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X-IronPort-AV: E=McAfee;i="6600,9927,11020"; a="17579321" X-IronPort-AV: E=Sophos;i="6.07,146,1708416000"; d="scan'208";a="17579321" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2024 10:03:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,146,1708416000"; d="scan'208";a="14867296" Received: from sgreig-mobl1.amr.corp.intel.com (HELO [10.209.63.173]) ([10.209.63.173]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2024 10:03:13 -0700 Message-ID: <8dcb72ed-ee39-4fd6-a157-b7d889f35056@linux.intel.com> Date: Fri, 22 Mar 2024 10:03:12 -0700 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] misc: pci_endpoint_test: Use memcpy_toio()/memcpy_fromio() for BAR tests Content-Language: en-US To: Niklas Cassel , Manivannan Sadhasivam , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Arnd Bergmann , Greg Kroah-Hartman Cc: Damien Le Moal , linux-pci@vger.kernel.org References: <20240322164139.678228-1-cassel@kernel.org> From: Kuppuswamy Sathyanarayanan In-Reply-To: <20240322164139.678228-1-cassel@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/22/24 9:41 AM, Niklas Cassel wrote: > 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 > --- > 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 > +#include > #include > #include > #include > @@ -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; Please check the following cleanup doc. Recommendation is to avoid above __free(kfree) = NULL declarations and directly define write_buf/read_buf. https://lore.kernel.org/lkml/171097196970.1011049.9726486429680041876.stgit@dwillia2-xfh.jf.intel.com/T/#m05d71a668ff0fad46c2055dbdcde55d7381780b7 > 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; > } -- Sathyanarayanan Kuppuswamy Linux Kernel Developer