>-----Original Message-----
>From: Cédric Le Goater <c...@redhat.com>
>Sent: Tuesday, November 14, 2023 9:29 PM
>Subject: Re: [PATCH v6 01/21] backends/iommufd: Introduce the iommufd object
>
>On 11/14/23 11:09, Zhenzhong Duan wrote:
>> From: Eric Auger <eric.au...@redhat.com>
>>
>> Introduce an iommufd object which allows the interaction
>> with the host /dev/iommu device.
>>
>> The /dev/iommu can have been already pre-opened outside of qemu,
>> in which case the fd can be passed directly along with the
>> iommufd object:
>>
>> This allows the iommufd object to be shared accross several
>> subsystems (VFIO, VDPA, ...). For example, libvirt would open
>> the /dev/iommu once.
>>
>> If no fd is passed along with the iommufd object, the /dev/iommu
>> is opened by the qemu code.
>>
>> Suggested-by: Alex Williamson <alex.william...@redhat.com>
>> Signed-off-by: Eric Auger <eric.au...@redhat.com>
>> Signed-off-by: Yi Liu <yi.l....@intel.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
>
>I simplified the object declaration in include/sysemu/iommufd.h and
>formatted /dev/iommu in qemu-options.hx. No need to resend.
Good catch, thanks! Maybe further simplified with below? This is minor.
OBJECT_DECLARE_TYPE(IOMMUFDBackend, IOMMUFDBackendClass, IOMMUFD_BACKEND)
Thanks
Zhenzhong
>
>Reviewed-by: Cédric Le Goater <c...@redhat.com>
>
>Thanks,
>
>C.
>
>
>> ---
>> v6: remove redundant call, alloc_hwpt, get/put_ioas
>>
>> MAINTAINERS | 7 ++
>> qapi/qom.json | 19 ++++
>> include/sysemu/iommufd.h | 44 ++++++++
>> backends/iommufd.c | 228
>+++++++++++++++++++++++++++++++++++++++
>> backends/Kconfig | 4 +
>> backends/meson.build | 1 +
>> backends/trace-events | 10 ++
>> qemu-options.hx | 12 +++
>> 8 files changed, 325 insertions(+)
>> create mode 100644 include/sysemu/iommufd.h
>> create mode 100644 backends/iommufd.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index ff1238bb98..a4891f7bda 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -2166,6 +2166,13 @@ F: hw/vfio/ap.c
>> F: docs/system/s390x/vfio-ap.rst
>> L: qemu-s3...@nongnu.org
>>
>> +iommufd
>> +M: Yi Liu <yi.l....@intel.com>
>> +M: Eric Auger <eric.au...@redhat.com>
>> +S: Supported
>> +F: backends/iommufd.c
>> +F: include/sysemu/iommufd.h
>> +
>> vhost
>> M: Michael S. Tsirkin <m...@redhat.com>
>> S: Supported
>> diff --git a/qapi/qom.json b/qapi/qom.json
>> index c53ef978ff..1fd8555a75 100644
>> --- a/qapi/qom.json
>> +++ b/qapi/qom.json
>> @@ -794,6 +794,23 @@
>> { 'struct': 'VfioUserServerProperties',
>> 'data': { 'socket': 'SocketAddress', 'device': 'str' } }
>>
>> +##
>> +# @IOMMUFDProperties:
>> +#
>> +# Properties for iommufd objects.
