[V2] cxl: Add support for ASB_Notify on POWER9

Message ID 1512143620-31330-1-git-send-email-clombard@linux.vnet.ibm.com
State New
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Series
  • [V2] cxl: Add support for ASB_Notify on POWER9
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Commit Message

Christophe Lombard Dec. 1, 2017, 3:53 p.m.
The POWER9 core supports a new feature: ASB_Notify which requires the
support of the Special Purpose Register: TIDR.

The ASB_Notify command, generated by the AFU, will attempt to
wake-up the host thread identified by the particular LPID:PID:TID.

This patch assign a unique TIDR (thread id) for the current thread which
will be used in the process element entry.

A next patch will handle a new kind of "compatible" property in the
device-tree (PHB DT node) indicating which version of CAPI and which
features are supported.

Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>

---
Changelog[v2]
 - Rebased to latest upstream.
 - Updated the ioctl interface.
 - Added a checking to allow updating the TIDR if a P9 chip is present.
---
 arch/powerpc/kernel/process.c |  2 ++
 drivers/misc/cxl/api.c        |  9 +++++++++
 drivers/misc/cxl/context.c    | 26 ++++++++++++++++++++++++++
 drivers/misc/cxl/cxl.h        |  4 ++++
 drivers/misc/cxl/cxllib.c     |  2 +-
 drivers/misc/cxl/file.c       | 24 ++++++++++++++++++++++++
 drivers/misc/cxl/native.c     |  2 +-
 include/uapi/misc/cxl.h       | 17 ++++++++++++++++-
 8 files changed, 83 insertions(+), 3 deletions(-)

Comments

Philippe Bergheaud Dec. 12, 2017, 3:39 p.m. | #1
On 01/12/2017 16:53, Christophe Lombard wrote:
> The POWER9 core supports a new feature: ASB_Notify which requires the
> support of the Special Purpose Register: TIDR.
>
> The ASB_Notify command, generated by the AFU, will attempt to
> wake-up the host thread identified by the particular LPID:PID:TID.
>
> This patch assign a unique TIDR (thread id) for the current thread which
> will be used in the process element entry.
>
> A next patch will handle a new kind of "compatible" property in the
> device-tree (PHB DT node) indicating which version of CAPI and which
> features are supported.
>
> Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
>

Reviewed-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>

Patch

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index bfdd783..b3489ab 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1738,6 +1738,7 @@  int copy_thread(unsigned long clone_flags, unsigned long usp,
 	kregs->nip = ppc_function_entry(f);
 	return 0;
 }
+EXPORT_SYMBOL_GPL(clear_thread_tidr);
 
 /*
  * Set up a thread for executing a new program
@@ -1913,6 +1914,7 @@  int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
 			| tsk->thread.fpexc_mode;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(set_thread_tidr);
 
 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 {
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index 7c11bad..605272c 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -684,3 +684,12 @@  void _cxl_cx4_teardown_msi_irqs(struct pci_dev *pdev)
 	}
 }
 /* Exported via cxl_base */
+
+int cxl_thread_tidr(struct cxl_context *ctx, u64 flags)
+{
+	if (!ctx)
+		return -EINVAL;
+
+	return cxl_context_thread_tidr(ctx, flags);
+}
+EXPORT_SYMBOL_GPL(cxl_thread_tidr);
diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 12a41b2..14e1a51 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -22,6 +22,7 @@ 
 #include <asm/cputable.h>
 #include <asm/current.h>
 #include <asm/copro.h>
+#include <asm/switch_to.h>
 
 #include "cxl.h"
 
@@ -42,6 +43,7 @@  int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
 
 	ctx->afu = afu;
 	ctx->master = master;
+	ctx->tid = 0;
 	ctx->pid = NULL; /* Set in start work ioctl */
 	mutex_init(&ctx->mapping_lock);
 	ctx->mapping = NULL;
@@ -362,3 +364,27 @@  void cxl_context_mm_count_put(struct cxl_context *ctx)
 	if (ctx->mm)
 		mmdrop(ctx->mm);
 }
+
+int cxl_context_thread_tidr(struct cxl_context *ctx, u64 flags)
+{
+	int rc = 0;
+
+	if (!cxl_is_power9())
+		return -ENODEV;
+
+	/* Clear any TIDR value assigned to the current thread */
+	if (flags == CXL_THREAD_TID_CLEAN) {
+		clear_thread_tidr(current);
+		ctx->tid = 0;
+	}
+
+	/* Assign a unique TIDR (thread id) for the current thread */
+	if (flags == CXL_THREAD_TID_ASSIGN) {
+		rc = set_thread_tidr(current);
+		if (!rc)
+			ctx->tid = current->thread.tidr;
+	}
+	pr_devel("%s: current tidr: %d\n", __func__, ctx->tid);
+
+	return rc;
+}
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index e46a406..e372291 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -561,6 +561,7 @@  struct cxl_context {
 	unsigned int sst_size, sst_lru;
 
 	wait_queue_head_t wq;
+	u32 tid;
 	/* use mm context associated with this pid for ds faults */
 	struct pid *pid;
 	spinlock_t lock; /* Protects pending_irq_mask, pending_fault and fault_addr */
@@ -1169,4 +1170,7 @@  void cxl_context_mm_count_get(struct cxl_context *ctx);
 /* Decrements the reference count to "struct mm_struct" */
 void cxl_context_mm_count_put(struct cxl_context *ctx);
 
