Re: [PATCH v5 5/7] ocxl: Expose the thread_id needed for wait on POWER9

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 12:06, Alastair D'Silva a écrit :



-Original Message-
From: Frederic Barrat <fbar...@linux.ibm.com>
Sent: Friday, 11 May 2018 7:25 PM
To: Alastair D'Silva <alast...@au1.ibm.com>; linuxppc-...@lists.ozlabs.org
Cc: linux-ker...@vger.kernel.org; linux-doc@vger.kernel.org;
mi...@neuling.org; vaib...@linux.vnet.ibm.com;
aneesh.ku...@linux.vnet.ibm.com; ma...@debian.org;
fe...@linux.vnet.ibm.com; pombreda...@nexb.com;
suka...@linux.vnet.ibm.com; npig...@gmail.com;
gre...@linuxfoundation.org; a...@arndb.de;
andrew.donnel...@au1.ibm.com; fbar...@linux.vnet.ibm.com;
cor...@lwn.net; Alastair D'Silva <alast...@d-silva.org>
Subject: Re: [PATCH v5 5/7] ocxl: Expose the thread_id needed for wait on
POWER9



Le 11/05/2018 à 08:13, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Ok, so we keep the limitation of having only one thread per context able to
call 'wait', even though we don't have to worry about depleting the pool of
TIDs any more. I think that's acceptable, though we don't really have a reason
to justify it any more. Any reason you want to keep it that way?



No strong reason, just trying to minimise the amount of changes. We can always 
expand the scope later, if we have a use-case for it.


ok. Agreed, it's not worth holding up this series, we can send a follow 
up patch.


  Fred



Fred



   drivers/misc/ocxl/context.c   |  5 ++-
   drivers/misc/ocxl/file.c  | 53 +++
   drivers/misc/ocxl/link.c  | 36 +
   drivers/misc/ocxl/ocxl_internal.h |  1 +
   include/misc/ocxl.h   |  9 ++
   include/uapi/misc/ocxl.h  |  8 +
   6 files changed, 111 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct

ocxl_afu *afu,

mutex_init(>xsl_error_lock);
mutex_init(>irq_lock);
idr_init(>irq_idr);
+   ctx->tidr = 0;
+
/*
 * Keep a reference on the AFU to make sure it's valid for the
 * duration of the life of the context @@ -65,6 +67,7 @@ int
ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
   {
int rc;

+   // Locks both status & tidr
mutex_lock(>status_mutex);
if (ctx->status != OPENED) {
rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64

amr)

}

rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-   current->mm->context.id, 0, amr, current->mm,
+   current->mm->context.id, ctx->tidr, amr, current-
mm,
xsl_fault_error, ctx);
if (rc)
goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c index
038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
   #include 
   #include 
   #include 
+#include 
+#include 
   #include "ocxl_internal.h"


@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct

ocxl_context *ctx,

return 0;
   }

+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+   struct ocxl_ioctl_p9_wait __user *uarg) {
+   struct ocxl_ioctl_p9_wait arg;
+
+   memset(, 0, sizeof(arg));
+
+   if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+   enum ocxl_context_status status;
+
+   // Locks both status & tidr
+   mutex_lock(>status_mutex);
+   if (!ctx->tidr) {
+   if (set_thread_tidr(current))
+   return -ENOENT;
+
+   ctx->tidr = current->thread.tidr;
+   }
+
+   status = ctx->status;
+   mutex_unlock(>status_mutex);
+
+   if (status == ATTACHED) {
+   int rc;
+   struct link *link = ctx->afu->fn->link;
+
+   rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+   if (rc)
+   return rc;
+   }
+
+   arg.thread_id = ctx->tidr;
+   } else
+   return -ENOENT;
+
+   if (copy_to_user(uarg, , sizeof(arg)))
+   return -EFAULT;
+
+   return 0;
+}
+#endif
+
   #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :

Re: [PATCH v5 7/7] ocxl: Document new OCXL IOCTLs

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 08:13, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Acked-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>



  Documentation/accelerators/ocxl.rst | 11 +++
  1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst 
b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..14cefc020e2d 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
Obtains configuration information from the card, such at the size of
MMIO areas, the AFU version, and the PASID for the current context.

