Re: [RFC v9 15/29] vfio: Set up nested stage mappings

From: Kunkun Jiang <jiangkunkun@huawei.com>
To: Auger Eric <eric.auger@redhat.com>, <eric.auger.pro@gmail.com>,
	<qemu-devel@nongnu.org>, <qemu-arm@nongnu.org>,
	<alex.williamson@redhat.com>
Cc: peter.maydell@linaro.org, jacob.jun.pan@linux.intel.com,
	chenxiang66@hisilicon.com, tn@semihalf.com,
	shameerali.kolothum.thodi@huawei.com, nicoleotsuka@gmail.com,
	vivek.gautam@arm.com, vdumpa@nvidia.com, yi.l.liu@intel.com,
	peterx@redhat.com, zhangfei.gao@gmail.com,
	wanghaibin.wang@huawei.com, yuzenghui@huawei.com,
	jean-philippe@linaro.org, zhukeqian1@huawei.com
Subject: Re: [RFC v9 15/29] vfio: Set up nested stage mappings
Date: Wed, 28 Apr 2021 17:51:36 +0800	[thread overview]
Message-ID: <639684ad-45c4-3594-8ba0-4f7b45fa272b@huawei.com> (raw)
In-Reply-To: <2a68dca6-e638-4518-f3dd-72fbad0df509@redhat.com>

Hi Eric,

On 2021/4/27 3:16, Auger Eric wrote:
> Hi Kunkun,
>
> On 4/15/21 4:03 AM, Kunkun Jiang wrote:
>> Hi Eric,
>>
>> On 2021/4/14 16:05, Auger Eric wrote:
>>> Hi Kunkun,
>>>
>>> On 4/14/21 3:45 AM, Kunkun Jiang wrote:
>>>> On 2021/4/13 20:57, Auger Eric wrote:
>>>>> Hi Kunkun,
>>>>>
>>>>> On 4/13/21 2:10 PM, Kunkun Jiang wrote:
>>>>>> Hi Eric,
>>>>>>
>>>>>> On 2021/4/11 20:08, Eric Auger wrote:
>>>>>>> In nested mode, legacy vfio_iommu_map_notify cannot be used as
>>>>>>> there is no "caching" mode and we do not trap on map.
>>>>>>>
>>>>>>> On Intel, vfio_iommu_map_notify was used to DMA map the RAM
>>>>>>> through the host single stage.
>>>>>>>
>>>>>>> With nested mode, we need to setup the stage 2 and the stage 1
>>>>>>> separately. This patch introduces a prereg_listener to setup
>>>>>>> the stage 2 mapping.
>>>>>>>
>>>>>>> The stage 1 mapping, owned by the guest, is passed to the host
>>>>>>> when the guest invalidates the stage 1 configuration, through
>>>>>>> a dedicated PCIPASIDOps callback. Guest IOTLB invalidations
>>>>>>> are cascaded downto the host through another IOMMU MR UNMAP
>>>>>>> notifier.
