[PATCH v12 17/17] riscv: prctl to enable vector commands

From: Chris Stillson
Date: Wed Sep 21 2022 - 17:56:28 EST

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This code makes enabling the vector extension on a riscv manchine
optional by adding an option to prctl() to allow a process to enable,
disable or query its vector context state.

-added prctl to enable/disable/query current vector state
-added actual function in riscv specific code to change/query the process
state
- Fixed problem with initial set of patches
(missing some EXPORT_SYMBOL() macro calls)
- rebased to 6.0-rc1
---
arch/riscv/configs/defconfig | 6 ++++++
arch/riscv/include/asm/kvm_vcpu_vector.h | 8 ++++----
arch/riscv/include/asm/processor.h | 6 ++++++
arch/riscv/include/asm/switch_to.h | 11 +++++++++++
arch/riscv/kernel/cpufeature.c | 3 ++-
arch/riscv/kernel/process.c | 20 +++++++++++++++++++-
arch/riscv/kvm/vcpu_vector.c | 14 +++++++-------
include/uapi/linux/prctl.h | 6 ++++++
kernel/sys.c | 7 +++++++
9 files changed, 68 insertions(+), 13 deletions(-)

diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index aed332a9d4ea..fce054286b1f 100644
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -209,3 +209,9 @@ CONFIG_RCU_EQS_DEBUG=y
# CONFIG_FTRACE is not set
# CONFIG_RUNTIME_TESTING_MENU is not set
CONFIG_MEMTEST=y
+CONFIG_ARCH_RV64I=y
+CONFIG_64BIT=y
+CONFIG_VECTOR=y
+CONFIG_ARCH_RV64I=y
+CONFIG_64BIT=y
+CONFIG_VECTOR=y
diff --git a/arch/riscv/include/asm/kvm_vcpu_vector.h b/arch/riscv/include/asm/kvm_vcpu_vector.h
index 1dcc1b2e05bb..c7101ff943a0 100644
--- a/arch/riscv/include/asm/kvm_vcpu_vector.h
+++ b/arch/riscv/include/asm/kvm_vcpu_vector.h
@@ -22,9 +22,9 @@ void __kvm_riscv_vector_save(struct kvm_cpu_context *context);
void __kvm_riscv_vector_restore(struct kvm_cpu_context *context);
void kvm_riscv_vcpu_vector_reset(struct kvm_vcpu *vcpu);
void kvm_riscv_vcpu_guest_vector_save(struct kvm_cpu_context *cntx,
- unsigned long isa);
+ unsigned long *isa);
void kvm_riscv_vcpu_guest_vector_restore(struct kvm_cpu_context *cntx,
- unsigned long isa);
+ unsigned long *isa);
void kvm_riscv_vcpu_host_vector_save(struct kvm_cpu_context *cntx);
void kvm_riscv_vcpu_host_vector_restore(struct kvm_cpu_context *cntx);
void kvm_riscv_vcpu_free_vector_context(struct kvm_vcpu *vcpu);
@@ -34,12 +34,12 @@ static inline void kvm_riscv_vcpu_vector_reset(struct kvm_vcpu *vcpu)
}

static inline void kvm_riscv_vcpu_guest_vector_save(struct kvm_cpu_context *cntx,
- unsigned long isa)
+ unsigned long *isa)
{
}

static inline void kvm_riscv_vcpu_guest_vector_restore(struct kvm_cpu_context *cntx,
- unsigned long isa)
+ unsigned long *isa)
{
}

diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index a09141ecf6aa..f2d0a91ce174 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -88,6 +88,12 @@ extern void riscv_fill_hwcap(void);
extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);

extern unsigned long signal_minsigstksz __ro_after_init;
+
+#ifdef CONFIG_VECTOR
+extern int rvv_proc_enable(unsigned long x);
+#define RVV_PROC_ENABLE(x) rvv_proc_enable(x)
+#endif
+
#endif /* __ASSEMBLY__ */

#endif /* _ASM_RISCV_PROCESSOR_H */
diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
index 527951c033d4..d9747450311c 100644
--- a/arch/riscv/include/asm/switch_to.h
+++ b/arch/riscv/include/asm/switch_to.h
@@ -80,6 +80,17 @@ extern unsigned long riscv_vsize;
extern void __vstate_save(struct __riscv_v_state *save_to, void *datap);
extern void __vstate_restore(struct __riscv_v_state *restore_from, void *datap);

+static inline bool vstate_query(struct pt_regs *regs)
+{
+ return (regs->status & SR_VS) != 0;
+}
+
+static inline void vstate_on(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ regs->status = (regs->status & ~(SR_VS)) | SR_VS_INITIAL;
+}
+
static inline void __vstate_clean(struct pt_regs *regs)
{
regs->status = (regs->status & ~(SR_VS)) | SR_VS_CLEAN;
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 0487ab19b234..3be469cb9266 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -37,6 +37,8 @@ __ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_fpu);
#include <asm/vector.h>
__ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_vector);
unsigned long riscv_vsize __read_mostly;
+EXPORT_SYMBOL(cpu_hwcap_vector);
+EXPORT_SYMBOL(riscv_vsize);
#endif

