[V7] cxl: Add support for ASB_Notify on POWER9

Message ID 1515660925-10026-1-git-send-email-clombard@linux.vnet.ibm.com
State Accepted
Commit b1db551324f72fa14ad82ca31237a7ed418104df
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Series
  • [V7] cxl: Add support for ASB_Notify on POWER9
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Commit Message

christophe lombard Jan. 11, 2018, 8:55 a.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.

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

---
Changelog[v7]
 - Rebased to latest upstream.
 - Added boolean: "need to allocate a TIDR"
 - Released the mutex and mark the context as STARTED in case of error.

Changelog[v6]
 - Rebased to latest upstream.
 - Updated the ioctl interface.
 - Removed the updated ptrace.
 - Assigned a unique TIDR for the current thread at a lower level.

Changelog[v5]
 - Rebased to latest upstream.
 - Updated the ioctl interface.
 - Returned the tid in the ioctl structure.

Changelog[v4]
 - Rebased to latest upstream.
 - Updated the ioctl interface.
 - Removed the field tid in the context structure.

Changelog[v3]
 - Rebased to latest upstream.
 - Updated attr->tid field in cxllib_get_PE_attributes().

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 |  1 +
 drivers/misc/cxl/context.c    |  2 ++
 drivers/misc/cxl/cxl.h        |  3 +++
 drivers/misc/cxl/cxllib.c     |  3 ++-
 drivers/misc/cxl/file.c       | 15 +++++++++++++--
 drivers/misc/cxl/native.c     | 13 ++++++++++++-
 include/uapi/misc/cxl.h       | 10 ++++++----
 7 files changed, 39 insertions(+), 8 deletions(-)

Comments

Frederic Barrat Jan. 11, 2018, 5:40 p.m. | #1
Le 11/01/2018 à 09:55, Christophe Lombard a écrit :
> 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.
> 
> Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
> Reviewed-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>

Looks ok to me, thanks!