+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on POWER9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+

  mmap
  



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Re: [PATCH v5 6/7] ocxl: Add an IOCTL so userspace knows what OCXL features are available

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 08:13, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

In order for a userspace AFU driver to call the POWER9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Acked-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>



  drivers/misc/ocxl/file.c | 25 +
  include/uapi/misc/ocxl.h |  6 ++
  2 files changed, 31 insertions(+)

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context 
*ctx,
  }
  #endif

+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+   struct ocxl_ioctl_features __user *uarg)
+{
+   struct ocxl_ioctl_features arg;
+
+   memset(, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+   if (cpu_has_feature(CPU_FTR_P9_TIDR))
+   arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+   if (copy_to_user(uarg, , sizeof(arg)))
+   return -EFAULT;
+
+   return 0;
+}
+
  #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" : \
x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" : \
x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :   \
x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :   \
x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :   \
x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :   \
+   x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :   \
"UNKNOWN")

  static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
break;
  #endif

+   case OCXL_IOCTL_GET_FEATURES:
+   rc = afu_ioctl_get_features(ctx,
+   (struct ocxl_ioctl_features __user *) args);
+   break;
+
default:
rc = -EINVAL;
}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 561e6f0dfcb7..97937cfa3baa 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,11 @@ struct ocxl_ioctl_p9_wait {
__u64 reserved3[3];
  };

+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT 0x01
+struct ocxl_ioctl_features {
+   __u64 flags[4];
+};
+
  struct ocxl_ioctl_irq_fd {
__u64 irq_offset;
__s32 eventfd;
@@ -70,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
  #define OCXL_IOCTL_IRQ_SET_FD _IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
  #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct 
ocxl_ioctl_metadata)
  #define OCXL_IOCTL_ENABLE_P9_WAIT _IOR(OCXL_MAGIC, 0x15, struct 
ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct 
ocxl_ioctl_features)

  #endif /* _UAPI_MISC_OCXL_H */



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Re: [PATCH v5 5/7] ocxl: Expose the thread_id needed for wait on POWER9

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 08:13, Alastair D'Silva a écrit :

From: Alastair D'Silva 

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva 
---


Ok, so we keep the limitation of having only one thread per context able 
to call 'wait', even though we don't have to worry about depleting the 
pool of TIDs any more. I think that's acceptable, though we don't really 
have a reason to justify it any more. Any reason you want to keep it 
that way?


  Fred



  drivers/misc/ocxl/context.c   |  5 ++-
  drivers/misc/ocxl/file.c  | 53 +++
  drivers/misc/ocxl/link.c  | 36 +
  drivers/misc/ocxl/ocxl_internal.h |  1 +
  include/misc/ocxl.h   |  9 ++
  include/uapi/misc/ocxl.h  |  8 +
  6 files changed, 111 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct 
ocxl_afu *afu,
mutex_init(>xsl_error_lock);
mutex_init(>irq_lock);
idr_init(>irq_idr);
+   ctx->tidr = 0;
+
/*
 * Keep a reference on the AFU to make sure it's valid for the
 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
  {
int rc;

+   // Locks both status & tidr
mutex_lock(>status_mutex);
if (ctx->status != OPENED) {
rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
}

rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-   current->mm->context.id, 0, amr, current->mm,
+   current->mm->context.id, ctx->tidr, amr, current->mm,
xsl_fault_error, ctx);
if (rc)
goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
  #include 
  #include 
  #include 
+#include 
+#include 
  #include "ocxl_internal.h"


@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context 
*ctx,
return 0;
  }

