devemu_pci_device_db_host_sample.c

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 * provided that the following conditions are met:
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 *       conditions and the following disclaimer.
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#include <errno.h>
#include <linux/vfio.h>
#include <sys/ioctl.h>
#include <sys/eventfd.h>
#include <unistd.h>
 
#include <doca_error.h>
#include <doca_log.h>
 
#include <common.h>
#include <devemu_pci_common.h>
#include <devemu_pci_host_common.h>
 
DOCA_LOG_REGISTER(DEVEMU_PCI_DEVICE_DB_HOST);
 
/*
 * Run DOCA Device Emulation DB Host sample
 *
 * @pci_address [in]: Emulated device PCI address
 * @vfio_group [in]: VFIO group ID
 * @region_idx [in]: The index of the DB region
 * @db_idx [in]: The index of the DB in the DB region
 * @db_value [in]: The value to write to the DB
 * @return: DOCA_SUCCESS on success and DOCA_ERROR otherwise
 */
doca_error_t devemu_pci_device_db_host(const char *pci_address,
                       int vfio_group,
                       int region_idx,
                       uint16_t db_idx,
                       uint32_t db_value)
{
    doca_error_t result;
    struct devemu_host_resources resources = {0};
 
    resources.container_fd = -1;
    resources.group_fd = -1;
    resources.device_fd = -1;
 
    const struct bar_db_region_config *db_region_cfg = &db_configs[region_idx];
    size_t db_stride_size = (1UL << db_region_cfg->log_db_stride_size);
    size_t db_offset = db_idx * db_stride_size;
    if (db_offset > (db_region_cfg->region.size - sizeof(uint32_t))) {
        DOCA_LOG_ERR("The given DB index falls outside the DB region");
        return DOCA_ERROR_INVALID_VALUE;
    }
 
    result = init_vfio_device(&resources, vfio_group, pci_address);
    if (result != DOCA_SUCCESS) {
        devemu_host_resources_cleanup(&resources);
        return result;
    }
 
    result = map_bar_region_memory(&resources, &db_region_cfg->region, &resources.db_region);
    if (result != DOCA_SUCCESS) {
        devemu_host_resources_cleanup(&resources);
        return result;
    }
 
    /* Ring the DoorBell */
    *((uint32_t *)&resources.db_region.mem[db_offset]) = db_value;
 
    DOCA_LOG_INFO("Wrote a DB value of %u (BigEndian) at offset %zu", db_value, db_offset);
 
    return DOCA_SUCCESS;
}