hw/pci/msi.c - qemu - Git at Google

 /*
  * msi.c
  *
  * Copyright (c) 2010 Isaku Yamahata <yamahata at valinux co jp>
  *                    VA Linux Systems Japan K.K.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.

  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.

  * You should have received a copy of the GNU General Public License along
  * with this program; if not, see <http://www.gnu.org/licenses/>.
  */

 #include "qemu/osdep.h"
 #include "hw/pci/msi.h"
 #include "hw/xen/xen.h"
 #include "qemu/range.h"

 /* PCI_MSI_ADDRESS_LO */
 #define PCI_MSI_ADDRESS_LO_MASK         (~0x3)

 /* If we get rid of cap allocator, we won't need those. */
 #define PCI_MSI_32_SIZEOF       0x0a
 #define PCI_MSI_64_SIZEOF       0x0e
 #define PCI_MSI_32M_SIZEOF      0x14
 #define PCI_MSI_64M_SIZEOF      0x18

 #define PCI_MSI_VECTORS_MAX     32

 /* Flag for interrupt controller to declare MSI/MSI-X support */
 bool msi_supported;

 /* If we get rid of cap allocator, we won't need this. */
 static inline uint8_t msi_cap_sizeof(uint16_t flags)
 {
     switch (flags & (PCI_MSI_FLAGS_MASKBIT | PCI_MSI_FLAGS_64BIT)) {
     case PCI_MSI_FLAGS_MASKBIT | PCI_MSI_FLAGS_64BIT:
         return PCI_MSI_64M_SIZEOF;
     case PCI_MSI_FLAGS_64BIT:
         return PCI_MSI_64_SIZEOF;
     case PCI_MSI_FLAGS_MASKBIT:
         return PCI_MSI_32M_SIZEOF;
     case 0:
         return PCI_MSI_32_SIZEOF;
     default:
         abort();
         break;
     }
     return 0;
 }

 //#define MSI_DEBUG

 #ifdef MSI_DEBUG
 # define MSI_DPRINTF(fmt, ...)                                          \
     fprintf(stderr, "%s:%d " fmt, __func__, __LINE__, ## __VA_ARGS__)
 #else
 # define MSI_DPRINTF(fmt, ...)  do { } while (0)
 #endif
 #define MSI_DEV_PRINTF(dev, fmt, ...)                                   \
     MSI_DPRINTF("%s:%x " fmt, (dev)->name, (dev)->devfn, ## __VA_ARGS__)

 static inline unsigned int msi_nr_vectors(uint16_t flags)
 {
     return 1U <<
         ((flags & PCI_MSI_FLAGS_QSIZE) >> ctz32(PCI_MSI_FLAGS_QSIZE));
 }

 static inline uint8_t msi_flags_off(const PCIDevice* dev)
 {
     return dev->msi_cap + PCI_MSI_FLAGS;
 }

 static inline uint8_t msi_address_lo_off(const PCIDevice* dev)
 {
     return dev->msi_cap + PCI_MSI_ADDRESS_LO;
 }

 static inline uint8_t msi_address_hi_off(const PCIDevice* dev)
 {
     return dev->msi_cap + PCI_MSI_ADDRESS_HI;
 }

 static inline uint8_t msi_data_off(const PCIDevice* dev, bool msi64bit)
 {
     return dev->msi_cap + (msi64bit ? PCI_MSI_DATA_64 : PCI_MSI_DATA_32);
 }

 static inline uint8_t msi_mask_off(const PCIDevice* dev, bool msi64bit)
 {
     return dev->msi_cap + (msi64bit ? PCI_MSI_MASK_64 : PCI_MSI_MASK_32);
 }

 static inline uint8_t msi_pending_off(const PCIDevice* dev, bool msi64bit)
 {
     return dev->msi_cap + (msi64bit ? PCI_MSI_PENDING_64 : PCI_MSI_PENDING_32);
 }

 /*
  * Special API for POWER to configure the vectors through
  * a side channel. Should never be used by devices.
  */
 void msi_set_message(PCIDevice *dev, MSIMessage msg)
 {
     uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
     bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;

     if (msi64bit) {
         pci_set_quad(dev->config + msi_address_lo_off(dev), msg.address);
     } else {
         pci_set_long(dev->config + msi_address_lo_off(dev), msg.address);
     }
     pci_set_word(dev->config + msi_data_off(dev, msi64bit), msg.data);
 }