+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+   struct ocxl_ioctl_p9_wait __user *uarg)
+{
+   struct ocxl_ioctl_p9_wait arg;
+
+   memset(, 0, sizeof(arg));
+
+   if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+   enum ocxl_context_status status;
+
+   // Locks both status & tidr
+   mutex_lock(>status_mutex);
+   if (!ctx->tidr) {
+   if (set_thread_tidr(current))
+   return -ENOENT;
+
+   ctx->tidr = current->thread.tidr;
+   }
+
+   status = ctx->status;
+   mutex_unlock(>status_mutex);
+
+   if (status == ATTACHED) {
+   int rc;
+   struct link *link = ctx->afu->fn->link;
+
+   rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+   if (rc)
+   return rc;
+   }
+
+   arg.thread_id = ctx->tidr;
+   } else
+   return -ENOENT;
+
+   if (copy_to_user(uarg, , sizeof(arg)))
+   return -EFAULT;
+
+   return 0;
+}
+#endif
+
  #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" : \
x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" : \
x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :   \
x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :   \
x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :   \
+   x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :   \
"UNKNOWN")

  static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
(struct ocxl_ioctl_metadata __user *) args);
break;

+#ifdef CONFIG_PPC64
+   case OCXL_IOCTL_ENABLE_P9_WAIT:
+   rc = afu_ioctl_enable_p9_wait(ctx,
+   (struct ocxl_ioctl_p9_wait __user *) args);
+   break;
+#endif
+
default:
rc = -EINVAL;
}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -544,6 +544,42 @@ int

Re: [PATCH v5 3/7] powerpc: use task_pid_nr() for TID allocation

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 08:12, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.

In the unlikely event that 2 threads share the TID and are waiting,
all potential outcomes have been determined safe.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Thanks for adding the comment. It assumes the reader is aware that the 
TIDR value is only used for the notification using the 'wait' 
instruction, but that's likely to be the case.


Reviewed-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>



  arch/powerpc/include/asm/switch_to.h |   1 -
  arch/powerpc/kernel/process.c| 122 ++-
  2 files changed, 28 insertions(+), 95 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h 
b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
  extern int set_thread_uses_vas(void);

  extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);

  #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..c5b8e53acbae 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,41 @@ int set_thread_uses_vas(void)
  }

  #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
+/**
+ * Assign a TIDR (thread ID) for task @t and set it in the thread
+ * structure. For now, we only support setting TIDR for 'current' task.
   *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
+ * Since the TID value is a truncated form of it PID, it is possible
+ * (but unlikely) for 2 threads to have the same TID. In the unlikely event
+ * that 2 threads share the same TID and are waiting, one of the following
+ * cases will happen:
   *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
+ * 1. The correct thread is running, the wrong thread is not
+ * In this situation, the correct thread is woken and proceeds to pass it's
+ * condition check.
   *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
+ * 2. Neither threads are running
+ * In this situation, neither thread will be woken. When scheduled, the waiting
+ * threads will execute either a wait, which will return immediately, followed
+ * by a condition check, which will pass for the correct thread and fail
+ * for the wrong thread, or they will execute the condition check immediately.
   *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
+ * 3. The wrong thread is running, the correct thread is not
+ * The wrong thread will be woken, but will fail it's condition check and
+ * re-execute wait. The correct thread, when scheduled, will execute either
+ * it's condition check (which will pass), or wait, which returns immediately
+ * when called the first time after the thread is scheduled, followed by it's
+ * condition check (which will pass).
   *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *  For now, only threads that expect to be notified by the VAS
- *  hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT ((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-   int index;
-   int err;
-   unsigned long flags;
-
-again:
-   if (!ida_pre_get(_thread_ida, GFP_KERNEL))
-   return -ENOMEM;
-
-   spin_lock_irqsave(_thread_id_lock, flags);
-   err = ida_get_new_above(_thread_ida, 1, );
-   spin_unlock_irqrestore(_thread_id_lock, flags);
-
-   if (err == -EAGAIN)
-   goto again;
-   else if (err)
-   return err;
-
-   if (index > MAX_THREAD_CONTEXT) {
-

Re: [PATCH v5 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 08:13, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Acked-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>


  arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
  arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
  drivers/misc/ocxl/link.c  | 2 +-
  3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h 
b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void 
__iomem **dsisr,
  extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
void **platform_data);
  extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int 
pe_handle);

  extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
  extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c 
b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
  }
  EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);

