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The dcbm (DMA core batch migrator) provides a generic interface using DMAEngine for end-to-end testing of the batch page migration offload feature. This facilitates testing and validation of the functionality. Enable DCBM offload: echo 1 > /sys/kernel/dcbm/offloading Disable DCBM offload: echo 0 > /sys/kernel/dcbm/offloading Signed-off-by: Shivank Garg --- drivers/dma/Kconfig | 2 + drivers/dma/Makefile | 1 + drivers/dma/dcbm/Kconfig | 7 ++ drivers/dma/dcbm/Makefile | 1 + drivers/dma/dcbm/dcbm.c | 229 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 240 insertions(+) create mode 100644 drivers/dma/dcbm/Kconfig create mode 100644 drivers/dma/dcbm/Makefile create mode 100644 drivers/dma/dcbm/dcbm.c diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig index e928f2ca0f1e..376bd13d46f8 100644 --- a/drivers/dma/Kconfig +++ b/drivers/dma/Kconfig @@ -750,6 +750,8 @@ config XILINX_ZYNQMP_DPDMA # driver files source "drivers/dma/bestcomm/Kconfig" +source "drivers/dma/dcbm/Kconfig" + source "drivers/dma/mediatek/Kconfig" source "drivers/dma/ptdma/Kconfig" diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile index dfd40d14e408..7d67fc29bce2 100644 --- a/drivers/dma/Makefile +++ b/drivers/dma/Makefile @@ -22,6 +22,7 @@ obj-$(CONFIG_AT_HDMAC) += at_hdmac.o obj-$(CONFIG_AT_XDMAC) += at_xdmac.o obj-$(CONFIG_AXI_DMAC) += dma-axi-dmac.o obj-$(CONFIG_BCM_SBA_RAID) += bcm-sba-raid.o +obj-$(CONFIG_DCBM_DMA) += dcbm/ obj-$(CONFIG_DMA_BCM2835) += bcm2835-dma.o obj-$(CONFIG_DMA_JZ4780) += dma-jz4780.o obj-$(CONFIG_DMA_SA11X0) += sa11x0-dma.o diff --git a/drivers/dma/dcbm/Kconfig b/drivers/dma/dcbm/Kconfig new file mode 100644 index 000000000000..e58eca03fb52 --- /dev/null +++ b/drivers/dma/dcbm/Kconfig @@ -0,0 +1,7 @@ +config DCBM_DMA + bool "DMA Core Batch Migrator" + depends on DMA_ENGINE + default n + help + Interface driver for batch page migration offloading. Say Y + if you want to try offloading with DMAEngine APIs. diff --git a/drivers/dma/dcbm/Makefile b/drivers/dma/dcbm/Makefile new file mode 100644 index 000000000000..56ba47cce0f1 --- /dev/null +++ b/drivers/dma/dcbm/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_DCBM_DMA) += dcbm.o diff --git a/drivers/dma/dcbm/dcbm.c b/drivers/dma/dcbm/dcbm.c new file mode 100644 index 000000000000..dac87fa55327 --- /dev/null +++ b/drivers/dma/dcbm/dcbm.c @@ -0,0 +1,229 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * DMA batch-offlading interface driver + * + * Copyright (C) 2024 Advanced Micro Devices, Inc. + */ + +/* + * This code exemplifies how to leverage mm layer's migration offload support + * for batch page offloading using DMA Engine APIs. + * Developers can use this template to write interface for custom hardware + * accelerators with specialized capabilities for batch page migration. + * This interface driver is end-to-end working and can be used for testing the + * patch series without special hardware given DMAEngine support is available. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static struct dma_chan *chan; +static int is_dispatching; + +static void folios_copy_dma(struct list_head *dst_list, struct list_head *src_list); +static bool can_migrate_dma(struct folio *dst, struct folio *src); + +static DEFINE_MUTEX(migratecfg_mutex); + +/* DMA Core Batch Migrator */ +struct migrator dmigrator = { + .name = "DCBM\0", + .migrate_dma = folios_copy_dma, + .can_migrate_dma = can_migrate_dma, + .owner = THIS_MODULE, +}; + +static ssize_t offloading_set(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int ccode; + int action; + dma_cap_mask_t mask; + + ccode = kstrtoint(buf, 0, &action); + if (ccode) { + pr_debug("(%s:) error parsing input %s\n", __func__, buf); + return ccode; + } + + /* + * action is 0: User wants to disable DMA offloading. + * action is 1: User wants to enable DMA offloading. + */ + switch (action) { + case 0: + mutex_lock(&migratecfg_mutex); + if (is_dispatching == 1) { + stop_offloading(); + dma_release_channel(chan); + is_dispatching = 0; + } else + pr_debug("migration offloading is already OFF\n"); + mutex_unlock(&migratecfg_mutex); + break; + case 1: + mutex_lock(&migratecfg_mutex); + if (is_dispatching == 0) { + dma_cap_zero(mask); + dma_cap_set(DMA_MEMCPY, mask); + chan = dma_request_channel(mask, NULL, NULL); + if (!chan) { + chan = ERR_PTR(-ENODEV); + pr_err("Error requesting DMA channel\n"); + mutex_unlock(&migratecfg_mutex); + return -ENODEV; + } + start_offloading(&dmigrator); + is_dispatching = 1; + } else + pr_debug("migration offloading is already ON\n"); + mutex_unlock(&migratecfg_mutex); + break; + default: + pr_debug("input should be zero or one, parsed as %d\n", action); + } + return sizeof(action); +} + +static ssize_t offloading_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", is_dispatching); +} + +static bool can_migrate_dma(struct folio *dst, struct folio *src) +{ + if (folio_test_hugetlb(src) || folio_test_hugetlb(dst) || + folio_has_private(src) || folio_has_private(dst) || + (folio_nr_pages(src) != folio_nr_pages(dst)) || + folio_nr_pages(src) != 1) + return false; + return true; +} + +static void folios_copy_dma(struct list_head *dst_list, + struct list_head *src_list) +{ + int ret = 0; + struct folio *src, *dst; + struct dma_device *dev; + struct device *dma_dev; + static dma_cookie_t cookie; + struct dma_async_tx_descriptor *tx; + enum dma_status status; + enum dma_ctrl_flags flags = DMA_CTRL_ACK; + dma_addr_t srcdma_handle; + dma_addr_t dstdma_handle; + + + if (!chan) { + pr_err("error chan uninitialized\n"); + goto fail; + } + dev = chan->device; + if (!dev) { + pr_err("error dev is NULL\n"); + goto fail; + } + dma_dev = dmaengine_get_dma_device(chan); + if (!dma_dev) { + pr_err("error dma_dev is NULL\n"); + goto fail; + } + dst = list_first_entry(dst_list, struct folio, lru); + list_for_each_entry(src, src_list, lru) { + srcdma_handle = dma_map_page(dma_dev, &src->page, 0, 4096, DMA_BIDIRECTIONAL); + ret = dma_mapping_error(dma_dev, srcdma_handle); + if (ret) { + pr_err("src mapping error\n"); + goto fail1; + } + dstdma_handle = dma_map_page(dma_dev, &dst->page, 0, 4096, DMA_BIDIRECTIONAL); + ret = dma_mapping_error(dma_dev, dstdma_handle); + if (ret) { + pr_err("dst mapping error\n"); + goto fail2; + } + tx = dev->device_prep_dma_memcpy(chan, dstdma_handle, srcdma_handle, 4096, flags); + if (!tx) { + ret = -EBUSY; + pr_err("prep_dma_error\n"); + goto fail3; + } + cookie = tx->tx_submit(tx); + if (dma_submit_error(cookie)) { + ret = -EINVAL; + pr_err("dma_submit_error\n"); + goto fail3; + } + status = dma_sync_wait(chan, cookie); + dmaengine_terminate_sync(chan); + if (status != DMA_COMPLETE) { + ret = -EINVAL; + pr_err("error while dma wait\n"); + goto fail3; + } +fail3: + dma_unmap_page(dma_dev, dstdma_handle, 4096, DMA_BIDIRECTIONAL); +fail2: + dma_unmap_page(dma_dev, srcdma_handle, 4096, DMA_BIDIRECTIONAL); +fail1: + if (ret) + folio_copy(dst, src); + + dst = list_next_entry(dst, lru); + } +fail: + folios_copy(dst_list, src_list); +} + +static struct kobject *kobj_ref; +static struct kobj_attribute offloading_attribute = __ATTR(offloading, 0664, + offloading_show, offloading_set); + +static int __init dma_module_init(void) +{ + int ret = 0; + + kobj_ref = kobject_create_and_add("dcbm", kernel_kobj); + if (!kobj_ref) + return -ENOMEM; + + ret = sysfs_create_file(kobj_ref, &offloading_attribute.attr); + if (ret) + goto out; + + is_dispatching = 0; + + return 0; +out: + kobject_put(kobj_ref); + return ret; +} + +static void __exit dma_module_exit(void) +{ + /* Stop the DMA offloading to unload the module */ + + //sysfs_remove_file(kobj, &offloading_show.attr); + kobject_put(kobj_ref); +} + +module_init(dma_module_init); +module_exit(dma_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Shivank Garg"); +MODULE_DESCRIPTION("DCBM"); /* DMA Core Batch Migrator */