 MSIMessage msi_get_message(PCIDevice *dev, unsigned int vector)
 {
     uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
     bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
     unsigned int nr_vectors = msi_nr_vectors(flags);
     MSIMessage msg;

     assert(vector < nr_vectors);

     if (msi64bit) {
         msg.address = pci_get_quad(dev->config + msi_address_lo_off(dev));
     } else {
         msg.address = pci_get_long(dev->config + msi_address_lo_off(dev));
     }

     /* upper bit 31:16 is zero */
     msg.data = pci_get_word(dev->config + msi_data_off(dev, msi64bit));
     if (nr_vectors > 1) {
         msg.data &= ~(nr_vectors - 1);
         msg.data |= vector;
     }

     return msg;
 }

 bool msi_enabled(const PCIDevice *dev)
 {
     return msi_present(dev) &&
         (pci_get_word(dev->config + msi_flags_off(dev)) &
          PCI_MSI_FLAGS_ENABLE);
 }

 int msi_init(struct PCIDevice *dev, uint8_t offset,
              unsigned int nr_vectors, bool msi64bit, bool msi_per_vector_mask)
 {
     unsigned int vectors_order;
     uint16_t flags;
     uint8_t cap_size;
     int config_offset;

     if (!msi_supported) {
         return -ENOTSUP;
     }

     MSI_DEV_PRINTF(dev,
                    "init offset: 0x%"PRIx8" vector: %"PRId8
                    " 64bit %d mask %d\n",
                    offset, nr_vectors, msi64bit, msi_per_vector_mask);

     assert(!(nr_vectors & (nr_vectors - 1)));   /* power of 2 */
     assert(nr_vectors > 0);
     assert(nr_vectors <= PCI_MSI_VECTORS_MAX);
     /* the nr of MSI vectors is up to 32 */
     vectors_order = ctz32(nr_vectors);

     flags = vectors_order << ctz32(PCI_MSI_FLAGS_QMASK);
     if (msi64bit) {
         flags |= PCI_MSI_FLAGS_64BIT;
     }
     if (msi_per_vector_mask) {
         flags |= PCI_MSI_FLAGS_MASKBIT;
     }

     cap_size = msi_cap_sizeof(flags);
     config_offset = pci_add_capability(dev, PCI_CAP_ID_MSI, offset, cap_size);
     if (config_offset < 0) {
         return config_offset;
     }

     dev->msi_cap = config_offset;
     dev->cap_present |= QEMU_PCI_CAP_MSI;

     pci_set_word(dev->config + msi_flags_off(dev), flags);
     pci_set_word(dev->wmask + msi_flags_off(dev),
                  PCI_MSI_FLAGS_QSIZE | PCI_MSI_FLAGS_ENABLE);
     pci_set_long(dev->wmask + msi_address_lo_off(dev),
                  PCI_MSI_ADDRESS_LO_MASK);
     if (msi64bit) {
         pci_set_long(dev->wmask + msi_address_hi_off(dev), 0xffffffff);
     }
     pci_set_word(dev->wmask + msi_data_off(dev, msi64bit), 0xffff);

     if (msi_per_vector_mask) {
         /* Make mask bits 0 to nr_vectors - 1 writable. */
         pci_set_long(dev->wmask + msi_mask_off(dev, msi64bit),
                      0xffffffff >> (PCI_MSI_VECTORS_MAX - nr_vectors));
     }
     return config_offset;
 }

 void msi_uninit(struct PCIDevice *dev)
 {
     uint16_t flags;
     uint8_t cap_size;

     if (!msi_present(dev)) {
         return;
     }
     flags = pci_get_word(dev->config + msi_flags_off(dev));
     cap_size = msi_cap_sizeof(flags);
     pci_del_capability(dev, PCI_CAP_ID_MSI, cap_size);
     dev->cap_present &= ~QEMU_PCI_CAP_MSI;