-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
  {
struct spa_data *data = (struct spa_data *) platform_data;
int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int 
pe_handle)
rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
return rc;
  }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);

  int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
  {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 * On powerpc, the entry needs to be cleared from the context
 * cache of the NPU.
 */
-   rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+   rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
WARN_ON(rc);

pe_data = radix_tree_delete(>pe_tree, pe_handle);



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Re: [PATCH v5 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 08:12, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Reviewed-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>



  arch/powerpc/kernel/process.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct 
*old_thread,
mtspr(SPRN_TAR, new_thread->tar);
}

-   if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+   if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
old_thread->tidr != new_thread->tidr)
mtspr(SPRN_TIDR, new_thread->tidr);
  #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
if (!t->thread.tidr)
return;

-   if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+   if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
WARN_ON_ONCE(1);
return;
}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
  {
int rc;

-   if (!cpu_has_feature(CPU_FTR_ARCH_300))
+   if (!cpu_has_feature(CPU_FTR_P9_TIDR))
return -EINVAL;

if (t != current)



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Re: [PATCH v5 1/7] powerpc: Add TIDR CPU feature for POWER9

2018-05-11 Thread Frederic Barrat 



Le 11/05/2018 à 08:12, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Reviewed-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>




  arch/powerpc/include/asm/cputable.h | 3 ++-
  arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
  2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h 
b/arch/powerpc/include/asm/cputable.h
index 66fcab13c8b4..9c0a3083571b 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
  #define CPU_FTR_P9_TM_HV_ASSIST   
LONG_ASM_CONST(0x1000)
  #define CPU_FTR_P9_TM_XER_SO_BUG  LONG_ASM_CONST(0x2000)
  #define CPU_FTR_P9_TLBIE_BUG  LONG_ASM_CONST(0x4000)
+#define CPU_FTR_P9_TIDR
LONG_ASM_CONST(0x8000)

  #ifndef __ASSEMBLY__

@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-   CPU_FTR_P9_TLBIE_BUG)
+   CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
  #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 (~CPU_FTR_SAO))
  #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c 
b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 8ab51f6ca03a..41e5b69f 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -716,6 +716,7 @@ static __init void cpufeatures_cpu_quirks(void)
if ((version & 0x) == 0x004e) {
cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG;
+   cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;
}

/*



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Re: [PATCH v2 7/7] ocxl: Document new OCXL IOCTLs

2018-05-07 Thread Frederic Barrat 



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Acked-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>

  Fred



  Documentation/accelerators/ocxl.rst | 11 +++
  1 file changed, 11 insertions(+)

diff --git a/Documentation/accelerators/ocxl.rst 
b/Documentation/accelerators/ocxl.rst
index 7904adcc07fd..3b8d3b99795c 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,6 +157,17 @@ OCXL_IOCTL_GET_METADATA:
Obtains configuration information from the card, such at the size of
MMIO areas, the AFU version, and the PASID for the current context.

+OCXL_IOCTL_ENABLE_P9_WAIT:
+
+  Allows the AFU to wake a userspace thread executing 'wait'. Returns
+  information to userspace to allow it to configure the AFU. Note that
+  this is only available on Power 9.
+
+OCXL_IOCTL_GET_FEATURES:
+
+  Reports on which CPU features that affect OpenCAPI are usable from
+  userspace.
+
  mmap
  



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Re: [PATCH v2 6/7] ocxl: Add an IOCTL so userspace knows what CPU features are available

2018-05-07 Thread Frederic Barrat 



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

In order for a userspace AFU driver to call the Power9 specific
OCXL_IOCTL_ENABLE_P9_WAIT, it needs to verify that it can actually
make that call.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---
  Documentation/accelerators/ocxl.rst |  1 -
  drivers/misc/ocxl/file.c| 25 +
  include/uapi/misc/ocxl.h|  4 
  3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/Documentation/accelerators/ocxl.rst 
b/Documentation/accelerators/ocxl.rst
index ddcc58d01cfb..7904adcc07fd 100644
--- a/Documentation/accelerators/ocxl.rst
+++ b/Documentation/accelerators/ocxl.rst
@@ -157,7 +157,6 @@ OCXL_IOCTL_GET_METADATA:
Obtains configuration information from the card, such at the size of
MMIO areas, the AFU version, and the PASID for the current context.

