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    Subject[PATCH v2 5/7] ocxl: Expose the thread_id needed for wait on p9
    Date
    From: Alastair D'Silva <alastair@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 <alastair@d-silva.org>
    ---
    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(&ctx->xsl_error_lock);
    mutex_init(&ctx->irq_lock);
    idr_init(&ctx->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(&ctx->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 <linux/sched/signal.h>
    #include <linux/uaccess.h>
    #include <uapi/misc/ocxl.h>
    +#include <asm/reg.h>
    +#include <asm/switch_to.h>
    #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(&arg, 0, sizeof(arg));
    +
    + if (cpu_has_feature(CPU_FTR_P9_TIDR)) {
    + enum ocxl_context_status status;
    +
    + // Locks both status & tidr
    + mutex_lock(&ctx->status_mutex);
    + if (!ctx->tidr) {
    + if (set_thread_tidr(current))
    + return -ENOENT;
    +
    + ctx->tidr = current->thread.tidr;
    + }
    +
    + status = ctx->status;
    + mutex_unlock(&ctx->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, &arg, 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 ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
    }
    EXPORT_SYMBOL_GPL(ocxl_link_add_pe);

    +int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid)
    +{
    + struct link *link = (struct link *) link_handle;
    + struct spa *spa = link->spa;
    + struct ocxl_process_element *pe;
    + int pe_handle, rc;
    +
    + if (pasid > SPA_PASID_MAX)
    + return -EINVAL;
    +
    + pe_handle = pasid & SPA_PE_MASK;
    + pe = spa->spa_mem + pe_handle;
    +
    + mutex_lock(&spa->spa_lock);
    +
    + pe->tid = tid;
    +
    + /*
    + * The barrier makes sure the PE is updated
    + * before we clear the NPU context cache below, so that the
    + * old PE cannot be reloaded erroneously.
    + */
    + mb();
    +
    + /*
    + * hook to platform code
    + * On powerpc, the entry needs to be cleared from the context
    + * cache of the NPU.
    + */
    + rc = pnv_ocxl_spa_remove_pe_from_cache(link->platform_data, pe_handle);
    + WARN_ON(rc);
    +
    + mutex_unlock(&spa->spa_lock);
    + return rc;
    +}
    +
    int ocxl_link_remove_pe(void *link_handle, int pasid)
    {
    struct link *link = (struct link *) link_handle;
    diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
    index 5d421824afd9..6c6d4e61888e 100644
    --- a/drivers/misc/ocxl/ocxl_internal.h
    +++ b/drivers/misc/ocxl/ocxl_internal.h
    @@ -77,6 +77,7 @@ struct ocxl_context {
    struct ocxl_xsl_error xsl_error;
    struct mutex irq_lock;
    struct idr irq_idr;
    + __u16 tidr; // Thread ID used for P9 wait implementation
    };

    struct ocxl_process_element {
    diff --git a/include/misc/ocxl.h b/include/misc/ocxl.h
    index 51ccf76db293..9ff6ddc28e22 100644
    --- a/include/misc/ocxl.h
    +++ b/include/misc/ocxl.h
    @@ -188,6 +188,15 @@ extern int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
    void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
    void *xsl_err_data);

    +/**
    + * Update values within a Process Element
    + *
    + * link_handle: the link handle associated with the process element
    + * pasid: the PASID for the AFU context
    + * tid: the new thread id for the process element
    + */
    +extern int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
    +
    /*
    * Remove a Process Element from the Shared Process Area for a link
    */
    diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
    index 0af83d80fb3e..8d2748e69c84 100644
    --- a/include/uapi/misc/ocxl.h
    +++ b/include/uapi/misc/ocxl.h
    @@ -48,6 +48,15 @@ struct ocxl_ioctl_metadata {
    __u64 reserved[13]; // Total of 16*u64
    };

    +struct ocxl_ioctl_p9_wait {
    + __u16 thread_id; // The thread ID required to wake this thread
    + __u16 reserved1;
    + __u32 reserved2;
    + __u64 reserved3[3];
    +};
    +
    +};
    +
    struct ocxl_ioctl_irq_fd {
    __u64 irq_offset;
    __s32 eventfd;
    @@ -62,5 +71,6 @@ struct ocxl_ioctl_irq_fd {
    #define OCXL_IOCTL_IRQ_FREE _IOW(OCXL_MAGIC, 0x12, __u64)
    #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)

    #endif /* _UAPI_MISC_OCXL_H */
    --
    2.14.3
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