>>>>>>>
>>>>>>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>>>>>>
>>>>>>> ---
>>>>>>>
>>>>>>> v7 -> v8:
>>>>>>> - properly handle new IOMMUTLBEntry fields and especially
>>>>>>>       propagate DOMAIN and PASID based invalidations
>>>>>>>
>>>>>>> v6 -> v7:
>>>>>>> - remove PASID based invalidation
>>>>>>>
>>>>>>> v5 -> v6:
>>>>>>> - add error_report_err()
>>>>>>> - remove the abort in case of nested stage case
>>>>>>>
>>>>>>> v4 -> v5:
>>>>>>> - use VFIO_IOMMU_SET_PASID_TABLE
>>>>>>> - use PCIPASIDOps for config notification
>>>>>>>
>>>>>>> v3 -> v4:
>>>>>>> - use iommu_inv_pasid_info for ASID invalidation
>>>>>>>
>>>>>>> v2 -> v3:
>>>>>>> - use VFIO_IOMMU_ATTACH_PASID_TABLE
>>>>>>> - new user API
>>>>>>> - handle leaf
>>>>>>>
>>>>>>> v1 -> v2:
>>>>>>> - adapt to uapi changes
>>>>>>> - pass the asid
>>>>>>> - pass IOMMU_NOTIFIER_S1_CFG when initializing the config notifier
>>>>>>> ---
>>>>>>>      hw/vfio/common.c     | 139
>>>>>>> +++++++++++++++++++++++++++++++++++++++++--
>>>>>>>      hw/vfio/pci.c        |  21 +++++++
>>>>>>>      hw/vfio/trace-events |   2 +
>>>>>>>      3 files changed, 157 insertions(+), 5 deletions(-)
>>>>>>>
>>>>>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>>>>>>> index 0cd7ef2139..e369d451e7 100644
>>>>>>> --- a/hw/vfio/common.c
>>>>>>> +++ b/hw/vfio/common.c
>>>>>>> @@ -595,6 +595,73 @@ static bool vfio_get_xlat_addr(IOMMUTLBEntry
>>>>>>> *iotlb, void **vaddr,
>>>>>>>          return true;
>>>>>>>      }
>>>>>>>      +/* Propagate a guest IOTLB invalidation to the host (nested
>>>>>>> mode) */
>>>>>>> +static void vfio_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry
>>>>>>> *iotlb)
>>>>>>> +{
>>>>>>> +    VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n);
>>>>>>> +    struct vfio_iommu_type1_cache_invalidate ustruct = {};
>>>>>>> +    VFIOContainer *container = giommu->container;
>>>>>>> +    int ret;
>>>>>>> +
>>>>>>> +    assert(iotlb->perm == IOMMU_NONE);
>>>>>>> +
>>>>>>> +    ustruct.argsz = sizeof(ustruct);
>>>>>>> +    ustruct.flags = 0;
>>>>>>> +    ustruct.info.argsz = sizeof(struct iommu_cache_invalidate_info);
>>>>>>> +    ustruct.info.version = IOMMU_CACHE_INVALIDATE_INFO_VERSION_1;
>>>>>>> +    ustruct.info.cache = IOMMU_CACHE_INV_TYPE_IOTLB;
>>>>>>> +
>>>>>>> +    switch (iotlb->granularity) {
>>>>>>> +    case IOMMU_INV_GRAN_DOMAIN:
>>>>>>> +        ustruct.info.granularity = IOMMU_INV_GRANU_DOMAIN;
>>>>>>> +        break;
>>>>>>> +    case IOMMU_INV_GRAN_PASID:
>>>>>>> +    {
>>>>>>> +        struct iommu_inv_pasid_info *pasid_info;
>>>>>>> +        int archid = -1;
>>>>>>> +
>>>>>>> +        pasid_info = &ustruct.info.granu.pasid_info;
>>>>>>> +        ustruct.info.granularity = IOMMU_INV_GRANU_PASID;
>>>>>>> +        if (iotlb->flags & IOMMU_INV_FLAGS_ARCHID) {
>>>>>>> +            pasid_info->flags |= IOMMU_INV_ADDR_FLAGS_ARCHID;
>>>>>>> +            archid = iotlb->arch_id;
>>>>>>> +        }
>>>>>>> +        pasid_info->archid = archid;
>>>>>>> +        trace_vfio_iommu_asid_inv_iotlb(archid);
>>>>>>> +        break;
>>>>>>> +    }
>>>>>>> +    case IOMMU_INV_GRAN_ADDR:
>>>>>>> +    {
>>>>>>> +        hwaddr start = iotlb->iova + giommu->iommu_offset;
>>>>>>> +        struct iommu_inv_addr_info *addr_info;
>>>>>>> +        size_t size = iotlb->addr_mask + 1;
>>>>>>> +        int archid = -1;
>>>>>>> +
>>>>>>> +        addr_info = &ustruct.info.granu.addr_info;
>>>>>>> +        ustruct.info.granularity = IOMMU_INV_GRANU_ADDR;
>>>>>>> +        if (iotlb->leaf) {
>>>>>>> +            addr_info->flags |= IOMMU_INV_ADDR_FLAGS_LEAF;
>>>>>>> +        }
>>>>>>> +        if (iotlb->flags & IOMMU_INV_FLAGS_ARCHID) {
>>>>>>> +            addr_info->flags |= IOMMU_INV_ADDR_FLAGS_ARCHID;
>>>>>>> +            archid = iotlb->arch_id;
>>>>>>> +        }
>>>>>>> +        addr_info->archid = archid;
>>>>>>> +        addr_info->addr = start;
>>>>>>> +        addr_info->granule_size = size;
>>>>>>> +        addr_info->nb_granules = 1;
>>>>>>> +        trace_vfio_iommu_addr_inv_iotlb(archid, start, size,
>>>>>>> +                                        1, iotlb->leaf);
>>>>>>> +        break;
>>>>>>> +    }
>>>>>> Should we pass a size to  host kernel here, even if vSMMU doesn't
>>>>>> support
>>>>>> RIL or guest kernel doesn't use RIL?
