Date:   Fri, 28 Feb 2020 10:51:38 +1100
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     Andrew Donnellan <ajd@...ux.ibm.com>
Cc:     "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        "Oliver O'Halloran" <oohall@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh@...nel.org>,
        Anton Blanchard <anton@...abs.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kurz <groug@...d.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 14/27] powerpc/powernv/pmem: Add support for Admin
 commands

On Thu, 2020-02-27 at 19:22 +1100, Andrew Donnellan wrote:
> On 21/2/20 2:27 pm, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@...ilva.org>
> > 
> > This patch requests the metadata required to issue admin commands,
> > as well
> > as some helper functions to construct and check the completion of
> > the
> > commands.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
> > ---
> >   arch/powerpc/platforms/powernv/pmem/ocxl.c    |  65 ++++++++
> >   .../platforms/powernv/pmem/ocxl_internal.c    | 153
> > ++++++++++++++++++
> >   .../platforms/powernv/pmem/ocxl_internal.h    |  61 +++++++
> >   3 files changed, 279 insertions(+)
> > 
> > diff --git a/arch/powerpc/platforms/powernv/pmem/ocxl.c
> > b/arch/powerpc/platforms/powernv/pmem/ocxl.c
> > index 431212c9f0cc..4e782d22605b 100644
> > --- a/arch/powerpc/platforms/powernv/pmem/ocxl.c
> > +++ b/arch/powerpc/platforms/powernv/pmem/ocxl.c
> > @@ -216,6 +216,58 @@ static int register_lpc_mem(struct ocxlpmem
> > *ocxlpmem)
> >   	return 0;
> >   }
> >   
> > +/**
> > + * extract_command_metadata() - Extract command data from MMIO &
> > save it for further use
> > + * @ocxlpmem: the device metadata
> > + * @offset: The base address of the command data structures
> > (address of CREQO)
> > + * @command_metadata: A pointer to the command metadata to
> > populate
> > + * Return: 0 on success, negative on failure
> > + */
> > +static int extract_command_metadata(struct ocxlpmem *ocxlpmem, u32
> > offset,
> > +					struct command_metadata
> > *command_metadata)
> > +{
> > +	int rc;
> > +	u64 tmp;
> > +
> > +	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu, offset,
> > OCXL_LITTLE_ENDIAN,
> > +				     &tmp);
> > +	if (rc)
> > +		return rc;
> > +
> > +	command_metadata->request_offset = tmp >> 32;
> > +	command_metadata->response_offset = tmp & 0xFFFFFFFF;
> > +
> > +	rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu, offset + 8,
> > OCXL_LITTLE_ENDIAN,
> > +				     &tmp);
> > +	if (rc)
> > +		return rc;
> > +
> > +	command_metadata->data_offset = tmp >> 32;
> > +	command_metadata->data_size = tmp & 0xFFFFFFFF;
> > +
> > +	command_metadata->id = 0;
> > +
> > +	return 0;
> > +}
> > +
> > +/**
> > + * setup_command_metadata() - Set up the command metadata
> > + * @ocxlpmem: the device metadata
> > + */
> > +static int setup_command_metadata(struct ocxlpmem *ocxlpmem)
> > +{
> > +	int rc;
> > +
> > +	mutex_init(&ocxlpmem->admin_command.lock);
> > +
> > +	rc = extract_command_metadata(ocxlpmem, GLOBAL_MMIO_ACMA_CREQO,
> > +				      &ocxlpmem->admin_command);
> > +	if (rc)
> > +		return rc;
> > +
> > +	return 0;
> > +}
> > +
> >   /**
> >    * is_usable() - Is a controller usable?
> >    * @ocxlpmem: the device metadata
> > @@ -456,6 +508,14 @@ static int probe(struct pci_dev *pdev, const
> > struct pci_device_id *ent)
> >   	}
> >   	ocxlpmem->pdev = pdev;
> >   
> > +	ocxlpmem->timeouts[ADMIN_COMMAND_ERRLOG] = 2000; // ms
> > +	ocxlpmem->timeouts[ADMIN_COMMAND_HEARTBEAT] = 100; // ms
> > +	ocxlpmem->timeouts[ADMIN_COMMAND_SMART] = 100; // ms
> > +	ocxlpmem->timeouts[ADMIN_COMMAND_CONTROLLER_DUMP] = 1000; // ms
> > +	ocxlpmem->timeouts[ADMIN_COMMAND_CONTROLLER_STATS] = 100; // ms
> > +	ocxlpmem->timeouts[ADMIN_COMMAND_SHUTDOWN] = 1000; // ms
> > +	ocxlpmem->timeouts[ADMIN_COMMAND_FW_UPDATE] = 16000; // ms
> 
> Why are we keeping these timeouts in a per device struct? I can't
> see 
> anywhere where we change these values.
> 

These are overwritten in a later patch, which I've missed! thanks for
pointing this out.

