>-----Original Message-----
>From: Cédric Le Goater <c...@redhat.com>
>Sent: Monday, November 13, 2023 7:05 PM
>Subject: Re: [PATCH v5 03/20] vfio/iommufd: Implement the iommufd backend
>
>On 11/10/23 11:18, Duan, Zhenzhong wrote:
>>
>>
>>> -----Original Message-----
>>> From: Cédric Le Goater <c...@redhat.com>
>>> Sent: Friday, November 10, 2023 5:34 PM
>>> Subject: Re: [PATCH v5 03/20] vfio/iommufd: Implement the iommufd
>backend
>>>
>>> On 11/9/23 12:45, Zhenzhong Duan wrote:
>>>> From: Yi Liu <yi.l....@intel.com>
>>>>
>>>> Add the iommufd backend. The IOMMUFD container class is implemented
>>>> based on the new /dev/iommu user API. This backend obviously depends
>>>> on CONFIG_IOMMUFD.
>>>>
>>>> So far, the iommufd backend doesn't support dirty page sync yet due
>>>> to missing support in the host kernel.
>>>>
>>>> Co-authored-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>
>>>> ---
>>>> v5: Switch to IOAS attach/detach and hide hwpt
>>>>
>>>> include/hw/vfio/vfio-common.h | 11 +
>>>> hw/vfio/common.c | 20 +-
>>>> hw/vfio/iommufd.c | 429 ++++++++++++++++++++++++++++++++++
>>>> hw/vfio/meson.build | 3 +
>>>> hw/vfio/trace-events | 10 +
>>>> 5 files changed, 469 insertions(+), 4 deletions(-)
>>>> create mode 100644 hw/vfio/iommufd.c
>>>>
>>>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-
>common.h
>>>> index 24ecc0e7ee..3dac5c167e 100644
>>>> --- a/include/hw/vfio/vfio-common.h
>>>> +++ b/include/hw/vfio/vfio-common.h
>>>> @@ -89,6 +89,14 @@ typedef struct VFIOHostDMAWindow {
>>>> QLIST_ENTRY(VFIOHostDMAWindow) hostwin_next;
>>>> } VFIOHostDMAWindow;
>>>>
>>>> +typedef struct IOMMUFDBackend IOMMUFDBackend;
>>>> +
>>>> +typedef struct VFIOIOMMUFDContainer {
>>>> + VFIOContainerBase bcontainer;
>>>> + IOMMUFDBackend *be;
>>>> + uint32_t ioas_id;
>>>> +} VFIOIOMMUFDContainer;
>>>> +
>>>> typedef struct VFIODeviceOps VFIODeviceOps;
>>>>
>>>> typedef struct VFIODevice {
>>>> @@ -116,6 +124,8 @@ typedef struct VFIODevice {
>>>> OnOffAuto pre_copy_dirty_page_tracking;
>>>> bool dirty_pages_supported;
>>>> bool dirty_tracking;
>>>> + int devid;
>>>> + IOMMUFDBackend *iommufd;
>>>> } VFIODevice;
>>>>
>>>> struct VFIODeviceOps {
>>>> @@ -201,6 +211,7 @@ typedef QLIST_HEAD(VFIODeviceList, VFIODevice)
>>> VFIODeviceList;
>>>> extern VFIOGroupList vfio_group_list;
>>>> extern VFIODeviceList vfio_device_list;
>>>> extern const VFIOIOMMUOps vfio_legacy_ops;
>>>> +extern const VFIOIOMMUOps vfio_iommufd_ops;
>>>> extern const MemoryListener vfio_memory_listener;
>>>> extern int vfio_kvm_device_fd;
>>>>
>>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>>>> index 572ae7c934..3b7e11158f 100644
>>>> --- a/hw/vfio/common.c
>>>> +++ b/hw/vfio/common.c
>>>> @@ -19,6 +19,7 @@
>>>> */
>>>>
>>>> #include "qemu/osdep.h"
>>>> +#include CONFIG_DEVICES /* CONFIG_IOMMUFD */
>>>> #include <sys/ioctl.h>
>>>> #ifdef CONFIG_KVM
>>>> #include <linux/kvm.h>
>>>> @@ -1462,10 +1463,13 @@ VFIOAddressSpace
>>> *vfio_get_address_space(AddressSpace *as)
>>>>
>>>> void vfio_put_address_space(VFIOAddressSpace *space)
>>>> {
>>>> - if (QLIST_EMPTY(&space->containers)) {
>>>> - QLIST_REMOVE(space, list);
>>>> - g_free(space);
>>>> + if (!QLIST_EMPTY(&space->containers)) {
>>>> + return;
>>>
>>> I think this change deserves to be in a separate patch, even if simple.