     MSI_DEV_PRINTF(dev, "uninit\n");
 }

 void msi_reset(PCIDevice *dev)
 {
     uint16_t flags;
     bool msi64bit;

     if (!msi_present(dev)) {
         return;
     }

     flags = pci_get_word(dev->config + msi_flags_off(dev));
     flags &= ~(PCI_MSI_FLAGS_QSIZE | PCI_MSI_FLAGS_ENABLE);
     msi64bit = flags & PCI_MSI_FLAGS_64BIT;

     pci_set_word(dev->config + msi_flags_off(dev), flags);
     pci_set_long(dev->config + msi_address_lo_off(dev), 0);
     if (msi64bit) {
         pci_set_long(dev->config + msi_address_hi_off(dev), 0);
     }
     pci_set_word(dev->config + msi_data_off(dev, msi64bit), 0);
     if (flags & PCI_MSI_FLAGS_MASKBIT) {
         pci_set_long(dev->config + msi_mask_off(dev, msi64bit), 0);
         pci_set_long(dev->config + msi_pending_off(dev, msi64bit), 0);
     }
     MSI_DEV_PRINTF(dev, "reset\n");
 }

 static bool msi_is_masked(const PCIDevice *dev, unsigned int vector)
 {
     uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
     uint32_t mask, data;
     bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
     assert(vector < PCI_MSI_VECTORS_MAX);

     if (!(flags & PCI_MSI_FLAGS_MASKBIT)) {
         return false;
     }

     data = pci_get_word(dev->config + msi_data_off(dev, msi64bit));
     if (xen_is_pirq_msi(data)) {
         return false;
     }

     mask = pci_get_long(dev->config +
                         msi_mask_off(dev, flags & PCI_MSI_FLAGS_64BIT));
     return mask & (1U << vector);
 }

 void msi_notify(PCIDevice *dev, unsigned int vector)
 {
     uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
     bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
     unsigned int nr_vectors = msi_nr_vectors(flags);
     MSIMessage msg;

     assert(vector < nr_vectors);
     if (msi_is_masked(dev, vector)) {
         assert(flags & PCI_MSI_FLAGS_MASKBIT);
         pci_long_test_and_set_mask(
             dev->config + msi_pending_off(dev, msi64bit), 1U << vector);
         MSI_DEV_PRINTF(dev, "pending vector 0x%x\n", vector);
         return;
     }

     msg = msi_get_message(dev, vector);

     MSI_DEV_PRINTF(dev,
                    "notify vector 0x%x"
                    " address: 0x%"PRIx64" data: 0x%"PRIx32"\n",
                    vector, msg.address, msg.data);
     msi_send_message(dev, msg);
 }

 void msi_send_message(PCIDevice *dev, MSIMessage msg)
 {
     MemTxAttrs attrs = {};

     attrs.requester_id = pci_requester_id(dev);
     address_space_stl_le(&dev->bus_master_as, msg.address, msg.data,
                          attrs, NULL);
 }

 /* Normally called by pci_default_write_config(). */
 void msi_write_config(PCIDevice *dev, uint32_t addr, uint32_t val, int len)
 {
     uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
     bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
     bool msi_per_vector_mask = flags & PCI_MSI_FLAGS_MASKBIT;
     unsigned int nr_vectors;
     uint8_t log_num_vecs;
     uint8_t log_max_vecs;
     unsigned int vector;
     uint32_t pending;

     if (!msi_present(dev) ||
         !ranges_overlap(addr, len, dev->msi_cap, msi_cap_sizeof(flags))) {
         return;
     }

 #ifdef MSI_DEBUG
     MSI_DEV_PRINTF(dev, "addr 0x%"PRIx32" val 0x%"PRIx32" len %d\n",
                    addr, val, len);
     MSI_DEV_PRINTF(dev, "ctrl: 0x%"PRIx16" address: 0x%"PRIx32,
                    flags,
                    pci_get_long(dev->config + msi_address_lo_off(dev)));
     if (msi64bit) {
         fprintf(stderr, " address-hi: 0x%"PRIx32,
                 pci_get_long(dev->config + msi_address_hi_off(dev)));
     }
     fprintf(stderr, " data: 0x%"PRIx16,
             pci_get_word(dev->config + msi_data_off(dev, msi64bit)));
     if (flags & PCI_MSI_FLAGS_MASKBIT) {
         fprintf(stderr, " mask 0x%"PRIx32" pending 0x%"PRIx32,
                 pci_get_long(dev->config + msi_mask_off(dev, msi64bit)),
                 pci_get_long(dev->config + msi_pending_off(dev, msi64bit)));
     }
     fprintf(stderr, "\n");
 #endif

     if (!(flags & PCI_MSI_FLAGS_ENABLE)) {
         return;
     }

     /*
      * Now MSI is enabled, clear INTx# interrupts.
      * the driver is prohibited from writing enable bit to mask
      * a service request. But the guest OS could do this.
      * So we just discard the interrupts as moderate fallback.
      *
      * 6.8.3.3. Enabling Operation
      *   While enabled for MSI or MSI-X operation, a function is prohibited
      *   from using its INTx# pin (if implemented) to request
      *   service (MSI, MSI-X, and INTx# are mutually exclusive).
      */
     pci_device_deassert_intx(dev);