>> +#
>> +# @fd: file descriptor name previously passed via 'getfd' command,
>> +# which represents a pre-opened /dev/iommu. This allows the
>> +# iommufd object to be shared accross several subsystems
>> +# (VFIO, VDPA, ...), and the file descriptor to be shared
>> +# with other process, e.g. DPDK. (default: QEMU opens
>> +# /dev/iommu by itself)
>> +#
>> +# Since: 8.2
>> +##
>> +{ 'struct': 'IOMMUFDProperties',
>> + 'data': { '*fd': 'str' } }
>> +
>> ##
>> # @RngProperties:
>> #
>> @@ -934,6 +951,7 @@
>> 'input-barrier',
>> { 'name': 'input-linux',
>> 'if': 'CONFIG_LINUX' },
>> + 'iommufd',
>> 'iothread',
>> 'main-loop',
>> { 'name': 'memory-backend-epc',
>> @@ -1003,6 +1021,7 @@
>> 'input-barrier': 'InputBarrierProperties',
>> 'input-linux': { 'type': 'InputLinuxProperties',
>> 'if': 'CONFIG_LINUX' },
>> + 'iommufd': 'IOMMUFDProperties',
>> 'iothread': 'IothreadProperties',
>> 'main-loop': 'MainLoopProperties',
>> 'memory-backend-epc': { 'type': 'MemoryBackendEpcProperties',
>> diff --git a/include/sysemu/iommufd.h b/include/sysemu/iommufd.h
>> new file mode 100644
>> index 0000000000..9b3a86f57d
>> --- /dev/null
>> +++ b/include/sysemu/iommufd.h
>> @@ -0,0 +1,44 @@
>> +#ifndef SYSEMU_IOMMUFD_H
>> +#define SYSEMU_IOMMUFD_H
>> +
>> +#include "qom/object.h"
>> +#include "qemu/thread.h"
>> +#include "exec/hwaddr.h"
>> +#include "exec/cpu-common.h"
>> +
>> +#define TYPE_IOMMUFD_BACKEND "iommufd"
>> +OBJECT_DECLARE_TYPE(IOMMUFDBackend, IOMMUFDBackendClass,
>> + IOMMUFD_BACKEND)
>> +#define IOMMUFD_BACKEND(obj) \
>> + OBJECT_CHECK(IOMMUFDBackend, (obj), TYPE_IOMMUFD_BACKEND)
>> +#define IOMMUFD_BACKEND_GET_CLASS(obj) \
>> + OBJECT_GET_CLASS(IOMMUFDBackendClass, (obj),
>TYPE_IOMMUFD_BACKEND)
>> +#define IOMMUFD_BACKEND_CLASS(klass) \
>> + OBJECT_CLASS_CHECK(IOMMUFDBackendClass, (klass),
>TYPE_IOMMUFD_BACKEND)
>> +struct IOMMUFDBackendClass {
>> + ObjectClass parent_class;
>> +};
>> +
>> +struct IOMMUFDBackend {
>> + Object parent;
>> +
>> + /*< protected >*/
>> + int fd; /* /dev/iommu file descriptor */
>> + bool owned; /* is the /dev/iommu opened internally */
>> + QemuMutex lock;
>> + uint32_t users;
>> +
>> + /*< public >*/
>> +};
>> +
>> +int iommufd_backend_connect(IOMMUFDBackend *be, Error **errp);
>> +void iommufd_backend_disconnect(IOMMUFDBackend *be);
>> +
>> +int iommufd_backend_alloc_ioas(IOMMUFDBackend *be, uint32_t *ioas_id,
>> + Error **errp);
>> +void iommufd_backend_free_id(IOMMUFDBackend *be, uint32_t id);
>> +int iommufd_backend_map_dma(IOMMUFDBackend *be, uint32_t ioas_id,
>hwaddr iova,
>> + ram_addr_t size, void *vaddr, bool readonly);
>> +int iommufd_backend_unmap_dma(IOMMUFDBackend *be, uint32_t ioas_id,
>> + hwaddr iova, ram_addr_t size);
>> +#endif
>> diff --git a/backends/iommufd.c b/backends/iommufd.c
>> new file mode 100644
>> index 0000000000..ea3e2a8f85
>> --- /dev/null
>> +++ b/backends/iommufd.c
>> @@ -0,0 +1,228 @@
>> +/*
>> + * iommufd container backend
>> + *
>> + * Copyright (C) 2023 Intel Corporation.
