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Message-Id: <2E3C996E-C050-426F-878D-F25905E3C584@us.ibm.com>
Date: Mon, 7 Mar 2016 18:26:55 -0600
From: Matt Ochs <mrochs@...ibm.com>
To: Ian Munsie <imunsie@....ibm.com>
Cc: Michael Ellerman <michaele@....ibm.com>,
linux-kernel <linux-kernel@...r.kernel.org>,
Manoj Kumar <kumarmn@...ibm.com>,
linuxppc-dev <linuxppc-dev@...abs.org>,
Michael Neuling <mikey@...ling.org>
Subject: Re: [PATCH v2 1/2] cxl: Add mechanism for delivering AFU driver specific events
A couple of minor nits below...
> On Mar 7, 2016, at 12:59 PM, Ian Munsie <imunsie@....ibm.com> wrote:
>
> @@ -346,7 +350,7 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
>
> for (;;) {
> prepare_to_wait(&ctx->wq, &wait, TASK_INTERRUPTIBLE);
> - if (ctx_event_pending(ctx))
> + if (ctx_event_pending(ctx) || (ctx->status == CLOSED))
> break;
>
> if (!cxl_adapter_link_ok(ctx->afu->adapter)) {
> @@ -376,7 +380,14 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
> memset(&event, 0, sizeof(event));
> event.header.process_element = ctx->pe;
> event.header.size = sizeof(struct cxl_event_header);
> - if (ctx->pending_irq) {
> +
> + if (ctx->afu_driver_ops && ctx->afu_driver_ops->event_pending(ctx)) {
> + pr_devel("afu_read delivering AFU driver specific event\n");
> + event.header.type = CXL_EVENT_AFU_DRIVER;
> + ctx->afu_driver_ops->deliver_event(ctx, &event, sizeof(event));
> + WARN_ON(event.header.size > sizeof(event));
> +
> + } else if (ctx->pending_irq) {
> pr_devel("afu_read delivering AFU interrupt\n");
> event.header.size += sizeof(struct cxl_event_afu_interrupt);
> event.header.type = CXL_EVENT_AFU_INTERRUPT;
> @@ -384,6 +395,7 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
> clear_bit(event.irq.irq - 1, ctx->irq_bitmap);
> if (bitmap_empty(ctx->irq_bitmap, ctx->irq_count))
> ctx->pending_irq = false;
> +
> } else if (ctx->pending_fault) {
> pr_devel("afu_read delivering data storage fault\n");
> event.header.size += sizeof(struct cxl_event_data_storage);
> @@ -391,12 +403,14 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
> event.fault.addr = ctx->fault_addr;
> event.fault.dsisr = ctx->fault_dsisr;
> ctx->pending_fault = false;
> +
> } else if (ctx->pending_afu_err) {
> pr_devel("afu_read delivering afu error\n");
> event.header.size += sizeof(struct cxl_event_afu_error);
> event.header.type = CXL_EVENT_AFU_ERROR;
> event.afu_error.error = ctx->afu_err;
> ctx->pending_afu_err = false;
> +
Any reason for adding these extra lines as part of this commit?
> diff --git a/include/misc/cxl.h b/include/misc/cxl.h
> index f2ffe5b..f198a42 100644
> --- a/include/misc/cxl.h
> +++ b/include/misc/cxl.h
> @@ -210,4 +210,33 @@ ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
> void cxl_perst_reloads_same_image(struct cxl_afu *afu,
> bool perst_reloads_same_image);
>
> +/*
> + * AFU driver ops allows an AFU driver to create their own events to pass to
> + * userspace through the file descriptor as a simpler alternative to overriding
> + * the read() and poll() calls that works with the generic cxl events. These
> + * events are given priority over the generic cxl events, so will be delivered
so _they_ will be delivered
> + * first if multiple types of events are pending.
> + *
> + * even_pending() will be called by the cxl driver to check if an event is
> + * pending (e.g. in select/poll/read calls).
event_pending() <- missing 't'
> + *
> + * deliver_event() will be called to fill out a cxl_event structure with the
> + * driver specific event. The header will already have the type and
> + * process_element fields filled in, and header.size will be set to
> + * sizeof(struct cxl_event_header). The AFU driver can extend that size up to
> + * max_size (if an afu driver requires more space, they should submit a patch
> + * increasing the size in the struct cxl_event_afu_driver_reserved definition).
> + *
> + * Both of these calls are made with a spin lock held, so they must not sleep.
> + */
> +struct cxl_afu_driver_ops {
> + bool (*event_pending) (struct cxl_context *ctx);
> + void (*deliver_event) (struct cxl_context *ctx,
> + struct cxl_event *event, size_t max_size);
> +};
> +
> +/* Associate the above driver ops with a specific context */
> +void cxl_set_driver_ops(struct cxl_context *ctx,
> + struct cxl_afu_driver_ops *ops);
> +
> #endif /* _MISC_CXL_H */
> diff --git a/include/uapi/misc/cxl.h b/include/uapi/misc/cxl.h
> index 1e889aa..8b097db 100644
> --- a/include/uapi/misc/cxl.h
> +++ b/include/uapi/misc/cxl.h
> @@ -69,6 +69,7 @@ enum cxl_event_type {
> CXL_EVENT_AFU_INTERRUPT = 1,
> CXL_EVENT_DATA_STORAGE = 2,
> CXL_EVENT_AFU_ERROR = 3,
> + CXL_EVENT_AFU_DRIVER = 4,
> };
>
> struct cxl_event_header {
> @@ -100,12 +101,33 @@ struct cxl_event_afu_error {
> __u64 error;
> };
>
> +struct cxl_event_afu_driver_reserved {
> + /*
> + * Reserves space for AFU driver specific events. Not actually
> + * reserving any more space compared to other events as we can't know
> + * how much an AFU driver will need (but it is likely to be small). If
> + * your AFU driver needs more than this, please submit a patch
> + * increasing it as part of your driver submission.
> + *
> + * This is not ABI since the event header.size passed to the user for
> + * existing events is set in the read call to sizeof(cxl_event_header)
> + * + sizeof(whatever event is being dispatched) and will not increase
> + * just because this is, and the user is already required to use a 4K
> + * buffer on the read call. This is merely the size of the buffer
> + * passed between the cxl and AFU drivers.
> + *
> + * Of course the contents will be ABI, but that's up the AFU driver.
> + */
> + __u64 reserved[4];
> +};
> +
> struct cxl_event {
> struct cxl_event_header header;
> union {
> struct cxl_event_afu_interrupt irq;
> struct cxl_event_data_storage fault;
> struct cxl_event_afu_error afu_error;
> + struct cxl_event_afu_driver_reserved afu_driver_event;
> };
> };
>
> --
> 2.1.4
>
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> Linuxppc-dev@...ts.ozlabs.org
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