     /*
      * nr_vectors might be set bigger than capable. So clamp it.
      * This is not legal by spec, so we can do anything we like,
      * just don't crash the host
      */
     log_num_vecs =
         (flags & PCI_MSI_FLAGS_QSIZE) >> ctz32(PCI_MSI_FLAGS_QSIZE);
     log_max_vecs =
         (flags & PCI_MSI_FLAGS_QMASK) >> ctz32(PCI_MSI_FLAGS_QMASK);
     if (log_num_vecs > log_max_vecs) {
         flags &= ~PCI_MSI_FLAGS_QSIZE;
         flags |= log_max_vecs << ctz32(PCI_MSI_FLAGS_QSIZE);
         pci_set_word(dev->config + msi_flags_off(dev), flags);
     }

     if (!msi_per_vector_mask) {
         /* if per vector masking isn't supported,
            there is no pending interrupt. */
         return;
     }

     nr_vectors = msi_nr_vectors(flags);

     /* This will discard pending interrupts, if any. */
     pending = pci_get_long(dev->config + msi_pending_off(dev, msi64bit));
     pending &= 0xffffffff >> (PCI_MSI_VECTORS_MAX - nr_vectors);
     pci_set_long(dev->config + msi_pending_off(dev, msi64bit), pending);

     /* deliver pending interrupts which are unmasked */
     for (vector = 0; vector < nr_vectors; ++vector) {
         if (msi_is_masked(dev, vector) || !(pending & (1U << vector))) {
             continue;
         }

         pci_long_test_and_clear_mask(
             dev->config + msi_pending_off(dev, msi64bit), 1U << vector);
         msi_notify(dev, vector);
     }
 }

 unsigned int msi_nr_vectors_allocated(const PCIDevice *dev)
 {
     uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
     return msi_nr_vectors(flags);
 }
	/*
	* msi.c
	*
	* Copyright (c) 2010 Isaku Yamahata <yamahata at valinux co jp>
	* VA Linux Systems Japan K.K.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.

	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.

	* You should have received a copy of the GNU General Public License along
	* with this program; if not, see <http://www.gnu.org/licenses/>.
	*/

	#include "qemu/osdep.h"
	#include "hw/pci/msi.h"
	#include "hw/xen/xen.h"
	#include "qemu/range.h"

	/* PCI_MSI_ADDRESS_LO */
	#define PCI_MSI_ADDRESS_LO_MASK (~0x3)

	/* If we get rid of cap allocator, we won't need those. */
	#define PCI_MSI_32_SIZEOF 0x0a
	#define PCI_MSI_64_SIZEOF 0x0e
	#define PCI_MSI_32M_SIZEOF 0x14
	#define PCI_MSI_64M_SIZEOF 0x18

	#define PCI_MSI_VECTORS_MAX 32

	/* Flag for interrupt controller to declare MSI/MSI-X support */
	bool msi_supported;

	/* If we get rid of cap allocator, we won't need this. */
	static inline uint8_t msi_cap_sizeof(uint16_t flags)
	{
	switch (flags & (PCI_MSI_FLAGS_MASKBIT \| PCI_MSI_FLAGS_64BIT)) {
	case PCI_MSI_FLAGS_MASKBIT \| PCI_MSI_FLAGS_64BIT:
	return PCI_MSI_64M_SIZEOF;
	case PCI_MSI_FLAGS_64BIT:
	return PCI_MSI_64_SIZEOF;
	case PCI_MSI_FLAGS_MASKBIT:
	return PCI_MSI_32M_SIZEOF;
	case 0:
	return PCI_MSI_32_SIZEOF;
	default:
	abort();
	break;
	}
	return 0;
	}