>> + * Copyright Red Hat, Inc. 2023
>> + *
>> + * Authors: Yi Liu <yi.l....@intel.com>
>> + * Eric Auger <eric.au...@redhat.com>
>> + *
>> + * SPDX-License-Identifier: GPL-2.0-or-later
>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include "sysemu/iommufd.h"
>> +#include "qapi/error.h"
>> +#include "qapi/qmp/qerror.h"
>> +#include "qemu/module.h"
>> +#include "qom/object_interfaces.h"
>> +#include "qemu/error-report.h"
>> +#include "monitor/monitor.h"
>> +#include "trace.h"
>> +#include <sys/ioctl.h>
>> +#include <linux/iommufd.h>
>> +
>> +static void iommufd_backend_init(Object *obj)
>> +{
>> + IOMMUFDBackend *be = IOMMUFD_BACKEND(obj);
>> +
>> + be->fd = -1;
>> + be->users = 0;
>> + be->owned = true;
>> + qemu_mutex_init(&be->lock);
>> +}
>> +
>> +static void iommufd_backend_finalize(Object *obj)
>> +{
>> + IOMMUFDBackend *be = IOMMUFD_BACKEND(obj);
>> +
>> + if (be->owned) {
>> + close(be->fd);
>> + be->fd = -1;
>> + }
>> +}
>> +
>> +static void iommufd_backend_set_fd(Object *obj, const char *str, Error
>> **errp)
>> +{
>> + IOMMUFDBackend *be = IOMMUFD_BACKEND(obj);
>> + int fd = -1;
>> +
>> + fd = monitor_fd_param(monitor_cur(), str, errp);
>> + if (fd == -1) {
>> + error_prepend(errp, "Could not parse remote object fd %s:", str);
>> + return;
>> + }
>> + qemu_mutex_lock(&be->lock);
>> + be->fd = fd;
>> + be->owned = false;
>> + qemu_mutex_unlock(&be->lock);
>> + trace_iommu_backend_set_fd(be->fd);
>> +}
>> +
>> +static void iommufd_backend_class_init(ObjectClass *oc, void *data)
>> +{
>> + object_class_property_add_str(oc, "fd", NULL, iommufd_backend_set_fd);
>> +}
>> +
>> +int iommufd_backend_connect(IOMMUFDBackend *be, Error **errp)
>> +{
>> + int fd, ret = 0;
>> +
>> + qemu_mutex_lock(&be->lock);
>> + if (be->users == UINT32_MAX) {
>> + error_setg(errp, "too many connections");
>> + ret = -E2BIG;
>> + goto out;
>> + }
>> + if (be->owned && !be->users) {
>> + fd = qemu_open_old("/dev/iommu", O_RDWR);
>> + if (fd < 0) {
>> + error_setg_errno(errp, errno, "/dev/iommu opening failed");
>> + ret = fd;
>> + goto out;
>> + }
>> + be->fd = fd;
>> + }
>> + be->users++;
>> +out:
>> + trace_iommufd_backend_connect(be->fd, be->owned,
>> + be->users, ret);
>> + qemu_mutex_unlock(&be->lock);
>> + return ret;
>> +}
>> +
>> +void iommufd_backend_disconnect(IOMMUFDBackend *be)
>> +{
>> + qemu_mutex_lock(&be->lock);
>> + if (!be->users) {
>> + goto out;
>> + }
>> + be->users--;
>> + if (!be->users && be->owned) {
>> + close(be->fd);
>> + be->fd = -1;
