Re: [PATCH v11 3/4] cxl/core, EINJ: Add EINJ CXL debugfs files and EINJ helper functions

[Dan Williams <dan.j.williams@intel.com>]

Dan Williams wrote:
> Ben Cheatham wrote:
> > 
> > 
> > On 2/8/24 2:00 PM, Ben Cheatham wrote:
> > > Implement CXL helper functions in the EINJ module for getting/injecting
> > > available CXL protocol error types and export them to sysfs under
> > > kernel/debug/cxl.
> > > 
> > > The kernel/debug/cxl/einj_types file will print the available CXL
> > > protocol errors in the same format as the available_error_types
> > > file provided by the EINJ module. The
> > > kernel/debug/cxl/$dport_dev/einj_inject is functionally the same as the
> > > error_type and error_inject files provided by the EINJ module, i.e.:
> > > writing an error type into $dport_dev/einj_inject will inject said error
> > > type into the CXL dport represented by $dport_dev.
> > > 
> > > Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> > > Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
> > > ---
> > >  Documentation/ABI/testing/debugfs-cxl |  22 ++++
> > >  MAINTAINERS                           |   1 +
> > >  drivers/acpi/apei/einj.c              | 158 ++++++++++++++++++++++++--
> > >  drivers/cxl/core/port.c               |  39 +++++++
> > >  include/linux/einj-cxl.h              |  45 ++++++++
> > >  5 files changed, 255 insertions(+), 10 deletions(-)
> > >  create mode 100644 include/linux/einj-cxl.h
> > > 
> > > diff --git a/Documentation/ABI/testing/debugfs-cxl b/Documentation/ABI/testing/debugfs-cxl
> > > index fe61d372e3fa..bcd985cca66a 100644
> > > --- a/Documentation/ABI/testing/debugfs-cxl
> > > +++ b/Documentation/ABI/testing/debugfs-cxl
> > > @@ -33,3 +33,25 @@ Description:
> > >  		device cannot clear poison from the address, -ENXIO is returned.
> > >  		The clear_poison attribute is only visible for devices
> > >  		supporting the capability.
> > > +
> > > +What:		/sys/kernel/debug/cxl/einj_types
> > > +Date:		January, 2024
> > > +KernelVersion:	v6.9
> > > +Contact:	linux-cxl@vger.kernel.org
> > > +Description:
> > > +		(RO) Prints the CXL protocol error types made available by
> > > +		the platform in the format "0x<error number>	<error type>".
> > > +		The <error number> can be written to einj_inject to inject
> > > +		<error type> into a chosen dport.
> > > +
> > > +What:		/sys/kernel/debug/cxl/$dport_dev/einj_inject
> > > +Date:		January, 2024
> > > +KernelVersion:	v6.9
> > > +Contact:	linux-cxl@vger.kernel.org
> > > +Description:
> > > +		(WO) Writing an integer to this file injects the corresponding
> > > +		CXL protocol error into $dport_dev ($dport_dev will be a device
> > > +		name from /sys/bus/pci/devices). The integer to type mapping for
> > > +		injection can be found by reading from einj_types. If the dport
> > > +		was enumerated in RCH mode, a CXL 1.1 error is injected, otherwise
> > > +		a CXL 2.0 error is injected.