>>>>>>
>>>>>> It will cause TLBI issue in  this scenario: Guest kernel issues a
>>>>>> TLBI cmd
>>>>>> without "range" (tg = 0) to invalidate a 2M huge page. Then qemu
>>>>>> passed
>>>>>> the iova and size (4K) to host kernel. Finally, host kernel issues a
>>>>>> TLBI cmd
>>>>>> with "range" (4K) which can not invalidate the TLB entry of 2M huge
>>>>>> page.
>>>>>> (pSMMU supports RIL)
>>>>> In that case the guest will loop over all 4K images belonging to the 2M
>>>>> huge page and invalidate each of them. This should turn into qemu
>>>>> notifications for each 4kB page, no? This is totally inefficient, hence
>>>> The guest will not loop over all 4K images belonging to the 2M huge
>>>> page.
>>>> The iommu_iotlb_gather->pgsize will be 2M, if a page is 2M huge page.
>>>> The
>>>> gather->pgsize will be passed to __arm_smmu_tlb_inv_range as "granule":
>>>>
>>>> iommu_iotlb_gather_add_page
>>>>       iommu_iotlb_sync
>>>>           domain->ops->iotlb_sync
>>>>               arm_smmu_iotlb_sync
>>>>                   arm_smmu_tlb_inv_range_domain
>>>>                       __arm_smmu_tlb_inv_range
>>>>
>>>> In the above mentioned scenario, guest kernel will issue a TLBI cmd only
>>>> with
>>>> "iova" (tg = 0).
>>> OK I get it now. In that case I think I should do a TG=0 invalidation
>>> on host even if the host does support RIL. Does that sound correct?
>> Yeah, that's what I thought.
>>> The trouble is the uapi struct does not convey such info explicitly.
>>> Maybe I should use nb_granules = 0 to detect that case.
>> It is troublesome to correct this issue. Using nb_granules = 0 may be
>> a good choice.
>>> I think for this use case RIL should be supported by the guest. Thoughts?
>> Yes. If guest supports RIL, the scenario mentioned above does not exist.
> After further study I really wonder if it is worth supporting the case
> where the guest does not use range inval. Passing a nb_granules = 0 (~
> size) would be OK to perform the TG=0 range invalidation on the host.
> however host arm_smmu_tlb_inv_range_domain() then calls
> arm_smmu_atc_inv_domain(smmu_domain, 0, iova, size) which needs a size.
> We would need to trap guest CMD_ATC_INV and use different code paths on
> host smmu driver to cascade the various cache invalidations. At the
> moment, without maintainer giodance, I am a bit reluctant to add this
> extra complexity.
>
> So I would be inclined to fail in QEMU if we detect TG=0 is being used
> by the guest. Recent guest kernels would be a prerequisite for this use
> case. What do you think?
Sorry for late reply.

How do I determine whether the guest kernel is a recent guest kernel?
If I use a modified kernel or an old kernel, this method will cause problems
when the vm runs business.

I didn't think of the problem of CMD_ATC_INV. In my opinion, it is the best
choice to add processing of CMD_ATC_INV. And some function of smmu
driver will issues a separate CMD_ATC_INV, for example
arm_smmu_enable_ats(). Is it possible that Qemu needs to support the
processing of CMD_ATC_INV in the future?