These initial values will be overwritten by card specific timeouts.

> > +
> >   	pci_set_drvdata(pdev, ocxlpmem);
> >   
> >   	ocxlpmem->ocxl_fn = ocxl_function_open(pdev);
> > @@ -501,6 +561,11 @@ static int probe(struct pci_dev *pdev, const
> > struct pci_device_id *ent)
> >   		goto err;
> >   	}
> >   
> > +	if (setup_command_metadata(ocxlpmem)) {
> > +		dev_err(&pdev->dev, "Could not read OCXL command
> > matada\n");
> 
> metadata

Wow, not sure how that happened.

> 
> Also, "OCXL command metadata" is misleading, this is a pmem specific 
> thing, not an OpenCAPI thing, I would prefer just "command metadata".
> 

Ok

> > +		goto err;
> > +	}
> > +
> >   	elapsed = 0;
> >   	timeout = ocxlpmem->readiness_timeout + ocxlpmem-
> > >memory_available_timeout;
> >   	while (!is_usable(ocxlpmem, false)) {
> > diff --git a/arch/powerpc/platforms/powernv/pmem/ocxl_internal.c
> > b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.c
> > index 617ca943b1b8..583f48023025 100644
> > --- a/arch/powerpc/platforms/powernv/pmem/ocxl_internal.c
> > +++ b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.c
> > @@ -17,3 +17,156 @@ int ocxlpmem_chi(const struct ocxlpmem
> > *ocxlpmem, u64 *chi)
> >   
> >   	return 0;
> >   }
> > +
> > +#define COMMAND_REQUEST_SIZE (8 * sizeof(u64))
> > +static int scm_command_request(const struct ocxlpmem *ocxlpmem,
> > +			       struct command_metadata *cmd, u8
> > op_code)
> > +{
> > +	u64 val = op_code;
> > +	int rc;
> > +	u8 i;
> > +
> > +	cmd->op_code = op_code;
> > +	cmd->id++;
> > +
> > +	val |= ((u64)cmd->id) << 16;
> > +
> > +	rc = ocxl_global_mmio_write64(ocxlpmem->ocxl_afu, cmd-
> > >request_offset,
> > +				      OCXL_LITTLE_ENDIAN, val);
> > +	if (rc)
> > +		return rc;
> > +
> > +	for (i = sizeof(u64); i < COMMAND_REQUEST_SIZE; i +=
> > sizeof(u64)) {
> > +		rc = ocxl_global_mmio_write64(ocxlpmem->ocxl_afu,
> > +					      cmd->request_offset + i,
> > +					      OCXL_LITTLE_ENDIAN, 0);
> > +		if (rc)
> > +			return rc;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +int admin_command_request(struct ocxlpmem *ocxlpmem, u8 op_code)
> > +{
> > +	u64 val;
> > +	int rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
> > GLOBAL_MMIO_CHI,
> > +					 OCXL_LITTLE_ENDIAN, &val);
> > +	if (rc)
> > +		return rc;
> 
> Ignoring the value here expected, you're just trying to verify that
> you 
> don't see an error on the read?
> 

This was some vestigial code that should be removed.

