Commit 2a35703a authored by Niklas Cassel's avatar Niklas Cassel Committed by Bjorn Helgaas
Browse files

misc: pci_endpoint_test: Use memcpy_toio()/memcpy_fromio() for BAR tests 

The current code uses writel()/readl(), which has an implicit memory
barrier for every single readl()/writel().

Additionally, reading 4 bytes at a time over the PCI bus is not really
optimal, considering that this code is running in an ioctl handler.

Use memcpy_toio()/memcpy_fromio() for BAR tests.

Before patch with a 4MB BAR:

  $ time /usr/bin/pcitest -b 1
  BAR1:           OKAY
  real    0m 1.56s

After patch with a 4MB BAR:

  $ time /usr/bin/pcitest -b 1
  BAR1:           OKAY
  real    0m 0.54s

Link: https://lore.kernel.org/linux-pci/20240322164139.678228-1-cassel@kernel.org


Signed-off-by: default avatarNiklas Cassel <cassel@kernel.org>
Signed-off-by: default avatarKrzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
parent 199b03db

drivers/misc/pci_endpoint_test.c

+42 −12
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
 */



#include <linux/crc32.h>

#include <linux/cleanup.h>

#include <linux/delay.h>

#include <linux/fs.h>

#include <linux/io.h>
@@ -275,31 +276,60 @@ static const u32 bar_test_pattern[] = { 
	0xA5A5A5A5,

};



static int pci_endpoint_test_bar_memcmp(struct pci_endpoint_test *test,

					enum pci_barno barno, int offset,

					void *write_buf, void *read_buf,

					int size)

{

	memset(write_buf, bar_test_pattern[barno], size);

	memcpy_toio(test->bar[barno] + offset, write_buf, size);



	memcpy_fromio(read_buf, test->bar[barno] + offset, size);



	return memcmp(write_buf, read_buf, size);

}



static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,

				  enum pci_barno barno)

{

	int j;

	u32 val;

	int size;

	int j, bar_size, buf_size, iters, remain;

	void *write_buf __free(kfree) = NULL;

	void *read_buf __free(kfree) = NULL;

	struct pci_dev *pdev = test->pdev;



	if (!test->bar[barno])

		return false;



	size = pci_resource_len(pdev, barno);

	bar_size = pci_resource_len(pdev, barno);



	if (barno == test->test_reg_bar)

		size = 0x4;

		bar_size = 0x4;



	for (j = 0; j < size; j += 4)

		pci_endpoint_test_bar_writel(test, barno, j,

					     bar_test_pattern[barno]);

	/*

	 * Allocate a buffer of max size 1MB, and reuse that buffer while

	 * iterating over the whole BAR size (which might be much larger).

	 */

	buf_size = min(SZ_1M, bar_size);



	for (j = 0; j < size; j += 4) {

		val = pci_endpoint_test_bar_readl(test, barno, j);

		if (val != bar_test_pattern[barno])

	write_buf = kmalloc(buf_size, GFP_KERNEL);

	if (!write_buf)

		return false;



	read_buf = kmalloc(buf_size, GFP_KERNEL);

	if (!read_buf)

		return false;



	iters = bar_size / buf_size;

	for (j = 0; j < iters; j++)

		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * j,

						 write_buf, read_buf, buf_size))

			return false;



	remain = bar_size % buf_size;

	if (remain)

		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * iters,

						 write_buf, read_buf, remain))

			return false;

	}



	return true;

}