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


> Changelog[v7]
>   - Rebased to latest upstream.
>   - Added boolean: "need to allocate a TIDR"
>   - Released the mutex and mark the context as STARTED in case of error.
> 
> Changelog[v6]
>   - Rebased to latest upstream.
>   - Updated the ioctl interface.
>   - Removed the updated ptrace.
>   - Assigned a unique TIDR for the current thread at a lower level.
> 
> Changelog[v5]
>   - Rebased to latest upstream.
>   - Updated the ioctl interface.
>   - Returned the tid in the ioctl structure.
> 
> Changelog[v4]
>   - Rebased to latest upstream.
>   - Updated the ioctl interface.
>   - Removed the field tid in the context structure.
> 
> Changelog[v3]
>   - Rebased to latest upstream.
>   - Updated attr->tid field in cxllib_get_PE_attributes().
> 
> 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 |  1 +
>   drivers/misc/cxl/context.c    |  2 ++
>   drivers/misc/cxl/cxl.h        |  3 +++
>   drivers/misc/cxl/cxllib.c     |  3 ++-
>   drivers/misc/cxl/file.c       | 15 +++++++++++++--
>   drivers/misc/cxl/native.c     | 13 ++++++++++++-
>   include/uapi/misc/cxl.h       | 10 ++++++----
>   7 files changed, 39 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 72be0c3..1dc39dd 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1589,6 +1589,7 @@ int set_thread_tidr(struct task_struct *t)
> 
>   	return 0;
>   }
> +EXPORT_SYMBOL_GPL(set_thread_tidr);
> 
>   #endif /* CONFIG_PPC64 */
> 
> diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
> index 12a41b2..7ff315a 100644
> --- a/drivers/misc/cxl/context.c
> +++ b/drivers/misc/cxl/context.c
> @@ -45,6 +45,8 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
>   	ctx->pid = NULL; /* Set in start work ioctl */
>   	mutex_init(&ctx->mapping_lock);
>   	ctx->mapping = NULL;
> +	ctx->tidr = 0;
> +	ctx->assign_tidr = false;
> 
>   	if (cxl_is_power8()) {
>   		spin_lock_init(&ctx->sste_lock);
> diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
> index e46a406..53149fb 100644
> --- a/drivers/misc/cxl/cxl.h
> +++ b/drivers/misc/cxl/cxl.h
> @@ -630,6 +630,9 @@ struct cxl_context {
>   	struct list_head extra_irq_contexts;
> 
>   	struct mm_struct *mm;
> +
> +	u16 tidr;
> +	bool assign_tidr;
>   };
> 
>   struct cxl_irq_info;
> diff --git a/drivers/misc/cxl/cxllib.c b/drivers/misc/cxl/cxllib.c
> index dc9bc18..30ccba4 100644
> --- a/drivers/misc/cxl/cxllib.c
> +++ b/drivers/misc/cxl/cxllib.c
> @@ -199,10 +199,11 @@ int cxllib_get_PE_attributes(struct task_struct *task,
>   		 */
>   		attr->pid = mm->context.id;
>   		mmput(mm);
> +		attr->tid = task->thread.tidr;
>   	} else {
>   		attr->pid = 0;
> +		attr->tid = 0;
>   	}
> -	attr->tid = 0;
>   	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..93fd381 100644
> --- a/drivers/misc/cxl/file.c
> +++ b/drivers/misc/cxl/file.c
> @@ -173,7 +173,7 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
>   	 * flags are set it's invalid
>   	 */
>   	if (work.reserved1 || work.reserved2 || work.reserved3 ||
> -	    work.reserved4 || work.reserved5 || work.reserved6 ||
> +	    work.reserved4 || work.reserved5 ||
>   	    (work.flags & ~CXL_START_WORK_ALL)) {
>   		rc = -EINVAL;
>   		goto out;
> @@ -186,12 +186,16 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
>   		rc =  -EINVAL;
>   		goto out;
>   	}
> +
>   	if ((rc = afu_register_irqs(ctx, work.num_interrupts)))
>   		goto out;
> 
>   	if (work.flags & CXL_START_WORK_AMR)
>   		amr = work.amr & mfspr(SPRN_UAMOR);
> 
> +	if (work.flags & CXL_START_WORK_TID)
> +		ctx->assign_tidr = true;
> +
>   	ctx->mmio_err_ff = !!(work.flags & CXL_START_WORK_ERR_FF);
> 
>   	/*
> @@ -263,8 +267,15 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
>   		goto out;
>   	}
> 
> -	ctx->status = STARTED;
>   	rc = 0;
> +	if (work.flags & CXL_START_WORK_TID) {
> +		work.tid = ctx->tidr;
> +		if (copy_to_user(uwork, &work, sizeof(work)))
> +			rc = -EFAULT;
> +	}
> +
> +	ctx->status = STARTED;
> +
>   out:
>   	mutex_unlock(&ctx->status_mutex);
>   	return rc;
> diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
> index 02b6b45..1b3d7c6 100644
> --- a/drivers/misc/cxl/native.c
> +++ b/drivers/misc/cxl/native.c
> @@ -16,6 +16,7 @@
>   #include <linux/uaccess.h>
>   #include <linux/delay.h>
>   #include <asm/synch.h>
> +#include <asm/switch_to.h>
>   #include <misc/cxl-base.h>
> 
>   #include "cxl.h"
> @@ -655,6 +656,7 @@ static void update_ivtes_directed(struct cxl_context *ctx)
>   static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
>   {
>   	u32 pid;
> +	int rc;
> 
>   	cxl_assign_psn_space(ctx);
> 
> @@ -673,7 +675,16 @@ static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
>   		pid = ctx->mm->context.id;
>   	}
> 
> -	ctx->elem->common.tid = 0;
> +	/* Assign a unique TIDR (thread id) for the current thread */
> +	if (!(ctx->tidr) && (ctx->assign_tidr)) {
> +		rc = set_thread_tidr(current);
> +		if (rc)
> +			return -ENODEV;
> +		ctx->tidr = current->thread.tidr;
> +		pr_devel("%s: current tidr: %d\n", __func__, ctx->tidr);
> +	}
> +
> +	ctx->elem->common.tid = cpu_to_be32(ctx->tidr);
>   	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..56376d3 100644
> --- a/include/uapi/misc/cxl.h
> +++ b/include/uapi/misc/cxl.h
> @@ -20,20 +20,22 @@ struct cxl_ioctl_start_work {
>   	__u64 work_element_descriptor;
>   	__u64 amr;
>   	__s16 num_interrupts;
> -	__s16 reserved1;
> -	__s32 reserved2;
> +	__u16 tid;
> +	__s32 reserved1;
> +	__u64 reserved2;
>   	__u64 reserved3;
>   	__u64 reserved4;
>   	__u64 reserved5;
> -	__u64 reserved6;
>   };
> 
>   #define CXL_START_WORK_AMR		0x0000000000000001ULL
>   #define CXL_START_WORK_NUM_IRQS		0x0000000000000002ULL
>   #define CXL_START_WORK_ERR_FF		0x0000000000000004ULL
> +#define CXL_START_WORK_TID		0x0000000000000008ULL
>   #define CXL_START_WORK_ALL		(CXL_START_WORK_AMR |\
>   					 CXL_START_WORK_NUM_IRQS |\
> -					 CXL_START_WORK_ERR_FF)
> +					 CXL_START_WORK_ERR_FF |\
> +					 CXL_START_WORK_TID)
> 
> 
>   /* Possible modes that an afu can be in */
>
Vaibhav Jain Jan. 12, 2018, 8:51 a.m. | #2
Christophe Lombard <clombard@linux.vnet.ibm.com> writes:

> 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.
>
> Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
> Reviewed-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>
>
Reviewed-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Andrew Donnellan Jan. 15, 2018, 7:29 a.m. | #3
On 11/01/18 19:55, 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.
> 
> Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
> Reviewed-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> 
> ---
> Changelog[v7]
>   - Rebased to latest upstream.
>   - Added boolean: "need to allocate a TIDR"
>   - Released the mutex and mark the context as STARTED in case of error.
> 
> Changelog[v6]
>   - Rebased to latest upstream.
>   - Updated the ioctl interface.
>   - Removed the updated ptrace.
>   - Assigned a unique TIDR for the current thread at a lower level.
> 
> Changelog[v5]
>   - Rebased to latest upstream.
>   - Updated the ioctl interface.
>   - Returned the tid in the ioctl structure.
> 
> Changelog[v4]
>   - Rebased to latest upstream.
>   - Updated the ioctl interface.
>   - Removed the field tid in the context structure.
> 
> Changelog[v3]
>   - Rebased to latest upstream.
>   - Updated attr->tid field in cxllib_get_PE_attributes().
> 
> 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 |  1 +
>   drivers/misc/cxl/context.c    |  2 ++
>   drivers/misc/cxl/cxl.h        |  3 +++
>   drivers/misc/cxl/cxllib.c     |  3 ++-
>   drivers/misc/cxl/file.c       | 15 +++++++++++++--
>   drivers/misc/cxl/native.c     | 13 ++++++++++++-
>   include/uapi/misc/cxl.h       | 10 ++++++----
>   7 files changed, 39 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 72be0c3..1dc39dd 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1589,6 +1589,7 @@ int set_thread_tidr(struct task_struct *t)
> 
>   	return 0;
>   }
> +EXPORT_SYMBOL_GPL(set_thread_tidr);
> 
>   #endif /* CONFIG_PPC64 */
> 
> diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
> index 12a41b2..7ff315a 100644
> --- a/drivers/misc/cxl/context.c
> +++ b/drivers/misc/cxl/context.c
> @@ -45,6 +45,8 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
>   	ctx->pid = NULL; /* Set in start work ioctl */
>   	mutex_init(&ctx->mapping_lock);
>   	ctx->mapping = NULL;
> +	ctx->tidr = 0;
> +	ctx->assign_tidr = false;
> 
>   	if (cxl_is_power8()) {
>   		spin_lock_init(&ctx->sste_lock);
> diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
> index e46a406..53149fb 100644
> --- a/drivers/misc/cxl/cxl.h
> +++ b/drivers/misc/cxl/cxl.h
> @@ -630,6 +630,9 @@ struct cxl_context {
>   	struct list_head extra_irq_contexts;
> 
>   	struct mm_struct *mm;
> +
> +	u16 tidr;
> +	bool assign_tidr;
>   };
> 
>   struct cxl_irq_info;
> diff --git a/drivers/misc/cxl/cxllib.c b/drivers/misc/cxl/cxllib.c
> index dc9bc18..30ccba4 100644
> --- a/drivers/misc/cxl/cxllib.c
> +++ b/drivers/misc/cxl/cxllib.c
> @@ -199,10 +199,11 @@ int cxllib_get_PE_attributes(struct task_struct *task,
>   		 */
>   		attr->pid = mm->context.id;
>   		mmput(mm);
> +		attr->tid = task->thread.tidr;
>   	} else {
>   		attr->pid = 0;
> +		attr->tid = 0;
>   	}
> -	attr->tid = 0;
>   	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..93fd381 100644
> --- a/drivers/misc/cxl/file.c
> +++ b/drivers/misc/cxl/file.c
> @@ -173,7 +173,7 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
>   	 * flags are set it's invalid
>   	 */
>   	if (work.reserved1 || work.reserved2 || work.reserved3 ||