+/* Handles an unique TIDR (thread id) for the current thread */
+int cxl_context_thread_tidr(struct cxl_context *ctx, u64 flags);
+
 #endif
diff --git a/drivers/misc/cxl/cxllib.c b/drivers/misc/cxl/cxllib.c
index dc9bc18..126d988 100644
--- a/drivers/misc/cxl/cxllib.c
+++ b/drivers/misc/cxl/cxllib.c
@@ -202,7 +202,7 @@  int cxllib_get_PE_attributes(struct task_struct *task,
 	} else {
 		attr->pid = 0;
 	}
-	attr->tid = 0;
+	attr->tid = current->thread.tidr;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(cxllib_get_PE_attributes);
diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index 76c0b0c..c9c79a9 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -300,6 +300,28 @@  static long afu_ioctl_get_afu_id(struct cxl_context *ctx,
 	return 0;
 }
 
+static long afu_ioctl_thread_tidr(struct cxl_context *ctx,
+				  struct cxl_ttid __user *uthreadtid)
+{
+	struct cxl_ttid threadtid = { 0 };
+	int rc;
+
+	if (copy_from_user(&threadtid, uthreadtid, sizeof(threadtid)))
+		return -EFAULT;
+
+	rc = cxl_context_thread_tidr(ctx, threadtid.flags);
+	if (rc)
+		goto out;
+
+	threadtid.tid = ctx->tid;
+	if (copy_to_user(uthreadtid, &threadtid, sizeof(threadtid)))
+		return -EFAULT;
+
+	rc = 0;
+out:
+	return rc;
+}
+
 long afu_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	struct cxl_context *ctx = file->private_data;
@@ -319,6 +341,8 @@  long afu_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case CXL_IOCTL_GET_AFU_ID:
 		return afu_ioctl_get_afu_id(ctx, (struct cxl_afu_id __user *)
 					    arg);
+	case CXL_IOCTL_THREAD_TID:
+		return afu_ioctl_thread_tidr(ctx, (struct cxl_ttid __user *)arg);
 	}
 	return -EINVAL;
 }
diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index 02b6b45..657c4a9 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -673,7 +673,7 @@  static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
 		pid = ctx->mm->context.id;
 	}
 
-	ctx->elem->common.tid = 0;
+	ctx->elem->common.tid = cpu_to_be32(ctx->tid);
 	ctx->elem->common.pid = cpu_to_be32(pid);
 
 	ctx->elem->sr = cpu_to_be64(calculate_sr(ctx));
diff --git a/include/uapi/misc/cxl.h b/include/uapi/misc/cxl.h
index 49e8fd0..e703597 100644
--- a/include/uapi/misc/cxl.h
+++ b/include/uapi/misc/cxl.h
@@ -76,12 +76,27 @@  struct cxl_adapter_image {
 	__u64 reserved4;
 };
 
+struct cxl_ttid {
+	__u64 flags;
+	__u64 tid;
+	__u64 reserved1;
+	__u64 reserved2;
+	__u64 reserved3;
+	__u64 reserved4;
+	__u64 reserved5;
+	__u64 reserved6;
+};
+
+#define CXL_THREAD_TID_CLEAN		0x0000000000000001ULL
+#define CXL_THREAD_TID_ASSIGN		0x0000000000000002ULL
+
 /* ioctl numbers */
 #define CXL_MAGIC 0xCA
 /* AFU devices */
 #define CXL_IOCTL_START_WORK		_IOW(CXL_MAGIC, 0x00, struct cxl_ioctl_start_work)
 #define CXL_IOCTL_GET_PROCESS_ELEMENT	_IOR(CXL_MAGIC, 0x01, __u32)
-#define CXL_IOCTL_GET_AFU_ID            _IOR(CXL_MAGIC, 0x02, struct cxl_afu_id)
+#define CXL_IOCTL_GET_AFU_ID		_IOR(CXL_MAGIC, 0x02, struct cxl_afu_id)
+#define CXL_IOCTL_THREAD_TID		_IOW(CXL_MAGIC, 0x03, struct cxl_ttid)
 /* adapter devices */
 #define CXL_IOCTL_DOWNLOAD_IMAGE        _IOW(CXL_MAGIC, 0x0A, struct cxl_adapter_image)
 #define CXL_IOCTL_VALIDATE_IMAGE        _IOW(CXL_MAGIC, 0x0B, struct cxl_adapter_image)