	//#define MSI_DEBUG

	#ifdef MSI_DEBUG
	# define MSI_DPRINTF(fmt, ...) \
	fprintf(stderr, "%s:%d " fmt, __func__, __LINE__, ## __VA_ARGS__)
	#else
	# define MSI_DPRINTF(fmt, ...) do { } while (0)
	#endif
	#define MSI_DEV_PRINTF(dev, fmt, ...) \
	MSI_DPRINTF("%s:%x " fmt, (dev)->name, (dev)->devfn, ## __VA_ARGS__)

	static inline unsigned int msi_nr_vectors(uint16_t flags)
	{
	return 1U <<
	((flags & PCI_MSI_FLAGS_QSIZE) >> ctz32(PCI_MSI_FLAGS_QSIZE));
	}

	static inline uint8_t msi_flags_off(const PCIDevice* dev)
	{
	return dev->msi_cap + PCI_MSI_FLAGS;
	}

	static inline uint8_t msi_address_lo_off(const PCIDevice* dev)
	{
	return dev->msi_cap + PCI_MSI_ADDRESS_LO;
	}

	static inline uint8_t msi_address_hi_off(const PCIDevice* dev)
	{
	return dev->msi_cap + PCI_MSI_ADDRESS_HI;
	}

	static inline uint8_t msi_data_off(const PCIDevice* dev, bool msi64bit)
	{
	return dev->msi_cap + (msi64bit ? PCI_MSI_DATA_64 : PCI_MSI_DATA_32);
	}

	static inline uint8_t msi_mask_off(const PCIDevice* dev, bool msi64bit)
	{
	return dev->msi_cap + (msi64bit ? PCI_MSI_MASK_64 : PCI_MSI_MASK_32);
	}

	static inline uint8_t msi_pending_off(const PCIDevice* dev, bool msi64bit)
	{
	return dev->msi_cap + (msi64bit ? PCI_MSI_PENDING_64 : PCI_MSI_PENDING_32);
	}

	/*
	* Special API for POWER to configure the vectors through
	* a side channel. Should never be used by devices.
	*/
	void msi_set_message(PCIDevice *dev, MSIMessage msg)
	{
	uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
	bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;

	if (msi64bit) {
	pci_set_quad(dev->config + msi_address_lo_off(dev), msg.address);
	} else {
	pci_set_long(dev->config + msi_address_lo_off(dev), msg.address);
	}
	pci_set_word(dev->config + msi_data_off(dev, msi64bit), msg.data);
	}

	MSIMessage msi_get_message(PCIDevice *dev, unsigned int vector)
	{
	uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
	bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
	unsigned int nr_vectors = msi_nr_vectors(flags);
	MSIMessage msg;

	assert(vector < nr_vectors);

	if (msi64bit) {
	msg.address = pci_get_quad(dev->config + msi_address_lo_off(dev));
	} else {
	msg.address = pci_get_long(dev->config + msi_address_lo_off(dev));
	}

	/* upper bit 31:16 is zero */
	msg.data = pci_get_word(dev->config + msi_data_off(dev, msi64bit));
	if (nr_vectors > 1) {
	msg.data &= ~(nr_vectors - 1);
	msg.data \|= vector;
	}

	return msg;
	}

	bool msi_enabled(const PCIDevice *dev)
	{
	return msi_present(dev) &&
	(pci_get_word(dev->config + msi_flags_off(dev)) &
	PCI_MSI_FLAGS_ENABLE);
	}

	int msi_init(struct PCIDevice *dev, uint8_t offset,
	unsigned int nr_vectors, bool msi64bit, bool msi_per_vector_mask)
	{
	unsigned int vectors_order;
	uint16_t flags;
	uint8_t cap_size;
	int config_offset;

	if (!msi_supported) {
	return -ENOTSUP;
	}

	MSI_DEV_PRINTF(dev,
	"init offset: 0x%"PRIx8" vector: %"PRId8
	" 64bit %d mask %d\n",
	offset, nr_vectors, msi64bit, msi_per_vector_mask);

	assert(!(nr_vectors & (nr_vectors - 1))); /* power of 2 */
	assert(nr_vectors > 0);
	assert(nr_vectors <= PCI_MSI_VECTORS_MAX);
	/* the nr of MSI vectors is up to 32 */
	vectors_order = ctz32(nr_vectors);

	flags = vectors_order << ctz32(PCI_MSI_FLAGS_QMASK);
	if (msi64bit) {
	flags \|= PCI_MSI_FLAGS_64BIT;
	}
	if (msi_per_vector_mask) {
	flags \|= PCI_MSI_FLAGS_MASKBIT;
	}