>> + }
>> +out:
>> + trace_iommufd_backend_disconnect(be->fd, be->users);
>> + qemu_mutex_unlock(&be->lock);
>> +}
>> +
>> +int iommufd_backend_alloc_ioas(IOMMUFDBackend *be, uint32_t *ioas_id,
>> + Error **errp)
>> +{
>> + int ret, fd = be->fd;
>> + struct iommu_ioas_alloc alloc_data = {
>> + .size = sizeof(alloc_data),
>> + .flags = 0,
>> + };
>> +
>> + ret = ioctl(fd, IOMMU_IOAS_ALLOC, &alloc_data);
>> + if (ret) {
>> + error_setg_errno(errp, errno, "Failed to allocate ioas");
>> + return ret;
>> + }
>> +
>> + *ioas_id = alloc_data.out_ioas_id;
>> + trace_iommufd_backend_alloc_ioas(fd, *ioas_id, ret);
>> +
>> + return ret;
>> +}
>> +
>> +void iommufd_backend_free_id(IOMMUFDBackend *be, uint32_t id)
>> +{
>> + int ret, fd = be->fd;
>> + struct iommu_destroy des = {
>> + .size = sizeof(des),
>> + .id = id,
>> + };
>> +
>> + ret = ioctl(fd, IOMMU_DESTROY, &des);
>> + trace_iommufd_backend_free_id(fd, id, ret);
>> + if (ret) {
>> + error_report("Failed to free id: %u %m", id);
>> + }
>> +}
>> +
>> +int iommufd_backend_map_dma(IOMMUFDBackend *be, uint32_t ioas_id,
>hwaddr iova,
>> + ram_addr_t size, void *vaddr, bool readonly)
>> +{
>> + int ret, fd = be->fd;
>> + struct iommu_ioas_map map = {
>> + .size = sizeof(map),
>> + .flags = IOMMU_IOAS_MAP_READABLE |
>> + IOMMU_IOAS_MAP_FIXED_IOVA,
>> + .ioas_id = ioas_id,
>> + .__reserved = 0,
>> + .user_va = (uintptr_t)vaddr,
>> + .iova = iova,
>> + .length = size,
>> + };
>> +
>> + if (!readonly) {
>> + map.flags |= IOMMU_IOAS_MAP_WRITEABLE;
>> + }
>> +
>> + ret = ioctl(fd, IOMMU_IOAS_MAP, &map);
>> + trace_iommufd_backend_map_dma(fd, ioas_id, iova, size,
>> + vaddr, readonly, ret);
>> + if (ret) {
>> + ret = -errno;
>> + error_report("IOMMU_IOAS_MAP failed: %m");
>> + }
>> + return ret;
>> +}
>> +
>> +int iommufd_backend_unmap_dma(IOMMUFDBackend *be, uint32_t ioas_id,
>> + hwaddr iova, ram_addr_t size)
>> +{
>> + int ret, fd = be->fd;
>> + struct iommu_ioas_unmap unmap = {
>> + .size = sizeof(unmap),
>> + .ioas_id = ioas_id,
>> + .iova = iova,
>> + .length = size,
>> + };
>> +
>> + ret = ioctl(fd, IOMMU_IOAS_UNMAP, &unmap);
>> + /*
>> + * IOMMUFD takes mapping as some kind of object, unmapping
>> + * nonexistent mapping is treated as deleting a nonexistent
>> + * object and return ENOENT. This is different from legacy
>> + * backend which allows it. vIOMMU may trigger a lot of
>> + * redundant unmapping, to avoid flush the log, treat them
>> + * as succeess for IOMMUFD just like legacy backend.