>>> Is there some relation with iommufd ? This is not clear.
>>
>> OK, will do. It's unrelated to iommufd, just avoid unnecessary check below.
>>
>>>
>>>> }
>>>> +
>>>> + QLIST_REMOVE(space, list);
>>>> + g_free(space);
>>>> +
>>>> if (QLIST_EMPTY(&vfio_address_spaces)) {
>>>> qemu_unregister_reset(vfio_reset_handler, NULL);
>>>> }
>>>> @@ -1498,8 +1502,16 @@ retry:
>>>> int vfio_attach_device(char *name, VFIODevice *vbasedev,
>>>> AddressSpace *as, Error **errp)
>>>> {
>>>> - const VFIOIOMMUOps *ops = &vfio_legacy_ops;
>>>> + const VFIOIOMMUOps *ops;
>>>>
>>>> +#ifdef CONFIG_IOMMUFD
>>>> + if (vbasedev->iommufd) {
>>>> + ops = &vfio_iommufd_ops;
>>>> + } else
>>>> +#endif
>>>> + {
>>>> + ops = &vfio_legacy_ops;
>>>> + }
>>>
>>> Simply adding :
>>>
>>> +#ifdef CONFIG_IOMMUFD
>>> + if (vbasedev->iommufd) {
>>> + ops = &vfio_iommufd_ops;
>>> + }
>>> +#endif
>>>
>>> would have the same effect with less change.
>>
>> Indeed, will do.
>>
>>>
>>> That said, it would also be nice to find a way to avoid the use of
>>> CONFIG_IOMMUFD in hw/vfio/common.c. May be with a helper returning
>>> 'const VFIOIOMMUOps *'. This is minor. Still, I find some redundancy
>>> with vfio_container_init() and I don't a good alternative yet :)
>>
>> Sure, will do, guess you mean a helper function in hw/vfio/helpers.c with
>> CONFIG_IOMMUFD check?
>
>Yes. That was the idea. I took a look and the benefits are minimal.
>I am not sure it is worth the effort.
So you are neutral, then I'd like to keep it😊
In fact, we have removed almost all CONFIG_IOMMUFD checks, this is the only one
in common.c, Looks no difference of this check in common.c or helpers.c for me.
>
>I also tried to minize the use of CONFIG_IOMMUFD in our various
>VFIO devices with an intermediate QOM interface. See below.