> > +
> > +	return scm_command_request(ocxlpmem, &ocxlpmem->admin_command,
> > op_code);
> > +}
> > +
> > +static int command_response(const struct ocxlpmem *ocxlpmem,
> > +			    const struct command_metadata *cmd)
> > +{
> > +	u64 val;
> > +	u16 id;
> > +	u8 status;
> > +	int rc = ocxl_global_mmio_read64(ocxlpmem->ocxl_afu,
> > +					 cmd->response_offset,
> > +					 OCXL_LITTLE_ENDIAN, &val);
> > +	if (rc)
> > +		return rc;
> > +
> > +	status = val & 0xff;
> > +	id = (val >> 16) & 0xffff;
> > +
> > +	if (id != cmd->id) {
> > +		dev_warn(&ocxlpmem->dev,
> > +			 "Expected response for command %d, but
> > received response for command %d instead.\n",
> > +			 cmd->id, id);
> 
> If this happens I imagine something's gone pretty wrong - this
> should 
> probably be a dev_err()? And perhaps we want to make sure we return
> an 
> error code rather than whatever status code we get from the MMIO?
> 

Ok

> > +	}
> > +
> > +	return status;
> > +}
> > +
> > +int admin_response(const struct ocxlpmem *ocxlpmem)
> > +{
> > +	return command_response(ocxlpmem, &ocxlpmem->admin_command);
> > +}
> > +
> > +
> > +int admin_command_execute(const struct ocxlpmem *ocxlpmem)
> > +{
> > +	return ocxl_global_mmio_set64(ocxlpmem->ocxl_afu,
> > GLOBAL_MMIO_HCI,
> > +				      OCXL_LITTLE_ENDIAN,
> > GLOBAL_MMIO_HCI_ACRW);
> > +}
> > +
> > +static bool admin_command_complete(const struct ocxlpmem
> > *ocxlpmem)
> > +{
> > +	u64 val = 0;
> > +
> > +	int rc = ocxlpmem_chi(ocxlpmem, &val);
> > +
> > +	WARN_ON(rc);
> > +
> > +	return (val & GLOBAL_MMIO_CHI_ACRA) != 0;
> > +}
> > +
> > +int admin_command_complete_timeout(const struct ocxlpmem
> > *ocxlpmem,
> > +				   int command)
> > +{
> > +	u32 timeout = ocxlpmem->timeouts[command];
> > +	// 32 is the next power of 2 greater than the 20ms minimum for
> > msleep
> > +#define TIMEOUT_SLEEP_MILLIS 32
> > +	timeout /= TIMEOUT_SLEEP_MILLIS;
> > +	if (!timeout)
> > +		timeout = DEFAULT_TIMEOUT / TIMEOUT_SLEEP_MILLIS;
> > +
> > +	while (timeout-- > 0) {
> > +		if (admin_command_complete(ocxlpmem))
> > +			return 0;
> > +		msleep(TIMEOUT_SLEEP_MILLIS);
> > +	}
> 
> I think the more traditional way to implement timeouts is something
> more 
> like:
> 
>    unsigned long timeout = jiffies + msecs_to_jiffies(<timeout
> period>);
>    do {
>      <check>
>      <sleep>
>    } while (time_before(jiffies, timeout));
> 

ok

> > +
> > +	if (admin_command_complete(ocxlpmem))
> > +		return 0;
> > +
> > +	return -EBUSY;
> > +}
> > +
> > +int admin_response_handled(const struct ocxlpmem *ocxlpmem)
> > +{
> > +	return ocxl_global_mmio_set64(ocxlpmem->ocxl_afu,
> > GLOBAL_MMIO_CHIC,
> > +				      OCXL_LITTLE_ENDIAN,
> > GLOBAL_MMIO_CHI_ACRA);
> > +}
> 
> This looks wrong? My reading of the spec is that you're meant to
> *clear* 
> ACRA upon completion of handing, this looks like it's setting ACRA to
> 1.
> 

Writing a 1 to the CHIC register clears the respective bit in the CHI
register. I'll add a comment.

