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Subject: Re: [PATCH v3 20/27] powerpc/powernv/pmem: Forward events to
 userspace
To:     "Alastair D'Silva" <alastair@au1.ibm.com>, alastair@d-silva.org
Cc:     "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        "Oliver O'Halloran" <oohall@gmail.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Andrew Donnellan <ajd@linux.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Rob Herring <robh@kernel.org>,
        Anton Blanchard <anton@ozlabs.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
        =?UTF-8?Q?C=c3=a9dric_Le_Goater?= <clg@kaod.org>,
        Anju T Sudhakar <anju@linux.vnet.ibm.com>,
        Hari Bathini <hbathini@linux.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kurz <groug@kaod.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Alexey Kardashevskiy <aik@ozlabs.ru>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-nvdimm@lists.01.org, linux-mm@kvack.org
References: <20200221032720.33893-1-alastair@au1.ibm.com>
 <20200221032720.33893-21-alastair@au1.ibm.com>
From:   Frederic Barrat <fbarrat@linux.ibm.com>
Date:   Wed, 4 Mar 2020 12:00:38 +0100
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Le 21/02/2020 à 04:27, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@d-silva.org>
> 
> Some of the interrupts that the card generates are better handled
> by the userspace daemon, in particular:
> Controller Hardware/Firmware Fatal
> Controller Dump Available
> Error Log available
> 
> This patch allows a userspace application to register an eventfd with
> the driver via SCM_IOCTL_EVENTFD to receive notifications of these
> interrupts.
> 
> Userspace can then identify what events have occurred by calling
> SCM_IOCTL_EVENT_CHECK and checking against the SCM_IOCTL_EVENT_FOO
> masks.
> 
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> ---
>   arch/powerpc/platforms/powernv/pmem/ocxl.c    | 216 ++++++++++++++++++
>   .../platforms/powernv/pmem/ocxl_internal.h    |   5 +
>   include/uapi/nvdimm/ocxl-pmem.h               |  16 ++
>   3 files changed, 237 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/powernv/pmem/ocxl.c b/arch/powerpc/platforms/powernv/pmem/ocxl.c
> index 009d4fd29e7d..e46696d3cc36 100644
> --- a/arch/powerpc/platforms/powernv/pmem/ocxl.c
> +++ b/arch/powerpc/platforms/powernv/pmem/ocxl.c
> @@ -10,6 +10,7 @@
>   #include <misc/ocxl.h>
>   #include <linux/delay.h>
>   #include <linux/ndctl.h>
> +#include <linux/eventfd.h>
>   #include <linux/fs.h>
>   #include <linux/mm_types.h>
>   #include <linux/memory_hotplug.h>
> @@ -335,11 +336,22 @@ static void free_ocxlpmem(struct ocxlpmem *ocxlpmem)
>   {
>   	int rc;
>   
> +	// Disable doorbells
> +	(void)ocxl_global_mmio_set64(ocxlpmem->ocxl_afu, GLOBAL_MMIO_CHIEC,
> +				     OCXL_LITTLE_ENDIAN,
> +				     GLOBAL_MMIO_CHI_ALL);
> +
>   	if (ocxlpmem->nvdimm_bus)
>   		nvdimm_bus_unregister(ocxlpmem->nvdimm_bus);
>   
>   	free_minor(ocxlpmem);
>   
> +	if (ocxlpmem->irq_addr[1])
> +		iounmap(ocxlpmem->irq_addr[1]);
> +
> +	if (ocxlpmem->irq_addr[0])
> +		iounmap(ocxlpmem->irq_addr[0]);
> +
>   	if (ocxlpmem->cdev.owner)
>   		cdev_del(&ocxlpmem->cdev);
>   
> @@ -443,6 +455,11 @@ static int file_release(struct inode *inode, struct file *file)
>   {
>   	struct ocxlpmem *ocxlpmem = file->private_data;
>   
> +	if (ocxlpmem->ev_ctx) {
> +		eventfd_ctx_put(ocxlpmem->ev_ctx);
> +		ocxlpmem->ev_ctx = NULL;
> +	}
> +
>   	ocxlpmem_put(ocxlpmem);
>   	return 0;
>   }
> @@ -938,6 +955,51 @@ static int ioctl_controller_stats(struct ocxlpmem *ocxlpmem,
>   	return rc;
>   }
>   
> +static int ioctl_eventfd(struct ocxlpmem *ocxlpmem,
> +		 struct ioctl_ocxl_pmem_eventfd __user *uarg)
> +{
> +	struct ioctl_ocxl_pmem_eventfd args;
> +
> +	if (copy_from_user(&args, uarg, sizeof(args)))
> +		return -EFAULT;
> +
> +	if (ocxlpmem->ev_ctx)
> +		return -EINVAL;


EBUSY?