>
>+
>+#define TYPE_IOMMUFD_INTERFACE "iommufd-interface"
>+#define IOMMUFD_INTERFACE(obj) \
>+ INTERFACE_CHECK(IOMMUFDInterface, (obj), TYPE_IOMMUFD_INTERFACE)
>+typedef struct IOMMUFDInterfaceClass IOMMUFDInterfaceClass;
>+DECLARE_CLASS_CHECKERS(IOMMUFDInterfaceClass, IOMMUFD_INTERFACE,
>+ TYPE_IOMMUFD_INTERFACE)
>+
>+typedef struct IOMMUFDInterface IOMMUFDInterface;
>+
>+struct IOMMUFDInterfaceClass {
>+ InterfaceClass parent;
>+ void (*set_fd)(Object *obj, const char *str, Error **errp);
>+};
>+
>+#ifdef CONFIG_IOMMUFD
>+static void iommufd_interface_set_fd(Object *obj, const char *str, Error
>**errp)
>+{
>+ IOMMUFDInterfaceClass *iik = IOMMUFD_INTERFACE_GET_CLASS(obj);
>+
>+ iik->set_fd(obj, str, errp);
>+}
>+#endif
>+
>+static void iommufd_interface_class_init(ObjectClass *klass, void *data)
>+{
>+#ifdef CONFIG_IOMMUFD
>+ object_class_property_add_str(klass, "fd", NULL,
>iommufd_interface_set_fd);
>+#endif
>+}
>+
>+static void iommufd_interface_add_property(Object *obj, Object **iommufd)
>+{
>+#ifdef CONFIG_IOMMUFD
>+ object_property_add_link(obj, "iommufd", TYPE_IOMMUFD_BACKEND,
>iommufd,
>+ NULL, OBJ_PROP_LINK_STRONG);
>+#endif
>+}
>+
>+static const TypeInfo iommufd_interface_info = {
>+ .name = TYPE_IOMMUFD_INTERFACE,
>+ .parent = TYPE_INTERFACE,
>+ .class_size = sizeof(IOMMUFDInterfaceClass),
>+ .class_init = iommufd_interface_class_init,
>+};
>
> /*
> * Functions used whatever the injection method
>@@ -649,21 +696,18 @@ static Property vfio_platform_dev_proper
> static void vfio_platform_instance_init(Object *obj)
> {
> VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(obj);
>+ Object *iommufd = OBJECT(vdev->vbasedev.iommufd);
>
> vdev->vbasedev.fd = -1;
>+ iommufd_interface_add_property(obj, &iommufd);
> }
>
> static void vfio_platform_class_init(ObjectClass *klass, void *data)
> {
> DeviceClass *dc = DEVICE_CLASS(klass);
> SysBusDeviceClass *sbc = SYS_BUS_DEVICE_CLASS(klass);
>+ IOMMUFDInterfaceClass *iik = IOMMUFD_INTERFACE_CLASS(klass);
>
> dc->realize = vfio_platform_realize;
> device_class_set_props(dc, vfio_platform_dev_properties);
> dc->vmsd = &vfio_platform_vmstate;
> dc->desc = "VFIO-based platform device assignment";
> sbc->connect_irq_notifier = vfio_start_irqfd_injection;
> set_bit(DEVICE_CATEGORY_MISC, dc->categories);
> /* Supported by TYPE_VIRT_MACHINE */
> dc->user_creatable = true;
>+ iik->set_fd = vfio_platform_set_fd;
> }
>
> static const TypeInfo vfio_platform_dev_info = {
>@@ -703,11 +745,16 @@ static const TypeInfo vfio_platform_dev_
> .instance_init = vfio_platform_instance_init,
> .class_init = vfio_platform_class_init,
> .class_size = sizeof(VFIOPlatformDeviceClass),
>+ .interfaces = (InterfaceInfo[]) {
>+ { TYPE_IOMMUFD_INTERFACE },
>+ { }
>+ }
> };
>
>
>Not really satisfying compared to the #ifdef. Let's keep them.
Still nice try out, thanks
>
>
>
>>
>>>
>>>
>>>> return ops->attach_device(name, vbasedev, as, errp);
>>>> }
>>>>
>>>> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
>>>> new file mode 100644
>>>> index 0000000000..ea4e23f4ec
>>>> --- /dev/null
>>>> +++ b/hw/vfio/iommufd.c
>>>> @@ -0,0 +1,429 @@
>>>> +/*
>>>> + * 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 <sys/ioctl.h>
>>>> +#include <linux/vfio.h>
>>>> +#include <linux/iommufd.h>
>>>> +
>>>> +#include "hw/vfio/vfio-common.h"
>>>> +#include "qemu/error-report.h"
>>>> +#include "trace.h"
>>>> +#include "qapi/error.h"
>>>> +#include "sysemu/iommufd.h"
>>>> +#include "hw/qdev-core.h"
>>>> +#include "sysemu/reset.h"
>>>> +#include "qemu/cutils.h"
>>>> +#include "qemu/chardev_open.h"
>>>> +
>>>> +static int iommufd_map(VFIOContainerBase *bcontainer, hwaddr iova,
>>>> + ram_addr_t size, void *vaddr, bool readonly)
>>>> +{
>>>> + VFIOIOMMUFDContainer *container =
>>>> + container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
>>>> +
>>>> + return iommufd_backend_map_dma(container->be,
>>>> + container->ioas_id,
>>>> + iova, size, vaddr, readonly);
>>>> +}
>>>> +
>>>> +static int iommufd_unmap(VFIOContainerBase *bcontainer,
>>>> + hwaddr iova, ram_addr_t size,
>>>> + IOMMUTLBEntry *iotlb)
>>>> +{
>>>> + VFIOIOMMUFDContainer *container =
>>>> + container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
>>>> +
>>>> + /* TODO: Handle dma_unmap_bitmap with iotlb args (migration) */
>>>> + return iommufd_backend_unmap_dma(container->be,
>>>> + container->ioas_id, iova, size);
>>>> +}
>>>> +
>>>> +static void iommufd_cdev_kvm_device_add(VFIODevice *vbasedev)
>>>> +{
>>>> + Error *err = NULL;
>>>> +
>>>> + if (vfio_kvm_device_add_fd(vbasedev->fd, &err)) {
>>>> + error_report_err(err);
>>>
>>> We should propagate this error to the callers instead.