-



Intended?

Other than that,
Acked-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>




  mmap
  

diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index eb409a469f21..33ae46ce0a8a 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -168,12 +168,32 @@ static long afu_ioctl_enable_p9_wait(struct ocxl_context 
*ctx,
  }
  #endif

+
+static long afu_ioctl_get_features(struct ocxl_context *ctx,
+   struct ocxl_ioctl_features __user *uarg)
+{
+   struct ocxl_ioctl_features arg;
+
+   memset(, 0, sizeof(arg));
+
+#ifdef CONFIG_PPC64
+   if (cpu_has_feature(CPU_FTR_P9_TIDR))
+   arg.flags[0] |= OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT;
+#endif
+
+   if (copy_to_user(uarg, , sizeof(arg)))
+   return -EFAULT;
+
+   return 0;
+}
+
  #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" : \
x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" : \
x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :   \
x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :   \
x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :   \
x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :   \
+   x == OCXL_IOCTL_GET_FEATURES ? "GET_FEATURES" :   \
"UNKNOWN")

  static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -239,6 +259,11 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
break;
  #endif

+   case OCXL_IOCTL_GET_FEATURES:
+   rc = afu_ioctl_get_features(ctx,
+   (struct ocxl_ioctl_features __user *) args);
+   break;
+
default:
rc = -EINVAL;
}
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index 8d2748e69c84..bb80f294b429 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -55,6 +55,9 @@ struct ocxl_ioctl_p9_wait {
__u64 reserved3[3];
  };

+#define OCXL_IOCTL_FEATURES_FLAGS0_P9_WAIT 0x01
+struct ocxl_ioctl_features {
+   __u64 flags[4];
  };

  struct ocxl_ioctl_irq_fd {
@@ -72,5 +75,6 @@ struct ocxl_ioctl_irq_fd {
  #define OCXL_IOCTL_IRQ_SET_FD _IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
  #define OCXL_IOCTL_GET_METADATA _IOR(OCXL_MAGIC, 0x14, struct 
ocxl_ioctl_metadata)
  #define OCXL_IOCTL_ENABLE_P9_WAIT _IOR(OCXL_MAGIC, 0x15, struct 
ocxl_ioctl_p9_wait)
+#define OCXL_IOCTL_GET_FEATURES _IOR(OCXL_MAGIC, 0x16, struct 
ocxl_ioctl_platform)

  #endif /* _UAPI_MISC_OCXL_H */



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Re: [PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9

2018-05-07 Thread Frederic Barrat 



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :

From: Alastair D'Silva 

In order to successfully issue as_notify, an AFU needs to know the TID
to notify, which in turn means that this information should be
available in userspace so it can be communicated to the AFU.

Signed-off-by: Alastair D'Silva 
---
  drivers/misc/ocxl/context.c   |  5 +++-
  drivers/misc/ocxl/file.c  | 53 +++
  drivers/misc/ocxl/link.c  | 36 ++
  drivers/misc/ocxl/ocxl_internal.h |  1 +
  include/misc/ocxl.h   |  9 +++
  include/uapi/misc/ocxl.h  | 10 
  6 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index 909e8807824a..95f74623113e 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -34,6 +34,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct 
ocxl_afu *afu,
mutex_init(>xsl_error_lock);
mutex_init(>irq_lock);
idr_init(>irq_idr);
+   ctx->tidr = 0;
+
/*
 * Keep a reference on the AFU to make sure it's valid for the
 * duration of the life of the context
@@ -65,6 +67,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
  {
int rc;

+   // Locks both status & tidr
mutex_lock(>status_mutex);
if (ctx->status != OPENED) {
rc = -EIO;
@@ -72,7 +75,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
}

rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-   current->mm->context.id, 0, amr, current->mm,
+   current->mm->context.id, ctx->tidr, amr, current->mm,
xsl_fault_error, ctx);
if (rc)
goto out;
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 038509e5d031..eb409a469f21 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -5,6 +5,8 @@
  #include 
  #include 
  #include 
+#include 
+#include 
  #include "ocxl_internal.h"