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 9104430e148e..02d7feb2ed1f 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -5246,6 +5246,7 @@ L:	linux-cxl@vger.kernel.org
> > >  S:	Maintained
> > >  F:	drivers/cxl/
> > >  F:	include/uapi/linux/cxl_mem.h
> > > +F:  include/linux/einj-cxl.h
> > >  F:	tools/testing/cxl/
> > >  
> > >  COMPUTE EXPRESS LINK PMU (CPMU)
> > > diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
> > > index 73dde21d3e89..9137cc01f791 100644
> > > --- a/drivers/acpi/apei/einj.c
> > > +++ b/drivers/acpi/apei/einj.c
> > > @@ -21,6 +21,7 @@
> > >  #include <linux/nmi.h>
> > >  #include <linux/delay.h>
> > >  #include <linux/mm.h>
> > > +#include <linux/einj-cxl.h>
> > >  #include <linux/platform_device.h>
> > >  #include <asm/unaligned.h>
> > >  
> > > @@ -37,6 +38,20 @@
> > >  #define MEM_ERROR_MASK		(ACPI_EINJ_MEMORY_CORRECTABLE | \
> > >  				ACPI_EINJ_MEMORY_UNCORRECTABLE | \
> > >  				ACPI_EINJ_MEMORY_FATAL)
> > > +#ifndef ACPI_EINJ_CXL_CACHE_CORRECTABLE
> > > +#define ACPI_EINJ_CXL_CACHE_CORRECTABLE     BIT(12)
> > > +#define ACPI_EINJ_CXL_CACHE_UNCORRECTABLE   BIT(13)
> > > +#define ACPI_EINJ_CXL_CACHE_FATAL           BIT(14)
> > > +#define ACPI_EINJ_CXL_MEM_CORRECTABLE       BIT(15)
> > > +#define ACPI_EINJ_CXL_MEM_UNCORRECTABLE     BIT(16)
> > > +#define ACPI_EINJ_CXL_MEM_FATAL             BIT(17)
> > > +#endif
> > > +#define CXL_ERROR_MASK		(ACPI_EINJ_CXL_CACHE_CORRECTABLE | \
> > > +				ACPI_EINJ_CXL_CACHE_UNCORRECTABLE | \
> > > +				ACPI_EINJ_CXL_CACHE_FATAL | \
> > > +				ACPI_EINJ_CXL_MEM_CORRECTABLE | \
> > > +				ACPI_EINJ_CXL_MEM_UNCORRECTABLE | \
> > > +				ACPI_EINJ_CXL_MEM_FATAL)
> > >  
> > >  /*
> > >   * ACPI version 5 provides a SET_ERROR_TYPE_WITH_ADDRESS action.
> > > @@ -543,8 +558,11 @@ static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
> > >  	if (type & ACPI5_VENDOR_BIT) {
> > >  		if (vendor_flags != SETWA_FLAGS_MEM)
> > >  			goto inject;
> > > -	} else if (!(type & MEM_ERROR_MASK) && !(flags & SETWA_FLAGS_MEM))
> > > +	} else if (!(type & MEM_ERROR_MASK) && !(flags & SETWA_FLAGS_MEM)) {
> > >  		goto inject;
> > > +	} else if ((type & CXL_ERROR_MASK) && (flags & SETWA_FLAGS_MEM)) {
> > > +		goto inject;
> > > +	}
> > >  
> > >  	/*
> > >  	 * Disallow crazy address masks that give BIOS leeway to pick
> > > @@ -596,6 +614,9 @@ static const char * const einj_error_type_string[] = {
> > >  	"0x00000200\tPlatform Correctable\n",
> > >  	"0x00000400\tPlatform Uncorrectable non-fatal\n",
> > >  	"0x00000800\tPlatform Uncorrectable fatal\n",
> > > +};
> > > +
> > > +static const char * const einj_cxl_error_type_string[] = {
> > >  	"0x00001000\tCXL.cache Protocol Correctable\n",
> > >  	"0x00002000\tCXL.cache Protocol Uncorrectable non-fatal\n",
> > >  	"0x00004000\tCXL.cache Protocol Uncorrectable fatal\n",
> > > @@ -621,29 +642,44 @@ static int available_error_type_show(struct seq_file *m, void *v)
> > >  
> > >  DEFINE_SHOW_ATTRIBUTE(available_error_type);
> > >  
> > > -static int error_type_get(void *data, u64 *val)
