Hi Zhenzhong,
On 11/16/23 05:04, Duan, Zhenzhong wrote:
> Hi Eric,
>
>> -----Original Message-----
>> From: Eric Auger <eric.au...@redhat.com>
>> Sent: Wednesday, November 15, 2023 8:53 PM
>> Subject: Re: [PATCH v6 01/21] backends/iommufd: Introduce the iommufd object
>>
>> Hi Zhenzhong,
>>
>> 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>
>>> ---
>>> 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>
>> Zhenzhong, don't you want to be added here?
>>> +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,
>> "previously passed via 'getfd' command", I wonder if this applies here or
>> whether
>> it is copy/paste of
>> RemoteObjectProperties.fd doc?
> Maybe copied😊 I thinks this applies here because I use monitor_fd_param to
> get fd.
> Or I miss anything?
This is a bit cryptic to me and I don't really understand what it means.
It does not mean it is not correct but I am curious about explanations
if anybody has some ;-)
>
>>> +# 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
>> I don't know the state of vDPA/iommufd integration but this extra might
>> be added in short term.
> Thanks for reminder. But I think it make more sense that series relax the
> check
> itself?
> E.g. depends on VFIO || VHOST_VDPA
yeah we can leave it as it is for now
Eric
>
> Thanks
> Zhenzhong