> -	    work.reserved4 || work.reserved5 || work.reserved6 ||
> +	    work.reserved4 || work.reserved5 ||
>   	    (work.flags & ~CXL_START_WORK_ALL)) {
>   		rc = -EINVAL;
>   		goto out;
> @@ -186,12 +186,16 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
>   		rc =  -EINVAL;
>   		goto out;
>   	}
> +
>   	if ((rc = afu_register_irqs(ctx, work.num_interrupts)))
>   		goto out;
> 
>   	if (work.flags & CXL_START_WORK_AMR)
>   		amr = work.amr & mfspr(SPRN_UAMOR);
> 
> +	if (work.flags & CXL_START_WORK_TID)
> +		ctx->assign_tidr = true;
> +
>   	ctx->mmio_err_ff = !!(work.flags & CXL_START_WORK_ERR_FF);
> 
>   	/*
> @@ -263,8 +267,15 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
>   		goto out;
>   	}
> 
> -	ctx->status = STARTED;
>   	rc = 0;
> +	if (work.flags & CXL_START_WORK_TID) {
> +		work.tid = ctx->tidr;
> +		if (copy_to_user(uwork, &work, sizeof(work)))
> +			rc = -EFAULT;
> +	}
> +
> +	ctx->status = STARTED;
> +
>   out:
>   	mutex_unlock(&ctx->status_mutex);
>   	return rc;
> diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
> index 02b6b45..1b3d7c6 100644
> --- a/drivers/misc/cxl/native.c
> +++ b/drivers/misc/cxl/native.c
> @@ -16,6 +16,7 @@
>   #include <linux/uaccess.h>
>   #include <linux/delay.h>
>   #include <asm/synch.h>
> +#include <asm/switch_to.h>
>   #include <misc/cxl-base.h>
> 
>   #include "cxl.h"
> @@ -655,6 +656,7 @@ static void update_ivtes_directed(struct cxl_context *ctx)
>   static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
>   {
>   	u32 pid;
> +	int rc;
> 
>   	cxl_assign_psn_space(ctx);
> 
> @@ -673,7 +675,16 @@ static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
>   		pid = ctx->mm->context.id;
>   	}
> 
> -	ctx->elem->common.tid = 0;
> +	/* Assign a unique TIDR (thread id) for the current thread */
> +	if (!(ctx->tidr) && (ctx->assign_tidr)) {
> +		rc = set_thread_tidr(current);
> +		if (rc)
> +			return -ENODEV;
> +		ctx->tidr = current->thread.tidr;
> +		pr_devel("%s: current tidr: %d\n", __func__, ctx->tidr);
> +	}
> +
> +	ctx->elem->common.tid = cpu_to_be32(ctx->tidr);
>   	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..56376d3 100644
> --- a/include/uapi/misc/cxl.h
> +++ b/include/uapi/misc/cxl.h
> @@ -20,20 +20,22 @@ struct cxl_ioctl_start_work {
>   	__u64 work_element_descriptor;
>   	__u64 amr;
>   	__s16 num_interrupts;
> -	__s16 reserved1;
> -	__s32 reserved2;
> +	__u16 tid;
> +	__s32 reserved1;
> +	__u64 reserved2;
>   	__u64 reserved3;
>   	__u64 reserved4;
>   	__u64 reserved5;
> -	__u64 reserved6;
>   };
> 
>   #define CXL_START_WORK_AMR		0x0000000000000001ULL
>   #define CXL_START_WORK_NUM_IRQS		0x0000000000000002ULL
>   #define CXL_START_WORK_ERR_FF		0x0000000000000004ULL
> +#define CXL_START_WORK_TID		0x0000000000000008ULL
>   #define CXL_START_WORK_ALL		(CXL_START_WORK_AMR |\
>   					 CXL_START_WORK_NUM_IRQS |\
> -					 CXL_START_WORK_ERR_FF)
> +					 CXL_START_WORK_ERR_FF |\
> +					 CXL_START_WORK_TID)
> 
> 
>   /* Possible modes that an afu can be in */
>
Michael Ellerman Jan. 22, 2018, 3:34 a.m. | #4
On Thu, 2018-01-11 at 08:55:25 UTC, 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.
> 
> Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
> Reviewed-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>
> Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
> Reviewed-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
> Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/b1db551324f72fa14ad82ca31237a7

