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Subject: Re: [PATCH v3 20/27] powerpc/powernv/pmem: Forward events to
 userspace
From:   "Alastair D'Silva" <alastair@au1.ibm.com>
To:     Frederic Barrat <fbarrat@linux.ibm.com>
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>,
        =?ISO-8859-1?Q?C=E9dric?= 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
Date:   Wed, 11 Mar 2020 14:32:23 +1100
In-Reply-To: <7ee589c0-2c02-9b8e-95a9-743ce29674ec@linux.ibm.com>
References: <20200221032720.33893-1-alastair@au1.ibm.com>
         <20200221032720.33893-21-alastair@au1.ibm.com>
         <7ee589c0-2c02-9b8e-95a9-743ce29674ec@linux.ibm.com>
Organization: IBM Australia
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On Wed, 2020-03-04 at 12:00 +0100, Frederic Barrat wrote:
> 
> 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?
> 
Ok

> 
> > +
> > +	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)
> 

Ok
> 
> > +
> > +	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;
> 
Ok

> 
> > +	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.
> 

Ok

> 
> > +	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.
> 

This will be moved to the overwrite patch.

> 
> 
> > +	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.
> 
ok

> 
> > +		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.

Ok
> 
> 
> > +	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
> 
> 

Nothing, I'll change it.

>    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(O
> > CXL_PMEM_MAGIC, 0x03, struct ioctl_ocxl_pmem_controller_dump_data)
> >   #define IOCTL_OCXL_PMEM_CONTROLLER_DUMP_COMPLETE	_IO(OCXL_PMEM_M
> > AGIC, 0x04)
> >   #define IOCTL_OCXL_PMEM_CONTROLLER_STATS		_IO(OCXL_PMEM_M
> > AGIC, 0x05)
> > +#define IOCTL_OCXL_PMEM_EVENTFD				_IOW(OC
> > XL_PMEM_MAGIC, 0x06, struct ioctl_ocxl_pmem_eventfd)
> > +#define IOCTL_OCXL_PMEM_EVENT_CHECK			_IOR(OC
> > XL_PMEM_MAGIC, 0x07, __u64)
> >   
> >   #endif /* _UAPI_OCXL_SCM_H */
> > 
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819