I also thought of another not-so-good idea. We can use the granule_size
to give CMD_ATC_INV a corresponding maximum page size. This will
result in poor performance.
For example:
granule_size          maximum_page_size
       4K                               1G

Thanks,
Kunkun Jiang
> Thanks
>
> Eric
>> Thanks,
>> Kunkun Jiang
>>> Thanks
>>>
>>> Eric
>>>> Thanks,
>>>> Kunkun Jiang
>>>>> the support of RIL on guest side and QEMU device.
>>>>>
>>>>> What do I miss?
>>>>>
>>>>> Thanks
>>>>>
>>>>> Eric
>>>>>> Thanks,
>>>>>> Kunkun Jiang
>>>>>>> +    }
>>>>>>> +
>>>>>>> +    ret = ioctl(container->fd, VFIO_IOMMU_CACHE_INVALIDATE,
>>>>>>> &ustruct);
>>>>>>> +    if (ret) {
>>>>>>> +        error_report("%p: failed to invalidate CACHE (%d)",
>>>>>>> container, ret);
>>>>>>> +    }
>>>>>>> +}
>>>>>>> +
>>>>>>>      static void vfio_iommu_map_notify(IOMMUNotifier *n, IOMMUTLBEntry
>>>>>>> *iotlb)
>>>>>>>      {
>>>>>>>          VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n);
>>>>>>> @@ -776,6 +843,35 @@ static void
>>>>>>> vfio_dma_unmap_ram_section(VFIOContainer *container,
>>>>>>>          }
>>>>>>>      }
>>>>>>>      +static void vfio_prereg_listener_region_add(MemoryListener
>>>>>>> *listener,
>>>>>>> +                                            MemoryRegionSection
>>>>>>> *section)
>>>>>>> +{
>>>>>>> +    VFIOContainer *container =
>>>>>>> +        container_of(listener, VFIOContainer, prereg_listener);
>>>>>>> +    Error *err = NULL;
>>>>>>> +
>>>>>>> +    if (!memory_region_is_ram(section->mr)) {
>>>>>>> +        return;
>>>>>>> +    }
>>>>>>> +
>>>>>>> +    vfio_dma_map_ram_section(container, section, &err);
>>>>>>> +    if (err) {
>>>>>>> +        error_report_err(err);
>>>>>>> +    }
>>>>>>> +}
>>>>>>> +static void vfio_prereg_listener_region_del(MemoryListener
>>>>>>> *listener,
>>>>>>> +                                     MemoryRegionSection *section)
>>>>>>> +{
>>>>>>> +    VFIOContainer *container =
>>>>>>> +        container_of(listener, VFIOContainer, prereg_listener);
>>>>>>> +
>>>>>>> +    if (!memory_region_is_ram(section->mr)) {
>>>>>>> +        return;
>>>>>>> +    }
>>>>>>> +
>>>>>>> +    vfio_dma_unmap_ram_section(container, section);
>>>>>>> +}
>>>>>>> +
>>>>>>>      static void vfio_listener_region_add(MemoryListener *listener,
>>>>>>>                                           MemoryRegionSection
>>>>>>> *section)
>>>>>>>      {
>>>>>>> @@ -879,9 +975,10 @@ static void
>>>>>>> vfio_listener_region_add(MemoryListener *listener,
>>>>>>>          memory_region_ref(section->mr);
>>>>>>>            if (memory_region_is_iommu(section->mr)) {
>>>>>>> +        IOMMUNotify notify;
>>>>>>>              VFIOGuestIOMMU *giommu;
>>>>>>>              IOMMUMemoryRegion *iommu_mr =
>>>>>>> IOMMU_MEMORY_REGION(section->mr);
>>>>>>> -        int iommu_idx;
>>>>>>> +        int iommu_idx, flags;
>>>>>>>                trace_vfio_listener_region_add_iommu(iova, end);
>>>>>>>              /*
>>>>>>> @@ -900,8 +997,18 @@ static void
>>>>>>> vfio_listener_region_add(MemoryListener *listener,
>>>>>>>              llend = int128_sub(llend, int128_one());