cheers

Patch

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 72be0c3..1dc39dd 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1589,6 +1589,7 @@  int set_thread_tidr(struct task_struct *t)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(set_thread_tidr);
 
 #endif /* CONFIG_PPC64 */
 
diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 12a41b2..7ff315a 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -45,6 +45,8 @@  int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
 	ctx->pid = NULL; /* Set in start work ioctl */
 	mutex_init(&ctx->mapping_lock);
 	ctx->mapping = NULL;
+	ctx->tidr = 0;
+	ctx->assign_tidr = false;
 
 	if (cxl_is_power8()) {
 		spin_lock_init(&ctx->sste_lock);
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index e46a406..53149fb 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -630,6 +630,9 @@  struct cxl_context {
 	struct list_head extra_irq_contexts;
 
 	struct mm_struct *mm;
+
+	u16 tidr;
+	bool assign_tidr;
 };
 
 struct cxl_irq_info;
diff --git a/drivers/misc/cxl/cxllib.c b/drivers/misc/cxl/cxllib.c
index dc9bc18..30ccba4 100644
--- a/drivers/misc/cxl/cxllib.c
+++ b/drivers/misc/cxl/cxllib.c
@@ -199,10 +199,11 @@  int cxllib_get_PE_attributes(struct task_struct *task,
 		 */
 		attr->pid = mm->context.id;
 		mmput(mm);
+		attr->tid = task->thread.tidr;
 	} else {
 		attr->pid = 0;
+		attr->tid = 0;
 	}
-	attr->tid = 0;
 	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..93fd381 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -173,7 +173,7 @@  static long afu_ioctl_start_work(struct cxl_context *ctx,
 	 * flags are set it's invalid
 	 */
 	if (work.reserved1 || work.reserved2 || work.reserved3 ||
-	    work.reserved4 || work.reserved5 || work.reserved6 ||
+	    work.reserved4 || work.reserved5 ||
 	    (work.flags & ~CXL_START_WORK_ALL)) {
 		rc = -EINVAL;
 		goto out;
@@ -186,12 +186,16 @@  static long afu_ioctl_start_work(struct cxl_context *ctx,
 		rc =  -EINVAL;
 		goto out;
 	}
+
 	if ((rc = afu_register_irqs(ctx, work.num_interrupts)))
 		goto out;
 
