Re: [PATCH v3 1/1] PCI: Add KUnit tests for __pci_read_base()

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Nov 18, 2021 at 10:48:51PM +0530, Naveen Naidu wrote:
> Currently it is hard to debug issues in the resource assignment code due
> to long reporduction cycles between the developer trying to fix the code
> and the user testing it due to the lack of hardware device with the
> developer [1].
> 
> [1]:
> https://lore.kernel.org/all/20210621123714.GA3286648@bjorn-Precision-5520/
> 
> This adds KUnit tests for __pci_read_base() which is only  dependent
> on software structures, so no hardware is needed to run these.
> 
> This lays the foundation for test fixtures we can use to reproduce the
> resource assignment code path of PCI.
> 
> Sample output from KUnit Test run:
> 
>       # Subtest: __pci_read_base()
>       1..3
>       # test_pci_read_base_type_0_hdr_approach_1: initializing __pci_read_base() tests
>    (null): reg 0x18: [mem 0x4f400000-0x4f400fff]
>       ok 1 - test_pci_read_base_type_0_hdr_approach_1
>       # test_pci_read_base_type_0_hdr_approach_2: initializing __pci_read_base() tests
>    (null): reg 0x18: [mem 0x4f400000-0x4f400fff]
>    (null): reg 0x1c: [mem 0xaf400000-0xaf4000ff]
>       ok 2 - test_pci_read_base_type_0_hdr_approach_2
>       # test_pci_read_base_type_1_hdr: initializing __pci_read_base() tests
>    (null): reg 0x10: [mem 0xaf400000-0xaf4000ff]
>       ok 3 - test_pci_read_base_type_1_hdr
>   # __pci_read_base(): pass:3 fail:0 skip:0 total:3
>   # Totals: pass:3 fail:0 skip:0 total:3
>   # ok 8 - __pci_read_base()
> 
> Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
> ---
>  drivers/pci/Kconfig              |   4 +
>  drivers/pci/Makefile             |   3 +
>  drivers/pci/pci-read-base-test.c | 803 +++++++++++++++++++++++++++++++
>  3 files changed, 810 insertions(+)
>  create mode 100644 drivers/pci/pci-read-base-test.c
> 
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index 43e615aa12ff..12b3779fb640 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -252,6 +252,10 @@ config PCIE_BUS_PEER2PEER
>  
>  endchoice
>  
> +config PCI_READ_BASE_KUNIT_TEST
> +	tristate "KUnit tests for __pci_read_base() in probe.c"
> +	depends on PCI && KUNIT=y
> +
>  source "drivers/pci/hotplug/Kconfig"
>  source "drivers/pci/controller/Kconfig"
>  source "drivers/pci/endpoint/Kconfig"
> diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
> index d62c4ac4ae1b..010a903c3d5d 100644
> --- a/drivers/pci/Makefile
> +++ b/drivers/pci/Makefile
> @@ -36,4 +36,7 @@ obj-$(CONFIG_PCI_ENDPOINT)	+= endpoint/
>  obj-y				+= controller/
>  obj-y				+= switch/
>  
> +# KUnit test files
> +obj-$(CONFIG_PCI_READ_BASE_KUNIT_TEST) += pci-read-base-test.o
> +
>  subdir-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG
> diff --git a/drivers/pci/pci-read-base-test.c b/drivers/pci/pci-read-base-test.c
> new file mode 100644
> index 000000000000..df89d50b0321
> --- /dev/null
> +++ b/drivers/pci/pci-read-base-test.c
> @@ -0,0 +1,803 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KUnit tests for __pci_read_base()
> + *
> + * Author: Naveen Naidu <naveennaidu479@gmail.com>
> + */
> +#include <kunit/test.h>
> +#include <linux/pci.h>
> +#include <linux/math.h>
> +#include <linux/errno.h>
> +
> +#include "pci.h"
> +
> +#define MY_PCI_BUS_NUM 0x011
> +#define NUM_32_BITCONFIG_REGISTERS 16
> +
> +/*
> + * Representation of type 0/1 headers.
> + *
> + * Each element of the array represents one 32 bit register of the
> + * Type 0/1 Header register.
> + */
> +u32 config_registers[NUM_32_BITCONFIG_REGISTERS];

static?

> +
> +/* Type of the device you are testing */
> +unsigned int type_header_test_case;

static?


> +
> +/* Type 0/1 Header register values */
> +struct config_space_bitfield {
> +	char name[64];
> +	unsigned int offset;
> +	unsigned int size; /* In bytes */
> +	unsigned int bit_array_index;
> +	unsigned int value;
> +};
> +
> +/*
> + * The index value of BARS in the type_0/1_header struct.
> + * Useful for setting the values for test cases.
> + */
> +enum type_header_BAR_index {
> +	BAR0 = 3,
> +	BAR1,
> +	BAR2,
> +	BAR3,
> +	BAR4,
> +	BAR5
> +};
> +
> +/* PCI Type 0 Header for Endpoints */
> +static struct config_space_bitfield type_0_header[] = {
> +	{"Vendor ID",	PCI_VENDOR_ID,		2,	0,	0},
> +	{"Device ID",	PCI_DEVICE_ID,		2,	16,	0},
> +	{"Command",	PCI_COMMAND,		2,	32,	0},
> +	{"BAR 0",	PCI_BASE_ADDRESS_0,	4,	128,	0},
> +	{"BAR 1",	PCI_BASE_ADDRESS_1,	4,	160,	0},
> +	{"BAR 2",	PCI_BASE_ADDRESS_2,	4,	192,	0},
> +	{"BAR 3",	PCI_BASE_ADDRESS_3,	4,	224,	0},
> +	{"BAR 4",	PCI_BASE_ADDRESS_4,	4,	256,	0},
> +	{"BAR 5",	PCI_BASE_ADDRESS_5,	4,	288,	0}
> +};
> +
> +/* PCI Type 1 Header for Bridges */
> +static struct config_space_bitfield type_1_header[] = {
> +	{"Vendor ID",	PCI_VENDOR_ID,		2,	0,	0},
> +	{"Device ID",	PCI_DEVICE_ID,		2,	16,	0},
> +	{"Command",	PCI_COMMAND,		2,	32,	0},
> +	{"BAR 0",	PCI_BASE_ADDRESS_0,	4,	128,	0},
> +	{"BAR 1",	PCI_BASE_ADDRESS_1,	4,	160,	0}
> +};
> +
> +/*
> + * -----------------------------------------------------------------------
> + * Data structures to hold test cases values
> + * -----------------------------------------------------------------------
> + */
> +
> +/* Used for setting the test values of BAR registers. */
> +struct config_BARS {
> +	char name[64];
> +	unsigned int offset;

u32?

> +	/*
> +	 * Allocated Address size.
> +	 *
> +	 * Value to return, when all 1's are written to BAR registers.
> +	 *
> +	 * See (NOTE: How to calculate the allocated address size for the BAR
> +	 * registers) comment below.
> +	 */
> +	unsigned int allocated_size;

u32?
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