>>>>>>>              iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
>>>>>>>                                                          
>>>>>>> MEMTXATTRS_UNSPECIFIED);
>>>>>>> -        iommu_notifier_init(&giommu->n, vfio_iommu_map_notify,
>>>>>>> -                            IOMMU_NOTIFIER_IOTLB_EVENTS,
>>>>>>> +
>>>>>>> +        if (container->iommu_type == VFIO_TYPE1_NESTING_IOMMU) {
>>>>>>> +            /* IOTLB unmap notifier to propagate guest IOTLB
>>>>>>> invalidations */
>>>>>>> +            flags = IOMMU_NOTIFIER_UNMAP;
>>>>>>> +            notify = vfio_iommu_unmap_notify;
>>>>>>> +        } else {
>>>>>>> +            /* MAP/UNMAP IOTLB notifier */
>>>>>>> +            flags = IOMMU_NOTIFIER_IOTLB_EVENTS;
>>>>>>> +            notify = vfio_iommu_map_notify;
>>>>>>> +        }
>>>>>>> +
>>>>>>> +        iommu_notifier_init(&giommu->n, notify, flags,
>>>>>>>                                  section->offset_within_region,
>>>>>>>                                  int128_get64(llend),
>>>>>>>                                  iommu_idx);
>>>>>>> @@ -921,7 +1028,9 @@ static void
>>>>>>> vfio_listener_region_add(MemoryListener *listener,
>>>>>>>                  goto fail;
>>>>>>>              }
>>>>>>>              QLIST_INSERT_HEAD(&container->giommu_list, giommu,
>>>>>>> giommu_next);
>>>>>>> -        memory_region_iommu_replay(giommu->iommu, &giommu->n);
>>>>>>> +        if (flags & IOMMU_NOTIFIER_MAP) {
>>>>>>> +            memory_region_iommu_replay(giommu->iommu, &giommu->n);
>>>>>>> +        }
>>>>>>>                return;
>>>>>>>          }
>>>>>>> @@ -1205,10 +1314,16 @@ static const MemoryListener
>>>>>>> vfio_memory_listener = {
>>>>>>>          .log_sync = vfio_listener_log_sync,
>>>>>>>      };
>>>>>>>      +static MemoryListener vfio_memory_prereg_listener = {
>>>>>>> +    .region_add = vfio_prereg_listener_region_add,
>>>>>>> +    .region_del = vfio_prereg_listener_region_del,
>>>>>>> +};
>>>>>>> +
>>>>>>>      static void vfio_listener_release(VFIOContainer *container)
>>>>>>>      {
>>>>>>>          memory_listener_unregister(&container->listener);
>>>>>>> -    if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
>>>>>>> +    if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU ||
>>>>>>> +        container->iommu_type == VFIO_TYPE1_NESTING_IOMMU) {
>>>>>>>              memory_listener_unregister(&container->prereg_listener);
>>>>>>>          }
>>>>>>>      }
>>>>>>> @@ -1858,6 +1973,20 @@ static int vfio_connect_container(VFIOGroup
>>>>>>> *group, AddressSpace *as,
>>>>>>>                  vfio_get_iommu_info_migration(container, info);
>>>>>>>              }
>>>>>>>              g_free(info);
>>>>>>> +
>>>>>>> +        if (container->iommu_type == VFIO_TYPE1_NESTING_IOMMU) {
>>>>>>> +            container->prereg_listener =
>>>>>>> vfio_memory_prereg_listener;
>>>>>>> +            memory_listener_register(&container->prereg_listener,
>>>>>>> +                                     &address_space_memory);
>>>>>>> +            if (container->error) {
>>>>>>> +
>>>>>>> memory_listener_unregister(&container->prereg_listener);
>>>>>>> +                ret = -1;