> > +
> > +void warn_status(const struct ocxlpmem *ocxlpmem, const char
> > *message,
> > +		     u8 status)
> > +{
> > +	const char *text = "Unknown";
> > +
> > +	switch (status) {
> > +	case STATUS_SUCCESS:
> > +		text = "Success";
> > +		break;
> > +
> > +	case STATUS_MEM_UNAVAILABLE:
> > +		text = "Persistent memory unavailable";
> > +		break;
> > +
> > +	case STATUS_BAD_OPCODE:
> > +		text = "Bad opcode";
> > +		break;
> > +
> > +	case STATUS_BAD_REQUEST_PARM:
> > +		text = "Bad request parameter";
> > +		break;
> > +
> > +	case STATUS_BAD_DATA_PARM:
> > +		text = "Bad data parameter";
> > +		break;
> > +
> > +	case STATUS_DEBUG_BLOCKED:
> > +		text = "Debug action blocked";
> > +		break;
> > +
> > +	case STATUS_FAIL:
> > +		text = "Failed";
> > +		break;
> > +	}
> > +
> > +	dev_warn(&ocxlpmem->dev, "%s: %s (%x)\n", message, text,
> > status);
> > +}
> > diff --git a/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> > b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> > index ba0301533d00..2fef68c71271 100644
> > --- a/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> > +++ b/arch/powerpc/platforms/powernv/pmem/ocxl_internal.h
> > @@ -7,6 +7,7 @@
> >   #include <linux/mm.h>
> >   
> >   #define LABEL_AREA_SIZE	(1UL << PA_SECTION_SHIFT)
> > +#define DEFAULT_TIMEOUT 100
> >   
> >   #define GLOBAL_MMIO_CHI		0x000
> >   #define GLOBAL_MMIO_CHIC	0x008
> > @@ -80,6 +81,16 @@
> >   #define STATUS_FW_ARG_INVALID	0x51
> >   #define STATUS_FW_INVALID	0x52
> >   
> > +struct command_metadata {
> > +	u32 request_offset;
> > +	u32 response_offset;
> > +	u32 data_offset;
> > +	u32 data_size;
> > +	struct mutex lock;
> > +	u16 id;
> > +	u8 op_code;
> > +};
> > +
> >   struct ocxlpmem_function0 {
> >   	struct pci_dev *pdev;
> >   	struct ocxl_fn *ocxl_fn;
> > @@ -95,9 +106,11 @@ struct ocxlpmem {
> >   	struct ocxl_afu *ocxl_afu;
> >   	struct ocxl_context *ocxl_context;
> >   	void *metadata_addr;
> > +	struct command_metadata admin_command;
> >   	struct resource pmem_res;
> >   	struct nd_region *nd_region;
> >   	char fw_version[8+1];
> > +	u32 timeouts[ADMIN_COMMAND_MAX+1];
> >   
> >   	u32 max_controller_dump_size;
> >   	u16 scm_revision; // major/minor
> > @@ -122,3 +135,51 @@ struct ocxlpmem {
> >    * Returns 0 on success, negative on error
> >    */
> >   int ocxlpmem_chi(const struct ocxlpmem *ocxlpmem, u64 *chi);
> > +
> > +/**
> > + * admin_command_request() - Issue an admin command request
> > + * @ocxlpmem: the device metadata
> > + * @op_code: The op-code for the command
> > + *
> > + * Returns an identifier for the command, or negative on error
> > + */
> > +int admin_command_request(struct ocxlpmem *ocxlpmem, u8 op_code);
> > +
> > +/**
> > + * admin_response() - Validate an admin response
> > + * @ocxlpmem: the device metadata
> > + * Returns the status code of the command, or negative on error
> > + */
> > +int admin_response(const struct ocxlpmem *ocxlpmem);
> > +
> > +/**
> > + * admin_command_execute() - Notify the controller to start
> > processing a pending admin command
> > + * @ocxlpmem: the device metadata
> > + * Returns 0 on success, negative on error
> > + */
> > +int admin_command_execute(const struct ocxlpmem *ocxlpmem);
> > +
> > +/**
> > + * admin_command_complete_timeout() - Wait for an admin command to
> > finish executing
> > + * @ocxlpmem: the device metadata
> > + * @command: the admin command to wait for completion (determines
> > the timeout)
> > + * Returns 0 on success, -EBUSY on timeout
> > + */
> > +int admin_command_complete_timeout(const struct ocxlpmem
> > *ocxlpmem,
> > +				   int command);
> > +
> > +/**
> > + * admin_response_handled() - Notify the controller that the admin
> > response has been handled
> > + * @ocxlpmem: the device metadata
> > + * Returns 0 on success, negative on failure
> > + */
> > +int admin_response_handled(const struct ocxlpmem *ocxlpmem);
> > +
> > +/**
> > + * warn_status() - Emit a kernel warning showing a command status.
> > + * @ocxlpmem: the device metadata
> > + * @message: A message to accompany the warning
> > + * @status: The command status
> > + */
> > +void warn_status(const struct ocxlpmem *ocxlpmem, const char
> > *message,
> > +		 u8 status);
> > 
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

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