@@ -123,11 +125,55 @@ static long afu_ioctl_get_metadata(struct ocxl_context 
*ctx,
return 0;
  }

+#ifdef CONFIG_PPC64
+static long afu_ioctl_enable_p9_wait(struct ocxl_context *ctx,
+   struct ocxl_ioctl_p9_wait __user *uarg)
+{
+   struct ocxl_ioctl_p9_wait arg;
+
+   memset(, 0, sizeof(arg));
+
+   if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
+   enum ocxl_context_status status;
+
+   // Locks both status & tidr
+   mutex_lock(>status_mutex);
+   if (!ctx->tidr) {
+   if (set_thread_tidr(current))
+   return -ENOENT;
+
+   ctx->tidr = current->thread.tidr;
+   }



Now that we don't have the TIDR limit problem, I'm wondering if we 
cannot relax our rule a bit and have:
- first thread to enable will become the default thread and update the 
Process element

- any subsequent enable would just allocate the TIDR for the calling thread.

That way, more than one thread could be used for 'wait'.
Thoughts?

   Fred



+
+   status = ctx->status;
+   mutex_unlock(>status_mutex);
+
+   if (status == ATTACHED) {
+   int rc;
+   struct link *link = ctx->afu->fn->link;
+
+   rc = ocxl_link_update_pe(link, ctx->pasid, ctx->tidr);
+   if (rc)
+   return rc;
+   }
+
+   arg.thread_id = ctx->tidr;
+   } else
+   return -ENOENT;
+
+   if (copy_to_user(uarg, , sizeof(arg)))
+   return -EFAULT;
+
+   return 0;
+}
+#endif
+
  #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" : \
x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" : \
x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :   \
x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :   \
x == OCXL_IOCTL_GET_METADATA ? "GET_METADATA" :   \
+   x == OCXL_IOCTL_ENABLE_P9_WAIT ? "ENABLE_P9_WAIT" :   \
"UNKNOWN")

  static long afu_ioctl(struct file *file, unsigned int cmd,
@@ -186,6 +232,13 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
(struct ocxl_ioctl_metadata __user *) args);
break;

+#ifdef CONFIG_PPC64
+   case OCXL_IOCTL_ENABLE_P9_WAIT:
+   rc = afu_ioctl_enable_p9_wait(ctx,
+   (struct ocxl_ioctl_p9_wait __user *) args);
+   break;
+#endif
+
default:
rc = -EINVAL;
}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 656e8610eec2..88876ae8f330 100644
---

Re: [PATCH v2 4/7] ocxl: Rename pnv_ocxl_spa_remove_pe to clarify it's action

2018-05-07 Thread Frederic Barrat 



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

The function removes the process element from NPU cache.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Acked-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>



  arch/powerpc/include/asm/pnv-ocxl.h   | 2 +-
  arch/powerpc/platforms/powernv/ocxl.c | 4 ++--
  drivers/misc/ocxl/link.c  | 2 +-
  3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h 
b/arch/powerpc/include/asm/pnv-ocxl.h
index f6945d3bc971..208b5503f4ed 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -28,7 +28,7 @@ extern int pnv_ocxl_map_xsl_regs(struct pci_dev *dev, void 
__iomem **dsisr,
  extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
void **platform_data);
  extern void pnv_ocxl_spa_release(void *platform_data);
-extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
+extern int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int 
pe_handle);

  extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
  extern void pnv_ocxl_free_xive_irq(u32 irq);
diff --git a/arch/powerpc/platforms/powernv/ocxl.c 
b/arch/powerpc/platforms/powernv/ocxl.c
index fa9b53af3c7b..8c65aacda9c8 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -475,7 +475,7 @@ void pnv_ocxl_spa_release(void *platform_data)
  }
  EXPORT_SYMBOL_GPL(pnv_ocxl_spa_release);