> +
> +	ocxlpmem->ev_ctx = eventfd_ctx_fdget(args.eventfd);
> +	if (!ocxlpmem->ev_ctx)
> +		return -EFAULT;


Why not use what eventfd_ctx_fdget() returned? (through some IS_ERR() 
and PTR_ERR() convolution)


> +
> +	return 0;
> +}
> +
> +static int ioctl_event_check(struct ocxlpmem *ocxlpmem, u64 __user *uarg)
> +{
> +	u64 val = 0;
> +	int rc;
> +	u64 chi = 0;
> +
> +	rc = ocxlpmem_chi(ocxlpmem, &chi);
> +	if (rc < 0)
> +		return rc;
> +
> +	if (chi & GLOBAL_MMIO_CHI_ELA)
> +		val |= IOCTL_OCXL_PMEM_EVENT_ERROR_LOG_AVAILABLE;
> +
> +	if (chi & GLOBAL_MMIO_CHI_CDA)
> +		val |= IOCTL_OCXL_PMEM_EVENT_CONTROLLER_DUMP_AVAILABLE;
> +
> +	if (chi & GLOBAL_MMIO_CHI_CFFS)
> +		val |= IOCTL_OCXL_PMEM_EVENT_FIRMWARE_FATAL;
> +
> +	if (chi & GLOBAL_MMIO_CHI_CHFS)
> +		val |= IOCTL_OCXL_PMEM_EVENT_HARDWARE_FATAL;
> +
> +	rc = copy_to_user((u64 __user *) uarg, &val, sizeof(val));
> +


copy_to_user doesn't return an errno. Should be:

if (copy_to_user((u64 __user *) uarg, &val, sizeof(val)))
	return -EFAULT;


> +	return rc;
> +}
> +
>   static long file_ioctl(struct file *file, unsigned int cmd, unsigned long args)
>   {
>   	struct ocxlpmem *ocxlpmem = file->private_data;
> @@ -966,6 +1028,15 @@ static long file_ioctl(struct file *file, unsigned int cmd, unsigned long args)
>   		rc = ioctl_controller_stats(ocxlpmem,
>   					    (struct ioctl_ocxl_pmem_controller_stats __user *)args);
>   		break;
> +
> +	case IOCTL_OCXL_PMEM_EVENTFD:
> +		rc = ioctl_eventfd(ocxlpmem,
> +				   (struct ioctl_ocxl_pmem_eventfd __user *)args);
> +		break;
> +
> +	case IOCTL_OCXL_PMEM_EVENT_CHECK:
> +		rc = ioctl_event_check(ocxlpmem, (u64 __user *)args);
> +		break;
>   	}
>   
>   	return rc;
> @@ -1107,6 +1178,146 @@ static void dump_error_log(struct ocxlpmem *ocxlpmem)
>   	kfree(buf);
>   }
>   
> +static irqreturn_t imn0_handler(void *private)
> +{
> +	struct ocxlpmem *ocxlpmem = private;
> +	u64 chi = 0;
> +
> +	(void)ocxlpmem_chi(ocxlpmem, &chi);
> +
> +	if (chi & GLOBAL_MMIO_CHI_ELA) {
> +		dev_warn(&ocxlpmem->dev, "Error log is available\n");
> +
> +		if (ocxlpmem->ev_ctx)
> +			eventfd_signal(ocxlpmem->ev_ctx, 1);
> +	}
> +
> +	if (chi & GLOBAL_MMIO_CHI_CDA) {
> +		dev_warn(&ocxlpmem->dev, "Controller dump is available\n");
> +
> +		if (ocxlpmem->ev_ctx)
> +			eventfd_signal(ocxlpmem->ev_ctx, 1);
> +	}
> +
> +


(at least) one empty line too many.


> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t imn1_handler(void *private)
> +{
> +	struct ocxlpmem *ocxlpmem = private;
> +	u64 chi = 0;
> +
> +	(void)ocxlpmem_chi(ocxlpmem, &chi);
> +
> +	if (chi & (GLOBAL_MMIO_CHI_CFFS | GLOBAL_MMIO_CHI_CHFS)) {
> +		dev_err(&ocxlpmem->dev,
> +			"Controller status is fatal, chi=0x%llx, going offline\n", chi);
> +
> +		if (ocxlpmem->nvdimm_bus) {
> +			nvdimm_bus_unregister(ocxlpmem->nvdimm_bus);
> +			ocxlpmem->nvdimm_bus = NULL;
> +		}
> +
> +		if (ocxlpmem->ev_ctx)
> +			eventfd_signal(ocxlpmem->ev_ctx, 1);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +
> +/**
> + * ocxlpmem_setup_irq() - Set up the IRQs for the OpenCAPI Persistent Memory device
> + * @ocxlpmem: the device metadata
> + * Return: 0 on success, negative on failure
> + */
> +static int ocxlpmem_setup_irq(struct ocxlpmem *ocxlpmem)
> +{
> +	int rc;
> +	u64 irq_addr;
> +
> +	rc = ocxl_afu_irq_alloc(ocxlpmem->ocxl_context, &ocxlpmem->irq_id[0]);
> +	if (rc)
> +		return rc;
> +
> +	rc = ocxl_irq_set_handler(ocxlpmem->ocxl_context, ocxlpmem->irq_id[0],
> +				  imn0_handler, NULL, ocxlpmem);
> +
> +	irq_addr = ocxl_afu_irq_get_addr(ocxlpmem->ocxl_context, ocxlpmem->irq_id[0]);
> +	if (!irq_addr)
> +		return -EINVAL;
> +
> +	ocxlpmem->irq_addr[0] = ioremap(irq_addr, PAGE_SIZE);
> +	if (!ocxlpmem->irq_addr[0])
> +		return -EINVAL;
> +
> +	rc = ocxl_global_mmio_write64(ocxlpmem->ocxl_afu, GLOBAL_MMIO_IMA0_OHP,
> +				      OCXL_LITTLE_ENDIAN,
> +				      (u64)ocxlpmem->irq_addr[0]);
> +	if (rc)
> +		goto out_irq0;
> +
> +	rc = ocxl_global_mmio_write64(ocxlpmem->ocxl_afu, GLOBAL_MMIO_IMA0_CFP,
> +				      OCXL_LITTLE_ENDIAN, 0);
> +	if (rc)
> +		goto out_irq0;


That's a few lines of duplicate code. On the other hand, there's enough 
varying parameters between the 2 interrupts that factorizing in a 
subfunction would be slightly less readable. So duplicating is probably ok.


> +	rc = ocxl_afu_irq_alloc(ocxlpmem->ocxl_context, &ocxlpmem->irq_id[1]);
> +	if (rc)
> +		goto out_irq0;
> +
> +
> +	rc = ocxl_irq_set_handler(ocxlpmem->ocxl_context, ocxlpmem->irq_id[1],
> +				  imn1_handler, NULL, ocxlpmem);
> +	if (rc)
> +		goto out_irq0;
> +
> +	irq_addr = ocxl_afu_irq_get_addr(ocxlpmem->ocxl_context, ocxlpmem->irq_id[1]);
> +	if (!irq_addr) {
> +		rc = -EFAULT;
> +		goto out_irq0;
> +	}
> +
> +	ocxlpmem->irq_addr[1] = ioremap(irq_addr, PAGE_SIZE);
> +	if (!ocxlpmem->irq_addr[1]) {
> +		rc = -EINVAL;
> +		goto out_irq0;
> +	}
> +
> +	rc = ocxl_global_mmio_write64(ocxlpmem->ocxl_afu, GLOBAL_MMIO_IMA1_OHP,
> +				      OCXL_LITTLE_ENDIAN,
> +				      (u64)ocxlpmem->irq_addr[1]);
> +	if (rc)
> +		goto out_irq1;
> +
> +	rc = ocxl_global_mmio_write64(ocxlpmem->ocxl_afu, GLOBAL_MMIO_IMA1_CFP,
> +				      OCXL_LITTLE_ENDIAN, 0);
> +	if (rc)
> +		goto out_irq1;
> +
> +	// Enable doorbells
> +	rc = ocxl_global_mmio_set64(ocxlpmem->ocxl_afu, GLOBAL_MMIO_CHIE,
> +				    OCXL_LITTLE_ENDIAN,
> +				    GLOBAL_MMIO_CHI_ELA | GLOBAL_MMIO_CHI_CDA |
> +				    GLOBAL_MMIO_CHI_CFFS | GLOBAL_MMIO_CHI_CHFS |
> +				    GLOBAL_MMIO_CHI_NSCRA);


GLOBAL_MMIO_CHI_NSCRA doesn't seem to be handled in the handlers.


> +	if (rc)
> +		goto out_irq1;
> +
> +	return 0;
> +
> +out_irq1:
> +	iounmap(ocxlpmem->irq_addr[1]);
> +	ocxlpmem->irq_addr[1] = NULL;
> +
> +out_irq0:
> +	iounmap(ocxlpmem->irq_addr[0]);
> +	ocxlpmem->irq_addr[0] = NULL;
> +
> +	return rc;
> +}
> +
>   /**
>    * probe_function0() - Set up function 0 for an OpenCAPI persistent memory device
>    * This is important as it enables templates higher than 0 across all other functions,
> @@ -1216,6 +1427,11 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>   		goto err;
>   	}
>   
> +	if (ocxlpmem_setup_irq(ocxlpmem)) {
> +		dev_err(&pdev->dev, "Could not set up OCXL IRQs\n");


Like with other patches, rc needs to be set.