> > > +int einj_cxl_available_error_type_show(struct seq_file *m, void *v)
> > >  {
> > > -	*val = error_type;
> > > +	int cxl_err, rc;
> > > +	u32 available_error_type = 0;
> > > +
> > > +	if (!einj_initialized)
> > > +		return -ENXIO;
> > > +
> > > +	rc = einj_get_available_error_type(&available_error_type);
> > > +	if (rc)
> > > +		return rc;
> > > +
> > > +	for (int pos = 0; pos < ARRAY_SIZE(einj_cxl_error_type_string); pos++) {
> > > +		cxl_err = ACPI_EINJ_CXL_CACHE_CORRECTABLE << pos;
> > > +
> > > +		if (available_error_type & cxl_err)
> > > +			seq_puts(m, einj_cxl_error_type_string[pos]);
> > > +	}
> > >  
> > >  	return 0;
> > >  }
> > > +EXPORT_SYMBOL_NS_GPL(einj_cxl_available_error_type_show, CXL);
> > >  
> > > -static int error_type_set(void *data, u64 val)
> > > +static int validate_error_type(u64 type)
> > >  {
> > > +	u32 tval, vendor, available_error_type = 0;
> > >  	int rc;
> > > -	u32 available_error_type = 0;
> > > -	u32 tval, vendor;
> > >  
> > >  	/* Only low 32 bits for error type are valid */
> > > -	if (val & GENMASK_ULL(63, 32))
> > > +	if (type & GENMASK_ULL(63, 32))
> > >  		return -EINVAL;
> > >  
> > >  	/*
> > >  	 * Vendor defined types have 0x80000000 bit set, and
> > >  	 * are not enumerated by ACPI_EINJ_GET_ERROR_TYPE
> > >  	 */
> > > -	vendor = val & ACPI5_VENDOR_BIT;
> > > -	tval = val & 0x7fffffff;
> > > +	vendor = type & ACPI5_VENDOR_BIT;
> > > +	tval = type & 0x7fffffff;
> > >  
> > >  	/* Only one error type can be specified */
> > >  	if (tval & (tval - 1))
> > > @@ -652,9 +688,105 @@ static int error_type_set(void *data, u64 val)
> > >  		rc = einj_get_available_error_type(&available_error_type);
> > >  		if (rc)
> > >  			return rc;
> > > -		if (!(val & available_error_type))
> > > +		if (!(type & available_error_type))
> > >  			return -EINVAL;
> > >  	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int cxl_dport_get_sbdf(struct pci_dev *dport_dev, u64 *sbdf)
> > > +{
> > > +	struct pci_bus *pbus;
> > > +	struct pci_host_bridge *bridge;
> > > +	u64 seg = 0, bus;
> > > +
> > > +	pbus = dport_dev->bus;
> > > +	bridge = pci_find_host_bridge(pbus);
> > > +
> > > +	if (!bridge)
> > > +		return -ENODEV;
> > > +
> > > +	if (bridge->domain_nr != PCI_DOMAIN_NR_NOT_SET)
> > > +		seg = bridge->domain_nr << 24;
> > > +
> > > +	bus = pbus->number << 16;
> > > +	*sbdf = seg | bus | dport_dev->devfn;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +int einj_cxl_inject_rch_error(u64 rcrb, u64 type)
> > > +{
> > > +	u64 param1 = 0, param2 = 0, param4 = 0;
> > > +	u32 flags;
> > > +	int rc;
> > > +
> > > +	if (!einj_initialized)
> > > +		return -ENXIO;
> > > +
> > > +	/* Only CXL error types can be specified */
> > > +	if (type & ~CXL_ERROR_MASK || (type & ACPI5_VENDOR_BIT))
> > > +		return -EINVAL;
> > > +
> > > +	rc = validate_error_type(type);
> > > +	if (rc)
> > > +		return rc;
> > > +
> > > +	param1 = (u64) rcrb;
> > > +	param2 = 0xfffffffffffff000;
> > > +	flags = 0x2;
> > > +
> > > +	return einj_error_inject(type, flags, param1, param2, 0, param4);