-int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
+int pnv_ocxl_spa_remove_pe_from_cache(void *platform_data, int pe_handle)
  {
struct spa_data *data = (struct spa_data *) platform_data;
int rc;
@@ -483,7 +483,7 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int 
pe_handle)
rc = opal_npu_spa_clear_cache(data->phb_opal_id, data->bdfn, pe_handle);
return rc;
  }
-EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe_from_cache);

  int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
  {
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index f30790582dc0..656e8610eec2 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -599,7 +599,7 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 * On powerpc, the entry needs to be cleared from the context
 * cache of the NPU.
 */
-   rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+   rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
WARN_ON(rc);

pe_data = radix_tree_delete(>pe_tree, pe_handle);



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Re: [PATCH v2 3/7] powerpc: use task_pid_nr() for TID allocation

2018-05-07 Thread Frederic Barrat 



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

The current implementation of TID allocation, using a global IDR, may
result in an errant process starving the system of available TIDs.
Instead, use task_pid_nr(), as mentioned by the original author. The
scenario described which prevented it's use is not applicable, as
set_thread_tidr can only be called after the task struct has been
populated.



Here is how I understand what's going to happen if 2 threads are using 
the same TIDR value, which is possible with this patch (if unlikely):


1. waking up the wrong thread is not really a problem, as threads have 
to handle spurious wake up from the 'wait' instruction anyway, and must 
be using some other condition to know when to loop around the 'wait' 
instruction.


2. missing the right thread: if the wrong thread is on a CPU, and a 
wake_host_thread/as_notify is sent, the core will see a matching thread 
and will accept the command. The (open)capi adapter won't send an 
interrupt. The wrong thread is awaken, which is not a problem as 
discussed above. As the right thread to notify is not running, no harm 
is done either: as soon as the thread runs, it's supposed to check its 
condition (which will be met) or call 'wait', but 'wait' immediately 
returns when called the first time after a thread is scheduled.


So I believe we are ok. But I think it requires a huge comment with the 
above (at the minimum) :-)


With a comment:
Reviewed-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>

  Fred




Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---
  arch/powerpc/include/asm/switch_to.h |  1 -
  arch/powerpc/kernel/process.c| 97 +---
  2 files changed, 1 insertion(+), 97 deletions(-)

diff --git a/arch/powerpc/include/asm/switch_to.h 
b/arch/powerpc/include/asm/switch_to.h
index be8c9fa23983..5b03d8a82409 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -94,6 +94,5 @@ static inline void clear_task_ebb(struct task_struct *t)
  extern int set_thread_uses_vas(void);

  extern int set_thread_tidr(struct task_struct *t);
-extern void clear_thread_tidr(struct task_struct *t);

  #endif /* _ASM_POWERPC_SWITCH_TO_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b00da47699b..87f047fd2762 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1496,103 +1496,12 @@ int set_thread_uses_vas(void)
  }

  #ifdef CONFIG_PPC64
-static DEFINE_SPINLOCK(vas_thread_id_lock);
-static DEFINE_IDA(vas_thread_ida);
-
-/*
- * We need to assign a unique thread id to each thread in a process.
- *
- * This thread id, referred to as TIDR, and separate from the Linux's tgid,
- * is intended to be used to direct an ASB_Notify from the hardware to the
- * thread, when a suitable event occurs in the system.
- *
- * One such event is a "paste" instruction in the context of Fast Thread
- * Wakeup (aka Core-to-core wake up in the Virtual Accelerator Switchboard
- * (VAS) in POWER9.
- *
- * To get a unique TIDR per process we could simply reuse task_pid_nr() but
- * the problem is that task_pid_nr() is not yet available copy_thread() is
- * called. Fixing that would require changing more intrusive arch-neutral
- * code in code path in copy_process()?.
- *
- * Further, to assign unique TIDRs within each process, we need an atomic
- * field (or an IDR) in task_struct, which again intrudes into the arch-
- * neutral code. So try to assign globally unique TIDRs for now.
- *
- * NOTE: TIDR 0 indicates that the thread does not need a TIDR value.
- *  For now, only threads that expect to be notified by the VAS
- *  hardware need a TIDR value and we assign values > 0 for those.
- */
-#define MAX_THREAD_CONTEXT ((1 << 16) - 1)
-static int assign_thread_tidr(void)
-{
-   int index;
-   int err;
-   unsigned long flags;
-
-again:
-   if (!ida_pre_get(_thread_ida, GFP_KERNEL))
-   return -ENOMEM;
-
-   spin_lock_irqsave(_thread_id_lock, flags);
-   err = ida_get_new_above(_thread_ida, 1, );
-   spin_unlock_irqrestore(_thread_id_lock, flags);
-
-   if (err == -EAGAIN)
-   goto again;
-   else if (err)
-   return err;
-
-   if (index > MAX_THREAD_CONTEXT) {
-   spin_lock_irqsave(_thread_id_lock, flags);
-   ida_remove(_thread_ida, index);
-   spin_unlock_irqrestore(_thread_id_lock, flags);
-   return -ENOMEM;
-   }
-
-   return index;
-}
-
-static void free_thread_tidr(int id)
-{
-   unsigned long flags;
-
-   spin_lock_irqsave(_thread_id_lock, flags);
-   ida_remove(_thread_ida, id);
-   spin_unlock_irqrestore(_thread_id_lock, flags);
-}
-
-/*
- * Clear any TIDR value assigned to this thread.
- */
-void clear_thread_tidr(struct task_struct *t)
-{
-   if