 	if (work.flags & CXL_START_WORK_AMR)
 		amr = work.amr & mfspr(SPRN_UAMOR);
 
+	if (work.flags & CXL_START_WORK_TID)
+		ctx->assign_tidr = true;
+
 	ctx->mmio_err_ff = !!(work.flags & CXL_START_WORK_ERR_FF);
 
 	/*
@@ -263,8 +267,15 @@  static long afu_ioctl_start_work(struct cxl_context *ctx,
 		goto out;
 	}
 
-	ctx->status = STARTED;
 	rc = 0;
+	if (work.flags & CXL_START_WORK_TID) {
+		work.tid = ctx->tidr;
+		if (copy_to_user(uwork, &work, sizeof(work)))
+			rc = -EFAULT;
+	}
+
+	ctx->status = STARTED;
+
 out:
 	mutex_unlock(&ctx->status_mutex);
 	return rc;
diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index 02b6b45..1b3d7c6 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -16,6 +16,7 @@ 
 #include <linux/uaccess.h>
 #include <linux/delay.h>
 #include <asm/synch.h>
+#include <asm/switch_to.h>
 #include <misc/cxl-base.h>
 
 #include "cxl.h"
@@ -655,6 +656,7 @@  static void update_ivtes_directed(struct cxl_context *ctx)
 static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
 {
 	u32 pid;
+	int rc;
 
 	cxl_assign_psn_space(ctx);
 
@@ -673,7 +675,16 @@  static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
 		pid = ctx->mm->context.id;
 	}
 
-	ctx->elem->common.tid = 0;
+	/* Assign a unique TIDR (thread id) for the current thread */
+	if (!(ctx->tidr) && (ctx->assign_tidr)) {
+		rc = set_thread_tidr(current);
+		if (rc)
+			return -ENODEV;
+		ctx->tidr = current->thread.tidr;
+		pr_devel("%s: current tidr: %d\n", __func__, ctx->tidr);
+	}
+
+	ctx->elem->common.tid = cpu_to_be32(ctx->tidr);
 	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..56376d3 100644
--- a/include/uapi/misc/cxl.h
+++ b/include/uapi/misc/cxl.h
@@ -20,20 +20,22 @@  struct cxl_ioctl_start_work {
 	__u64 work_element_descriptor;
 	__u64 amr;
 	__s16 num_interrupts;
-	__s16 reserved1;
-	__s32 reserved2;
+	__u16 tid;
+	__s32 reserved1;
+	__u64 reserved2;
 	__u64 reserved3;
 	__u64 reserved4;
 	__u64 reserved5;
-	__u64 reserved6;
 };
 
 #define CXL_START_WORK_AMR		0x0000000000000001ULL
 #define CXL_START_WORK_NUM_IRQS		0x0000000000000002ULL
 #define CXL_START_WORK_ERR_FF		0x0000000000000004ULL
+#define CXL_START_WORK_TID		0x0000000000000008ULL
 #define CXL_START_WORK_ALL		(CXL_START_WORK_AMR |\
 					 CXL_START_WORK_NUM_IRQS |\
-					 CXL_START_WORK_ERR_FF)
+					 CXL_START_WORK_ERR_FF |\
+					 CXL_START_WORK_TID)
 
 
 /* Possible modes that an afu can be in */