> > > +}
> > > +EXPORT_SYMBOL_NS_GPL(einj_cxl_inject_rch_error, CXL);
> > > +
> > > +int einj_cxl_inject_error(struct pci_dev *dport, u64 type)
> > > +{
> > > +	u64 param1 = 0, param2 = 0, param4 = 0;
> > > +	u32 flags;
> > > +	int rc;
> > > +
> > > +	if (!einj_initialized)
> > > +		return -ENXIO;
> > > +
> > > +	/* Only CXL error types can be specified */
> > > +	if (type & ~CXL_ERROR_MASK || (type & ACPI5_VENDOR_BIT))
> > > +		return -EINVAL;
> > > +
> > > +	rc = validate_error_type(type);
> > > +	if (rc)
> > > +		return rc;
> > > +
> > > +	rc = cxl_dport_get_sbdf(dport, &param4);
> > > +	if (rc)
> > > +		return rc;
> > > +
> > > +	flags = 0x4;
> > > +
> > > +	return einj_error_inject(type, flags, param1, param2, 0, param4);
> > > +}
> > > +EXPORT_SYMBOL_NS_GPL(einj_cxl_inject_error, CXL);
> > > +
> > > +static int error_type_get(void *data, u64 *val)
> > > +{
> > > +	*val = error_type;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int error_type_set(void *data, u64 val)
> > > +{
> > > +	int rc;
> > > +
> > > +	/* CXL error types have to be injected from cxl debugfs */
> > > +	if (val & CXL_ERROR_MASK && !(val & ACPI5_VENDOR_BIT))
> > > +		return -EINVAL;
> > > +
> > > +	rc = validate_error_type(val);
> > > +	if (rc)
> > > +		return rc;
> > > +
> > >  	error_type = val;
> > >  
> > >  	return 0;
> > > @@ -690,6 +822,12 @@ static int einj_check_table(struct acpi_table_einj *einj_tab)
> > >  	return 0;
> > >  }
> > >  
> > > +bool einj_is_initialized(void)
> > > +{
> > > +	return einj_initialized;
> > > +}
> > > +EXPORT_SYMBOL_GPL(einj_is_initialized);
> > > +
> > >  static int __init einj_probe(struct platform_device *pdev)
> > >  {
> > >  	int rc;
> > > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> > > index 8c00fd6be730..c52c92222be5 100644
> > > --- a/drivers/cxl/core/port.c
> > > +++ b/drivers/cxl/core/port.c
> > > @@ -3,6 +3,7 @@
> > >  #include <linux/platform_device.h>
> > >  #include <linux/memregion.h>
> > >  #include <linux/workqueue.h>
> > > +#include <linux/einj-cxl.h>
> > >  #include <linux/debugfs.h>
> > >  #include <linux/device.h>
> > >  #include <linux/module.h>
> > > @@ -797,6 +798,37 @@ static int cxl_dport_setup_regs(struct device *host, struct cxl_dport *dport,
> > >  	return rc;
> > >  }
> > >  
> > > +DEFINE_SHOW_ATTRIBUTE(einj_cxl_available_error_type);
> > > +
> > > +static int cxl_einj_inject(void *data, u64 type)
> > > +{
> > > +	struct cxl_dport *dport = data;
> > > +
> > > +	if (dport->rch)
> > > +		return einj_cxl_inject_rch_error(dport->rcrb.base, type);
> > > +
> > > +	return einj_cxl_inject_error(to_pci_dev(dport->dport_dev), type);
> > > +}
> > > +DEFINE_DEBUGFS_ATTRIBUTE(cxl_einj_inject_fops, NULL, cxl_einj_inject, "%llx\n");
> > > +
> > > +static void cxl_debugfs_create_dport_dir(struct cxl_dport *dport)
> > > +{
> > > +	struct dentry *dir;
> > > +
> > > +	/*
> > > +	 * dport_dev needs to be a PCIe port for CXL 2.0+ ports because
> > > +	 * EINJ expects a dport SBDF to be specified for 2.0 error injection.