>>>>>>> +                error_propagate_prepend(errp, container->error,
>>>>>>> +                                    "RAM memory listener
>>>>>>> initialization failed "
>>>>>>> +                                    "for container");
>>>>>>> +                goto free_container_exit;
>>>>>>> +            }
>>>>>>> +        }
>>>>>>>              break;
>>>>>>>          }
>>>>>>>          case VFIO_SPAPR_TCE_v2_IOMMU:
>>>>>>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>>>>>>> index 5c65aa0a98..cad7deec71 100644
>>>>>>> --- a/hw/vfio/pci.c
>>>>>>> +++ b/hw/vfio/pci.c
>>>>>>> @@ -2773,6 +2773,25 @@ static void
>>>>>>> vfio_unregister_req_notifier(VFIOPCIDevice *vdev)
>>>>>>>          vdev->req_enabled = false;
>>>>>>>      }
>>>>>>>      +static int vfio_iommu_set_pasid_table(PCIBus *bus, int32_t
>>>>>>> devfn,
>>>>>>> +                                      IOMMUConfig *config)
>>>>>>> +{
>>>>>>> +    PCIDevice *pdev = bus->devices[devfn];
>>>>>>> +    VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
>>>>>>> +    VFIOContainer *container = vdev->vbasedev.group->container;
>>>>>>> +    struct vfio_iommu_type1_set_pasid_table info;
>>>>>>> +
>>>>>>> +    info.argsz = sizeof(info);
>>>>>>> +    info.flags = VFIO_PASID_TABLE_FLAG_SET;
>>>>>>> +    memcpy(&info.config, &config->pasid_cfg,
>>>>>>> sizeof(config->pasid_cfg));
>>>>>>> +
>>>>>>> +    return ioctl(container->fd, VFIO_IOMMU_SET_PASID_TABLE, &info);
>>>>>>> +}
>>>>>>> +
>>>>>>> +static PCIPASIDOps vfio_pci_pasid_ops = {
>>>>>>> +    .set_pasid_table = vfio_iommu_set_pasid_table,
>>>>>>> +};
>>>>>>> +
>>>>>>>      static void vfio_realize(PCIDevice *pdev, Error **errp)
>>>>>>>      {
>>>>>>>          VFIOPCIDevice *vdev = VFIO_PCI(pdev);
>>>>>>> @@ -3084,6 +3103,8 @@ static void vfio_realize(PCIDevice *pdev, Error
>>>>>>> **errp)
>>>>>>>          vfio_register_req_notifier(vdev);
>>>>>>>          vfio_setup_resetfn_quirk(vdev);
>>>>>>>      +    pci_setup_pasid_ops(pdev, &vfio_pci_pasid_ops);
>>>>>>> +
>>>>>>>          return;
>>>>>>>        out_deregister:
>>>>>>> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
>>>>>>> index 936d29d150..43696afc15 100644
>>>>>>> --- a/hw/vfio/trace-events
>>>>>>> +++ b/hw/vfio/trace-events
>>>>>>> @@ -120,6 +120,8 @@ vfio_region_sparse_mmap_header(const char *name,
>>>>>>> int index, int nr_areas) "Devic
>>>>>>>      vfio_region_sparse_mmap_entry(int i, unsigned long start,
>>>>>>> unsigned
>>>>>>> long end) "sparse entry %d [0x%lx - 0x%lx]"
>>>>>>>      vfio_get_dev_region(const char *name, int index, uint32_t type,
>>>>>>> uint32_t subtype) "%s index %d, %08x/%0x8"
>>>>>>>      vfio_dma_unmap_overflow_workaround(void) ""
>>>>>>> +vfio_iommu_addr_inv_iotlb(int asid, uint64_t addr, uint64_t size,
>>>>>>> uint64_t nb_granules, bool leaf) "nested IOTLB invalidate asid=%d,
>>>>>>> addr=0x%"PRIx64" granule_size=0x%"PRIx64" nb_granules=0x%"PRIx64"
>>>>>>> leaf=%d"
>>>>>>> +vfio_iommu_asid_inv_iotlb(int asid) "nested IOTLB invalidate
>>>>>>> asid=%d"
>>>>>>>        # platform.c
>>>>>>>      vfio_platform_base_device_init(char *name, int groupid) "%s
>>>>>>> belongs
>>>>>>> to group #%d"
>>>>> .
>>> .
>>
> .