> +		goto err;
> +	}
> +
>   	if (setup_command_metadata(ocxlpmem)) {
>   		dev_err(&pdev->dev, "Could not read OCXL command matada\n");
>   		goto err;
> diff --git a/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> index b953ee522ed4..927690f4888f 100644
> --- a/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> +++ b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> @@ -103,6 +103,10 @@ struct ocxlpmem {
>   	struct pci_dev *pdev;
>   	struct cdev cdev;
>   	struct ocxl_fn *ocxl_fn;
> +#define SCM_IRQ_COUNT 2
> +	int irq_id[SCM_IRQ_COUNT];
> +	struct dev_pagemap irq_pgmap[SCM_IRQ_COUNT];


irq_pgmap is not used.


> +	void *irq_addr[SCM_IRQ_COUNT];
>   	struct nd_interleave_set nd_set;
>   	struct nvdimm_bus_descriptor bus_desc;
>   	struct nvdimm_bus *nvdimm_bus;
> @@ -113,6 +117,7 @@ struct ocxlpmem {
>   	struct command_metadata ns_command;
>   	struct resource pmem_res;
>   	struct nd_region *nd_region;
> +	struct eventfd_ctx *ev_ctx;
>   	char fw_version[8+1];
>   	u32 timeouts[ADMIN_COMMAND_MAX+1];
>   
> diff --git a/include/uapi/nvdimm/ocxl-pmem.h b/include/uapi/nvdimm/ocxl-pmem.h
> index add223aa2fdb..988eb0bc413d 100644
> --- a/include/uapi/nvdimm/ocxl-pmem.h
> +++ b/include/uapi/nvdimm/ocxl-pmem.h
> @@ -66,6 +66,20 @@ struct ioctl_ocxl_pmem_controller_stats {
>   	__u64 cache_write_latency; /* nanoseconds */
>   };
>   
> +struct ioctl_ocxl_pmem_eventfd {
> +	__s32 eventfd;
> +	__u32 reserved;
> +};
> +
> +#ifndef BIT_ULL
> +#define BIT_ULL(nr)	(1ULL << (nr))
> +#endif
> +
> +#define IOCTL_OCXL_PMEM_EVENT_CONTROLLER_DUMP_AVAILABLE	BIT_ULL(0)
> +#define IOCTL_OCXL_PMEM_EVENT_ERROR_LOG_AVAILABLE	BIT_ULL(1)
> +#define IOCTL_OCXL_PMEM_EVENT_HARDWARE_FATAL		BIT_ULL(2)
> +#define IOCTL_OCXL_PMEM_EVENT_FIRMWARE_FATAL		BIT_ULL(3)
> +


I'm not fond of adding a macro with such a generic name as BIT_ULL() in 
a user header file. What's wrong with:

#define IOCTL_OCXL_PMEM_EVENT_CONTROLLER_DUMP_AVAILABLE	0x1
#define IOCTL_OCXL_PMEM_EVENT_ERROR_LOG_AVAILABLE	0x2
#define IOCTL_OCXL_PMEM_EVENT_HARDWARE_FATAL		0x4
#define IOCTL_OCXL_PMEM_EVENT_FIRMWARE_FATAL		0x8


   Fred


>   /* ioctl numbers */
>   #define OCXL_PMEM_MAGIC 0x5C
>   /* SCM devices */
> @@ -74,5 +88,7 @@ struct ioctl_ocxl_pmem_controller_stats {
>   #define IOCTL_OCXL_PMEM_CONTROLLER_DUMP_DATA		_IOWR(OCXL_PMEM_MAGIC, 0x03, struct ioctl_ocxl_pmem_controller_dump_data)
>   #define IOCTL_OCXL_PMEM_CONTROLLER_DUMP_COMPLETE	_IO(OCXL_PMEM_MAGIC, 0x04)
>   #define IOCTL_OCXL_PMEM_CONTROLLER_STATS		_IO(OCXL_PMEM_MAGIC, 0x05)
> +#define IOCTL_OCXL_PMEM_EVENTFD				_IOW(OCXL_PMEM_MAGIC, 0x06, struct ioctl_ocxl_pmem_eventfd)
> +#define IOCTL_OCXL_PMEM_EVENT_CHECK			_IOR(OCXL_PMEM_MAGIC, 0x07, __u64)
>   
>   #endif /* _UAPI_OCXL_SCM_H */
>