	cap_size = msi_cap_sizeof(flags);
	config_offset = pci_add_capability(dev, PCI_CAP_ID_MSI, offset, cap_size);
	if (config_offset < 0) {
	return config_offset;
	}

	dev->msi_cap = config_offset;
	dev->cap_present \|= QEMU_PCI_CAP_MSI;

	pci_set_word(dev->config + msi_flags_off(dev), flags);
	pci_set_word(dev->wmask + msi_flags_off(dev),
	PCI_MSI_FLAGS_QSIZE \| PCI_MSI_FLAGS_ENABLE);
	pci_set_long(dev->wmask + msi_address_lo_off(dev),
	PCI_MSI_ADDRESS_LO_MASK);
	if (msi64bit) {
	pci_set_long(dev->wmask + msi_address_hi_off(dev), 0xffffffff);
	}
	pci_set_word(dev->wmask + msi_data_off(dev, msi64bit), 0xffff);

	if (msi_per_vector_mask) {
	/* Make mask bits 0 to nr_vectors - 1 writable. */
	pci_set_long(dev->wmask + msi_mask_off(dev, msi64bit),
	0xffffffff >> (PCI_MSI_VECTORS_MAX - nr_vectors));
	}
	return config_offset;
	}

	void msi_uninit(struct PCIDevice *dev)
	{
	uint16_t flags;
	uint8_t cap_size;

	if (!msi_present(dev)) {
	return;
	}
	flags = pci_get_word(dev->config + msi_flags_off(dev));
	cap_size = msi_cap_sizeof(flags);
	pci_del_capability(dev, PCI_CAP_ID_MSI, cap_size);
	dev->cap_present &= ~QEMU_PCI_CAP_MSI;

	MSI_DEV_PRINTF(dev, "uninit\n");
	}

	void msi_reset(PCIDevice *dev)
	{
	uint16_t flags;
	bool msi64bit;

	if (!msi_present(dev)) {
	return;
	}

	flags = pci_get_word(dev->config + msi_flags_off(dev));
	flags &= ~(PCI_MSI_FLAGS_QSIZE \| PCI_MSI_FLAGS_ENABLE);
	msi64bit = flags & PCI_MSI_FLAGS_64BIT;

	pci_set_word(dev->config + msi_flags_off(dev), flags);
	pci_set_long(dev->config + msi_address_lo_off(dev), 0);
	if (msi64bit) {
	pci_set_long(dev->config + msi_address_hi_off(dev), 0);
	}
	pci_set_word(dev->config + msi_data_off(dev, msi64bit), 0);
	if (flags & PCI_MSI_FLAGS_MASKBIT) {
	pci_set_long(dev->config + msi_mask_off(dev, msi64bit), 0);
	pci_set_long(dev->config + msi_pending_off(dev, msi64bit), 0);
	}
	MSI_DEV_PRINTF(dev, "reset\n");
	}

	static bool msi_is_masked(const PCIDevice *dev, unsigned int vector)
	{
	uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
	uint32_t mask, data;
	bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
	assert(vector < PCI_MSI_VECTORS_MAX);

	if (!(flags & PCI_MSI_FLAGS_MASKBIT)) {
	return false;
	}

	data = pci_get_word(dev->config + msi_data_off(dev, msi64bit));
	if (xen_is_pirq_msi(data)) {
	return false;
	}

	mask = pci_get_long(dev->config +
	msi_mask_off(dev, flags & PCI_MSI_FLAGS_64BIT));
	return mask & (1U << vector);
	}

	void msi_notify(PCIDevice *dev, unsigned int vector)
	{
	uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
	bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
	unsigned int nr_vectors = msi_nr_vectors(flags);
	MSIMessage msg;

	assert(vector < nr_vectors);
	if (msi_is_masked(dev, vector)) {
	assert(flags & PCI_MSI_FLAGS_MASKBIT);
	pci_long_test_and_set_mask(
	dev->config + msi_pending_off(dev, msi64bit), 1U << vector);
	MSI_DEV_PRINTF(dev, "pending vector 0x%x\n", vector);
	return;
	}

	msg = msi_get_message(dev, vector);

	MSI_DEV_PRINTF(dev,
	"notify vector 0x%x"
	" address: 0x%"PRIx64" data: 0x%"PRIx32"\n",
	vector, msg.address, msg.data);
	msi_send_message(dev, msg);
	}

	void msi_send_message(PCIDevice *dev, MSIMessage msg)
	{
	MemTxAttrs attrs = {};

	attrs.requester_id = pci_requester_id(dev);
	address_space_stl_le(&dev->bus_master_as, msg.address, msg.data,
	attrs, NULL);
	}

