_MASK)
@@ -296,7 +311,7 @@ static struct ctl_table riscv_v_default_vstate_table[] = {

static int __init riscv_v_sysctl_init(void)
{
- if (has_vector())
+ if (has_vector() || has_xtheadvector())
if (!register_sysctl("abi", riscv_v_default_vstate_table))
return -EINVAL;
return 0;

--
2.44.0