From: Niklas Cassel <cassel@kernel.org>
To: "Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Cc: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Damien Le Moal <dlemoal@kernel.org>,
Niklas Cassel <cassel@kernel.org>,
linux-pci@vger.kernel.org
Subject: [PATCH v4] misc: pci_endpoint_test: Use memcpy_toio()/memcpy_fromio() for BAR tests
Date: Fri, 22 Mar 2024 17:41:38 +0100 [thread overview]
Message-ID: <20240322164139.678228-1-cassel@kernel.org> (raw)
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
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
Changes since v3:
-Use scope-based resource management __free attribute from cleanup.h to
avoid overly verbose gotos and labels for error handling.
-Added a comment related to why we allocate a buffer of max 1MB.
(kmalloc() default upper limit is usually 4 MB on ARM and x86.)
drivers/misc/pci_endpoint_test.c | 54 +++++++++++++++++++++++++-------
1 file changed, 42 insertions(+), 12 deletions(-)
diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 705029ad8eb5..bf64d3aff7d8 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -7,6 +7,7 @@
*/
#include <linux/crc32.h>
+#include <linux/cleanup.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/io.h>
@@ -272,31 +273,60 @@ 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;
}
--
2.44.0
next reply other threads:[~2024-03-22 16:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-22 16:41 Niklas Cassel [this message]
2024-03-22 17:03 ` [PATCH v4] misc: pci_endpoint_test: Use memcpy_toio()/memcpy_fromio() for BAR tests Kuppuswamy Sathyanarayanan
2024-03-25 7:58 ` Niklas Cassel
2024-04-18 9:08 ` Niklas Cassel
2024-04-18 17:49 ` Kuppuswamy Sathyanarayanan
2024-05-04 14:34 ` Manivannan Sadhasivam
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