Re: [PATCH v2 2/7] powerpc: Use TIDR CPU feature to control TIDR allocation

2018-05-07 Thread Frederic Barrat 



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :

From: Alastair D'Silva <alast...@d-silva.org>

Switch the use of TIDR on it's CPU feature, rather than assuming it
is available based on architecture.

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---


Reviewed-by: Frederic Barrat <fbar...@linux.vnet.ibm.com>



  arch/powerpc/kernel/process.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1237f13fed51..3b00da47699b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1154,7 +1154,7 @@ static inline void restore_sprs(struct thread_struct 
*old_thread,
mtspr(SPRN_TAR, new_thread->tar);
}

-   if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+   if (cpu_has_feature(CPU_FTR_P9_TIDR) &&
old_thread->tidr != new_thread->tidr)
mtspr(SPRN_TIDR, new_thread->tidr);
  #endif
@@ -1570,7 +1570,7 @@ void clear_thread_tidr(struct task_struct *t)
if (!t->thread.tidr)
return;

-   if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
+   if (!cpu_has_feature(CPU_FTR_P9_TIDR)) {
WARN_ON_ONCE(1);
return;
}
@@ -1593,7 +1593,7 @@ int set_thread_tidr(struct task_struct *t)
  {
int rc;

-   if (!cpu_has_feature(CPU_FTR_ARCH_300))
+   if (!cpu_has_feature(CPU_FTR_P9_TIDR))
return -EINVAL;

if (t != current)



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Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

2018-05-07 Thread Frederic Barrat 



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :

From: Alastair D'Silva 

This patch adds a CPU feature bit to show whether the CPU has
the TIDR register available, enabling as_notify/wait in userspace.

Signed-off-by: Alastair D'Silva 
---
  arch/powerpc/include/asm/cputable.h | 3 ++-
  arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
  2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/cputable.h 
b/arch/powerpc/include/asm/cputable.h
index 4e332f3531c5..54c4cbbe57b4 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
  #define CPU_FTR_P9_TM_HV_ASSIST   
LONG_ASM_CONST(0x1000)
  #define CPU_FTR_P9_TM_XER_SO_BUG  LONG_ASM_CONST(0x2000)
  #define CPU_FTR_P9_TLBIE_BUG  LONG_ASM_CONST(0x4000)
+#define CPU_FTR_P9_TIDR
LONG_ASM_CONST(0x8000)

  #ifndef __ASSEMBLY__

@@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
-   CPU_FTR_P9_TLBIE_BUG)
+   CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
  #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
 (~CPU_FTR_SAO))
  #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c 
b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 11a3a4fed3fb..10f8b7f55637 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
if ((version & 0x) == 0x004e) {
cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG; > +   
cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;



Isn't it redundant with adding the flag to CPU_FTRS_POWER9?

  Fred



}
  }



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