ddio.c

/*
 * Changing DDIO State
 *
 * Copyright (c) 2020, Alireza Farshin, KTH Royal Institute of Technology - All Rights Reserved
 */

#include <stdio.h>
#include <stdlib.h>
#include <pci/pci.h>
#include <sys/io.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <inttypes.h>
#include <unistd.h>

#include "utils.h"

#define PCI_VENDOR_ID_INTEL   	0x8086
#define SKX_PERFCTRLSTS_0	0x180
#define SKX_use_allocating_flow_wr_MASK 0x80
#define SKX_nosnoopopwren_MASK	0x8

/*
 * Find the proper pci device (i.e., PCIe Root Port) based on the nic device
 * For instance, if the NIC is located on 0000:17:00.0 (i.e., BDF)
 * 0x17 is the nic_bus (B)
 * 0x00 is the nic_device (D)
 * 0x0  is the nic_function (F)
 */

struct pci_access *pacc;

void
init_pci_access(void)
{
	pacc = pci_alloc();           /* Get the pci_access structure */
	pci_init(pacc);               /* Initialize the PCI library */
	pci_scan_bus(pacc);           /* We want to get the list of devices */
}

struct pci_dev*
find_ddio_device(uint8_t nic_bus)
{
	struct pci_dev* dev;
	for(dev = pacc->devices; dev; dev=dev->next) {
		pci_fill_info(dev,PCI_FILL_IDENT | PCI_FILL_BASES | PCI_FILL_NUMA_NODE | PCI_FILL_PHYS_SLOT);
		/*
		 * Find the proper PCIe root based on the nic device
		 * For instance, if the NIC is located on 0000:17:00.0 (i.e., BDF)
		 * 0x17 is the nic_bus (B)
		 * 0x00 is the nic_device (D)
		 * 0x0	is the nic_function (F)
		 * TODO: Fix this for Haswell, i.e., 03:00.0 -- Dev and Fun might be different
		 */
		if(/*dev->func == 0 && dev->dev == 0  && */pci_read_byte(dev,PCI_SUBORDINATE_BUS) == nic_bus /*&& dev->numa_node==1 && dev->domain==0x10001*/) {
			return dev;
		}
	}
	pr_err("Could not find the proper PCIe root!");
	return NULL;
}


/*
 * perfctrlsts_0
 * bit 3: NoSnoopOpWrEn -> Should be 1b
 * bit 7: Use_Allocating_Flow_Wr -> Should be 0b
 * Check p. 68 of Intel® Xeon® Processor Scalable Family
 * Datasheet, Volume Two: Registers
 * May 2019
 * link: https://www.intel.com/content/www/us/en/processors/xeon/scalable/xeon-scalable-datasheet-vol-2.html
 */
int
ddio_status(uint8_t nic_bus)
{
	uint32_t val;
	if(!pacc)
		init_pci_access();

	struct pci_dev* dev=find_ddio_device(nic_bus);
	if(!dev){
		pr_err("No device found!");
		exit(1);
	}
	val=pci_read_long(dev,SKX_PERFCTRLSTS_0);
	if(val&SKX_use_allocating_flow_wr_MASK)
		return 1;
	else
		return 0;
}

void
ddio_enable(uint8_t nic_bus)
{
	uint32_t val;
	if(!pacc)
		init_pci_access();

	if(!ddio_status(nic_bus))
	{
		struct pci_dev* dev=find_ddio_device(nic_bus);
		if(!dev){
                	pr_err("No device found!");
                	exit(1);
        	}
		val=pci_read_long(dev,SKX_PERFCTRLSTS_0);
		pci_write_long(dev,SKX_PERFCTRLSTS_0,val|SKX_use_allocating_flow_wr_MASK);
		pr_info("DDIO is enabled!");
	} else
	{
		pr_info("DDIO was already enabled!");
	}
}

void
ddio_disable(uint8_t nic_bus)
{
	uint32_t val;
	if(!pacc)
		init_pci_access();

        if(ddio_status(nic_bus))
        {
		struct pci_dev* dev=find_ddio_device(nic_bus);
		if(!dev){
                	pr_err("No device found!");
                	exit(1);
		}
                val=pci_read_long(dev,SKX_PERFCTRLSTS_0);
                pci_write_long(dev,SKX_PERFCTRLSTS_0,val&(~SKX_use_allocating_flow_wr_MASK));
		pr_info("DDIO is disabled!");
        } else
	{
		pr_info("DDIO was already disabled");
	}
}

void
print_dev_info(struct pci_dev *dev)
{
	if(!dev){
		pr_err("No device found!");
		exit(1);
        }
	unsigned int c;
	char namebuf[1024], *name;
	name = pci_lookup_name(pacc, namebuf, sizeof(namebuf), PCI_LOOKUP_DEVICE, dev->vendor_id, dev->device_id);
	pr_info("pci_dev %04x:%02x:%02x.%d vendor=%04x device=%04x class=%04x irq=%d (pin %d) base0=%lx (%s)",
             dev->domain, dev->bus, dev->dev, dev->func, dev->vendor_id, dev->device_id,
             dev->device_class, dev->irq, c, (long) dev->base_addr[0], name);
}

int main(void)
{
  init_pci_access();

  /* Define nic_bus and ddio_state */
  uint8_t nic_bus=0x3b, ddio_state=0;

  struct pci_dev *dev=find_ddio_device(nic_bus);
  print_dev_info(dev);

  if(ddio_state) {
	  ddio_enable(nic_bus);
  } else {
	  ddio_disable(nic_bus);
  }

  pci_cleanup(pacc);		/* Close everything */
  return 0;
}