>>
>> This is to follow legacy backend where the error doesn't treated as
>> a serious issue.
>>
>>>
>>>> + }
>>>> +}
>>>> +
>>>> +static void iommufd_cdev_kvm_device_del(VFIODevice *vbasedev)
>>>> +{
>>>> + Error *err = NULL;
>>>> +
>>>> + if (vfio_kvm_device_del_fd(vbasedev->fd, &err)) {
>>>> + error_report_err(err);
>>>
>>> Possibly this one also but It might be more complex. Let's keep it that
>>> way.
>>>
>>>> + }
>>>> +}
>>>> +
>>>> +static int iommufd_connect_and_bind(VFIODevice *vbasedev, Error **errp)
>>>> +{
>>>> + IOMMUFDBackend *iommufd = vbasedev->iommufd;
>>>> + struct vfio_device_bind_iommufd bind = {
>>>> + .argsz = sizeof(bind),
>>>> + .flags = 0,
>>>> + };
>>>> + int ret;
>>>> +
>>>> + ret = iommufd_backend_connect(iommufd, errp);
>>>> + if (ret) {
>>>> + return ret;
>>>> + }
>>>> +
>>>> + /*
>>>> + * Add device to kvm-vfio to be prepared for the tracking
>>>> + * in KVM. Especially for some emulated devices, it requires
>>>> + * to have kvm information in the device open.
>>>> + */
>>>> + iommufd_cdev_kvm_device_add(vbasedev);
>>>
>>> We shoud return a possible error.
>>
>> This is to follow legacy backend where this error is reported and ignored.
>> Do we need a difference for iommufd BE?
>
>I don't know ! You tell me :) It is always better to raise the
>exception and let the upper layers decide on the action to take.
Got it, will fix.
>
>>
>>>
>>>> +
>>>> + /* Bind device to iommufd */
>>>> + bind.iommufd = iommufd->fd;
>>>> + ret = ioctl(vbasedev->fd, VFIO_DEVICE_BIND_IOMMUFD, &bind);
>>>> + if (ret) {
>>>> + error_setg_errno(errp, errno, "error bind device fd=%d to
>iommufd=%d",
>>>> + vbasedev->fd, bind.iommufd);
>>>> + goto err_bind;
>>>> + }
>>>> +
>>>> + vbasedev->devid = bind.out_devid;
>>>> + trace_iommufd_connect_and_bind(bind.iommufd, vbasedev->name,
>>> vbasedev->fd,
>>>> + vbasedev->devid);
>>>> + return ret;
>>>> +err_bind:
>>>> + iommufd_cdev_kvm_device_del(vbasedev);
>>>> + iommufd_backend_disconnect(iommufd);
>>>
>>> These two calls look like iommufd_unbind_and_disconnect() below.
>>
>> Yes, they are same as iommufd doesn't support explicit device unbind.
>> But it looks strange to call iommufd_unbind_and_disconnect in
>> iommufd_connect_and_bind.
>
>This is just a little redudant. This is minor.
With above fix, there is a new label in between, so not an issue now.
Thanks
Zhenzhong