>> + */
>> + if (ret && errno == ENOENT) {
>> + trace_iommufd_backend_unmap_dma_non_exist(fd, ioas_id, iova, size,
>ret);
>> + ret = 0;
>> + } else {
>> + trace_iommufd_backend_unmap_dma(fd, ioas_id, iova, size, ret);
>> + }
>> +
>> + if (ret) {
>> + ret = -errno;
>> + error_report("IOMMU_IOAS_UNMAP failed: %m");
>> + }
>> + return ret;
>> +}
>> +
>> +static const TypeInfo iommufd_backend_info = {
>> + .name = TYPE_IOMMUFD_BACKEND,
>> + .parent = TYPE_OBJECT,
>> + .instance_size = sizeof(IOMMUFDBackend),
>> + .instance_init = iommufd_backend_init,
>> + .instance_finalize = iommufd_backend_finalize,
>> + .class_size = sizeof(IOMMUFDBackendClass),
>> + .class_init = iommufd_backend_class_init,
>> + .interfaces = (InterfaceInfo[]) {
>> + { TYPE_USER_CREATABLE },
>> + { }
>> + }
>> +};
>> +
>> +static void register_types(void)
>> +{
>> + type_register_static(&iommufd_backend_info);
>> +}
>> +
>> +type_init(register_types);
>> diff --git a/backends/Kconfig b/backends/Kconfig
>> index f35abc1609..2cb23f62fa 100644
>> --- a/backends/Kconfig
>> +++ b/backends/Kconfig
>> @@ -1 +1,5 @@
>> source tpm/Kconfig
>> +
>> +config IOMMUFD
>> + bool
>> + depends on VFIO
>> diff --git a/backends/meson.build b/backends/meson.build
>> index 914c7c4afb..9a5cea480d 100644
>> --- a/backends/meson.build
>> +++ b/backends/meson.build
>> @@ -20,6 +20,7 @@ if have_vhost_user
>> system_ss.add(when: 'CONFIG_VIRTIO', if_true: files('vhost-user.c'))
>> endif
>> system_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('cryptodev-
>vhost.c'))
>> +system_ss.add(when: 'CONFIG_IOMMUFD', if_true: files('iommufd.c'))
>> if have_vhost_user_crypto
>> system_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('cryptodev-
>vhost-user.c'))
>> endif
>> diff --git a/backends/trace-events b/backends/trace-events
>> index 652eb76a57..d45c6e31a6 100644
>> --- a/backends/trace-events
>> +++ b/backends/trace-events
>> @@ -5,3 +5,13 @@ dbus_vmstate_pre_save(void)
>> dbus_vmstate_post_load(int version_id) "version_id: %d"
>> dbus_vmstate_loading(const char *id) "id: %s"
>> dbus_vmstate_saving(const char *id) "id: %s"
>> +
>> +# iommufd.c
>> +iommufd_backend_connect(int fd, bool owned, uint32_t users, int ret) "fd=%d
>owned=%d users=%d (%d)"
>> +iommufd_backend_disconnect(int fd, uint32_t users) "fd=%d users=%d"
>> +iommu_backend_set_fd(int fd) "pre-opened /dev/iommu fd=%d"
>> +iommufd_backend_map_dma(int iommufd, uint32_t ioas, uint64_t iova,
>uint64_t size, void *vaddr, bool readonly, int ret) " iommufd=%d ioas=%d
>iova=0x%"PRIx64" size=0x%"PRIx64" addr=%p readonly=%d (%d)"
>> +iommufd_backend_unmap_dma_non_exist(int iommufd, uint32_t ioas,
>uint64_t iova, uint64_t size, int ret) " Unmap nonexistent mapping: iommufd=%d
>ioas=%d iova=0x%"PRIx64" size=0x%"PRIx64" (%d)"
>> +iommufd_backend_unmap_dma(int iommufd, uint32_t ioas, uint64_t iova,
>uint64_t size, int ret) " iommufd=%d ioas=%d iova=0x%"PRIx64"
>size=0x%"PRIx64" (%d)"
>> +iommufd_backend_alloc_ioas(int iommufd, uint32_t ioas, int ret) "
>iommufd=%d ioas=%d (%d)"
>> +iommufd_backend_free_id(int iommufd, uint32_t id, int ret) " iommufd=%d
>id=%d (%d)"
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 42fd09e4de..70507c0ee6 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -5224,6 +5224,18 @@ SRST
>>
>> The ``share`` boolean option is on by default with memfd.
>>
>> + ``-object iommufd,id=id[,fd=fd]``
>> + Creates an iommufd backend which allows control of DMA mapping
>> + through the /dev/iommu device.
>> +
>> + The ``id`` parameter is a unique ID which frontends (such as
>> + vfio-pci of vdpa) will use to connect with the iommufd backend.
>> +
>> + The ``fd`` parameter is an optional pre-opened file descriptor
>> + resulting from /dev/iommu opening. Usually the iommufd is shared
>> + across all subsystems, bringing the benefit of centralized
>> + reference counting.
>> +
>> ``-object rng-builtin,id=id``
>> Creates a random number generator backend which obtains entropy
>> from QEMU builtin functions. The ``id`` parameter is a unique ID