	/* Normally called by pci_default_write_config(). */
	void msi_write_config(PCIDevice *dev, uint32_t addr, uint32_t val, int len)
	{
	uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
	bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
	bool msi_per_vector_mask = flags & PCI_MSI_FLAGS_MASKBIT;
	unsigned int nr_vectors;
	uint8_t log_num_vecs;
	uint8_t log_max_vecs;
	unsigned int vector;
	uint32_t pending;

	if (!msi_present(dev) \|\|
	!ranges_overlap(addr, len, dev->msi_cap, msi_cap_sizeof(flags))) {
	return;
	}

	#ifdef MSI_DEBUG
	MSI_DEV_PRINTF(dev, "addr 0x%"PRIx32" val 0x%"PRIx32" len %d\n",
	addr, val, len);
	MSI_DEV_PRINTF(dev, "ctrl: 0x%"PRIx16" address: 0x%"PRIx32,
	flags,
	pci_get_long(dev->config + msi_address_lo_off(dev)));
	if (msi64bit) {
	fprintf(stderr, " address-hi: 0x%"PRIx32,
	pci_get_long(dev->config + msi_address_hi_off(dev)));
	}
	fprintf(stderr, " data: 0x%"PRIx16,
	pci_get_word(dev->config + msi_data_off(dev, msi64bit)));
	if (flags & PCI_MSI_FLAGS_MASKBIT) {
	fprintf(stderr, " mask 0x%"PRIx32" pending 0x%"PRIx32,
	pci_get_long(dev->config + msi_mask_off(dev, msi64bit)),
	pci_get_long(dev->config + msi_pending_off(dev, msi64bit)));
	}
	fprintf(stderr, "\n");
	#endif

	if (!(flags & PCI_MSI_FLAGS_ENABLE)) {
	return;
	}

	/*
	* Now MSI is enabled, clear INTx# interrupts.
	* the driver is prohibited from writing enable bit to mask
	* a service request. But the guest OS could do this.
	* So we just discard the interrupts as moderate fallback.
	*
	* 6.8.3.3. Enabling Operation
	* While enabled for MSI or MSI-X operation, a function is prohibited
	* from using its INTx# pin (if implemented) to request
	* service (MSI, MSI-X, and INTx# are mutually exclusive).
	*/
	pci_device_deassert_intx(dev);

	/*
	* nr_vectors might be set bigger than capable. So clamp it.
	* This is not legal by spec, so we can do anything we like,
	* just don't crash the host
	*/
	log_num_vecs =
	(flags & PCI_MSI_FLAGS_QSIZE) >> ctz32(PCI_MSI_FLAGS_QSIZE);
	log_max_vecs =
	(flags & PCI_MSI_FLAGS_QMASK) >> ctz32(PCI_MSI_FLAGS_QMASK);
	if (log_num_vecs > log_max_vecs) {
	flags &= ~PCI_MSI_FLAGS_QSIZE;
	flags \|= log_max_vecs << ctz32(PCI_MSI_FLAGS_QSIZE);
	pci_set_word(dev->config + msi_flags_off(dev), flags);
	}

	if (!msi_per_vector_mask) {
	/* if per vector masking isn't supported,
	there is no pending interrupt. */
	return;
	}

	nr_vectors = msi_nr_vectors(flags);

	/* This will discard pending interrupts, if any. */
	pending = pci_get_long(dev->config + msi_pending_off(dev, msi64bit));
	pending &= 0xffffffff >> (PCI_MSI_VECTORS_MAX - nr_vectors);
	pci_set_long(dev->config + msi_pending_off(dev, msi64bit), pending);

	/* deliver pending interrupts which are unmasked */
	for (vector = 0; vector < nr_vectors; ++vector) {
	if (msi_is_masked(dev, vector) \|\| !(pending & (1U << vector))) {
	continue;
	}

	pci_long_test_and_clear_mask(
	dev->config + msi_pending_off(dev, msi64bit), 1U << vector);
	msi_notify(dev, vector);
	}
	}

	unsigned int msi_nr_vectors_allocated(const PCIDevice *dev)
	{
	uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
	return msi_nr_vectors(flags);
	}