/**
@@ -346,4 +348,3 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
}
}
#endif
-}
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index e88a37fc77ed..a5a76d1374ec 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -15,6 +15,7 @@
#include <linux/tick.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
+#include <linux/prctl.h>

#include <asm/unistd.h>
#include <asm/processor.h>
@@ -134,7 +135,6 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
if (WARN_ON(!vstate->datap))
return;
}
- regs->status |= SR_VS_INITIAL;

/*
* Restore the initial value to the vector register
@@ -230,3 +229,22 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
p->thread.sp = (unsigned long)childregs; /* kernel sp */
return 0;
}
+
+#ifdef CONFIG_VECTOR
+int rvv_proc_enable(unsigned long x)
+{
+ switch (x) {
+ case PR_RVV_DISABLE:
+ vstate_off(current, task_pt_regs(current));
+ return 0;
+ case PR_RVV_ENABLE:
+ vstate_on(current, task_pt_regs(current));
+ return 0;
+ case PR_RVV_QUERY:
+ return vstate_query(task_pt_regs(current));
+ default:
+ return -(EINVAL);
+
+ }
+}
+#endif
diff --git a/arch/riscv/kvm/vcpu_vector.c b/arch/riscv/kvm/vcpu_vector.c
index 37bf4ffd47dd..9d1613da561a 100644
--- a/arch/riscv/kvm/vcpu_vector.c
+++ b/arch/riscv/kvm/vcpu_vector.c
@@ -20,7 +20,7 @@
extern unsigned long riscv_vsize;
void kvm_riscv_vcpu_vector_reset(struct kvm_vcpu *vcpu)
{
- unsigned long isa = vcpu->arch.isa;
+ unsigned long isa = *vcpu->arch.isa;
struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;

cntx->sstatus &= ~SR_VS;
@@ -39,20 +39,20 @@ static void kvm_riscv_vcpu_vector_clean(struct kvm_cpu_context *cntx)
}

void kvm_riscv_vcpu_guest_vector_save(struct kvm_cpu_context *cntx,
- unsigned long isa)
+ unsigned long *isa)
{
if ((cntx->sstatus & SR_VS) == SR_VS_DIRTY) {
- if (riscv_isa_extension_available(&isa, v))
+ if (riscv_isa_extension_available(isa, v))
__kvm_riscv_vector_save(cntx);
kvm_riscv_vcpu_vector_clean(cntx);
}
}

void kvm_riscv_vcpu_guest_vector_restore(struct kvm_cpu_context *cntx,
- unsigned long isa)
+ unsigned long *isa)
{
if ((cntx->sstatus & SR_VS) != SR_VS_OFF) {
- if (riscv_isa_extension_available(&isa, v))
+ if (riscv_isa_extension_available(isa, v))
__kvm_riscv_vector_restore(cntx);
kvm_riscv_vcpu_vector_clean(cntx);
}
@@ -122,7 +122,7 @@ int kvm_riscv_vcpu_get_reg_vector(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg,
unsigned long rtype)
{
- unsigned long isa = vcpu->arch.isa;
+ unsigned long isa = *vcpu->arch.isa;
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
@@ -149,7 +149,7 @@ int kvm_riscv_vcpu_set_reg_vector(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg,
unsigned long rtype)
{
- unsigned long isa = vcpu->arch.isa;
+ unsigned long isa = *vcpu->arch.isa;
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index a5e06dcbba13..8ea56e4c48f8 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -281,6 +281,12 @@ struct prctl_mm_map {
# define PR_SME_VL_LEN_MASK 0xffff
# define PR_SME_VL_INHERIT (1 << 17) /* inherit across exec */

+/* RISC-V V vector extension */
+#define PR_RVV_STATE 65
+# define PR_RVV_DISABLE 0
+# define PR_RVV_ENABLE 1
+# define PR_RVV_QUERY 2
+
#define PR_SET_VMA 0x53564d41
# define PR_SET_VMA_ANON_NAME 0

diff --git a/kernel/sys.c b/kernel/sys.c
index b911fa6d81ab..3049b1823273 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -138,6 +138,9 @@
#ifndef GET_TAGGED_ADDR_CTRL
# define GET_TAGGED_ADDR_CTRL() (-EINVAL)
#endif
+#ifndef RVV_PROC_ENABLE
+# define RVV_PROC_ENABLE(x) (-EINVAL)
+#endif

/*
* this is where the system-wide overflow UID and GID are defined, for
@@ -2620,6 +2623,10 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
error = sched_core_share_pid(arg2, arg3, arg4, arg5);
break;
#endif
+ case PR_RVV_STATE:
+ error = RVV_PROC_ENABLE(arg2);
+ break;
+
case PR_SET_VMA:
error = prctl_set_vma(arg2, arg3, arg4, arg5);
break;
--
2.25.1

Next message: Namhyung Kim: "[PATCH 2/2] perf: Use sample_flags for raw_data"
Previous message: Chris Stillson: "[PATCH v12 16/17] riscv: KVM: Add vector lazy save/restore support"
In reply to: Chris Stillson: "[PATCH v12 16/17] riscv: KVM: Add vector lazy save/restore support"
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