> > > +	 */
> > > +	if (!einj_is_initialized() ||
> > > +	    (!dport->rch && !dev_is_pci(dport->dport_dev)))
> > > +		return;
> > > +
> > > +	dir = cxl_debugfs_create_dir(dev_name(dport->dport_dev));
> > > +
> > > +	debugfs_create_file("einj_inject", 0200, dir, dport,
> > > +			    &cxl_einj_inject_fops);
> > > +}
> > > +
> > >  static struct cxl_port *__devm_cxl_add_port(struct device *host,
> > >  					    struct device *uport_dev,
> > >  					    resource_size_t component_reg_phys,
> > > @@ -1144,6 +1176,8 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
> > >  	if (dev_is_pci(dport_dev))
> > >  		dport->link_latency = cxl_pci_get_latency(to_pci_dev(dport_dev));
> > >  
> > > +	cxl_debugfs_create_dport_dir(dport);
> > > +
> > >  	return dport;
> > >  }
> > >  
> > > @@ -2220,6 +2254,11 @@ static __init int cxl_core_init(void)
> > >  
> > >  	cxl_debugfs = debugfs_create_dir("cxl", NULL);
> > >  
> > > +	if (einj_is_initialized()) {
> > > +		debugfs_create_file("einj_types", 0400, cxl_debugfs, NULL,
> > > +				    &einj_cxl_available_error_type_fops);
> > > +	}
> > > +
> > >  	cxl_mbox_init();
> > >  
> > >  	rc = cxl_memdev_init();
> > > diff --git a/include/linux/einj-cxl.h b/include/linux/einj-cxl.h
> > > new file mode 100644
> > > index 000000000000..af57cc8580a6
> > > --- /dev/null
> > > +++ b/include/linux/einj-cxl.h
> > > @@ -0,0 +1,45 @@
> > > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > > +/*
> > > + * CXL protocol Error INJection support.
> > > + *
> > > + * Copyright (c) 2023 Advanced Micro Devices, Inc.
> > > + * All Rights Reserved.
> > > + *
> > > + * Author: Ben Cheatham <benjamin.cheatham@amd.com>
> > > + */
> > > +#ifndef CXL_EINJ_H
> > > +#define CXL_EINJ_H
> > > +
> > > +#include <linux/pci.h>
> > > +
> > > +#if IS_ENABLED(CONFIG_ACPI_APEI_EINJ)
> > 
> > I was testing some other work using this kernel and was getting a linker error
> > when I had CXL_BUS set to 'y' and ACPI_APEI_EINJ set to 'm'. I went ahead and
> > solved it by changing the line above to use IS_REACHABLE() instead. The change
> > shouldn't actually affect the functionality of the patch since this is in a build
> > configuration where the CXL driver isn't using the EINJ module since CONFIG_CXL_EINJ
> > is set to n due to Kconfig restraints.
> > 
> > I can submit another version of this series with this fix, but I don't think it
> > makes much sense for a 1 line change, so I've but a diff below with the change
> > for whoever ends up putting this in their tree:
> 
> I don't think this is the right fix. CONFIG_CXL_EINJ should be disabled when
> CONFIG_CXL_BUS is built-in. Looks like the polarity the dependency is
> backwards. The problem with IS_REACHABLE() is it removes the simple
> debug option of "send me your .config" to see why some functionality is
> not turned on.
> 
> Could you test out flipping the dependency from:
> 
>     depends on ACPI_APEI_EINJ >= CXL_BUS
> 
> ...to:
> 
>     depends on ACPI_APEI_EINJ <= CXL_BUS

Wait, no y == 2 and m == 1, so:

depends on ACPI_APEI_EINJ >= CXL_BUS

...is correct, but you need IS_ENABLED(CONFIG_CXL_EINJ), not
IS_REACHABLE to guard those exports.