RE: [PATCH v3 12/17] intel_iommu: Add support for PASID-based device IOTLB invalidation

[Duan, Zhenzhong]

>-----Original Message-----
>From: Duan, Zhenzhong
>Subject: RE: [PATCH v3 12/17] intel_iommu: Add support for PASID-based
>device IOTLB invalidation
>
>
>
>>-----Original Message-----
>>From: Jason Wang <jasowang@redhat.com>
>>Subject: Re: [PATCH v3 12/17] intel_iommu: Add support for PASID-based
>>device IOTLB invalidation
>>
>>On Wed, Sep 11, 2024 at 1:27 PM Zhenzhong Duan
>><zhenzhong.duan@intel.com> wrote:
>>>
>>> From: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
>>>
>>> Signed-off-by: Clément Mathieu--Drif <clement.mathieu--
>drif@eviden.com>
>>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> ---
>>>  hw/i386/intel_iommu_internal.h | 11 ++++++++
>>>  hw/i386/intel_iommu.c          | 50
>>++++++++++++++++++++++++++++++++++
>>>  2 files changed, 61 insertions(+)
>>>
>>> diff --git a/hw/i386/intel_iommu_internal.h
>>b/hw/i386/intel_iommu_internal.h
>>> index 4f2c3a9350..52bdbf3bc5 100644
>>> --- a/hw/i386/intel_iommu_internal.h
>>> +++ b/hw/i386/intel_iommu_internal.h
>>> @@ -375,6 +375,7 @@ typedef union VTDInvDesc VTDInvDesc;
>>>  #define VTD_INV_DESC_WAIT               0x5 /* Invalidation Wait
>Descriptor
>>*/
>>>  #define VTD_INV_DESC_PIOTLB             0x6 /* PASID-IOTLB Invalidate
>Desc
>>*/
>>>  #define VTD_INV_DESC_PC                 0x7 /* PASID-cache Invalidate Desc
>*/
>>> +#define VTD_INV_DESC_DEV_PIOTLB         0x8 /* PASID-based-DIOTLB
>>inv_desc*/
>>>  #define VTD_INV_DESC_NONE               0   /* Not an Invalidate Descriptor
>>*/
>>>
>>>  /* Masks for Invalidation Wait Descriptor*/
>>> @@ -413,6 +414,16 @@ typedef union VTDInvDesc VTDInvDesc;
>>>  #define VTD_INV_DESC_DEVICE_IOTLB_RSVD_HI 0xffeULL
>>>  #define VTD_INV_DESC_DEVICE_IOTLB_RSVD_LO 0xffff0000ffe0fff8
>>>
>>> +/* Mask for PASID Device IOTLB Invalidate Descriptor */
>>> +#define VTD_INV_DESC_PASID_DEVICE_IOTLB_ADDR(val) ((val) & \
>>> +                                                   0xfffffffffffff000ULL)
>>> +#define VTD_INV_DESC_PASID_DEVICE_IOTLB_SIZE(val) ((val >> 11) &
>0x1)
>>> +#define VTD_INV_DESC_PASID_DEVICE_IOTLB_GLOBAL(val) ((val) & 0x1)
>>> +#define VTD_INV_DESC_PASID_DEVICE_IOTLB_SID(val) (((val) >> 16) &
>>0xffffULL)
>>> +#define VTD_INV_DESC_PASID_DEVICE_IOTLB_PASID(val) ((val >> 32) &
>>0xfffffULL)
>>> +#define VTD_INV_DESC_PASID_DEVICE_IOTLB_RSVD_HI 0x7feULL
>>> +#define VTD_INV_DESC_PASID_DEVICE_IOTLB_RSVD_LO
>>0xfff000000000f000ULL
>>> +
>>>  /* Rsvd field masks for spte */
>>>  #define VTD_SPTE_SNP 0x800ULL
>>>
>>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>>> index d28c862598..4cf56924e1 100644
>>> --- a/hw/i386/intel_iommu.c
>>> +++ b/hw/i386/intel_iommu.c
>>> @@ -3017,6 +3017,49 @@ static void
>>do_invalidate_device_tlb(VTDAddressSpace *vtd_dev_as,
>>>      memory_region_notify_iommu(&vtd_dev_as->iommu, 0, event);
>>>  }
>>>
>>> +static bool vtd_process_device_piotlb_desc(IntelIOMMUState *s,
>>> +                                           VTDInvDesc *inv_desc)
>>> +{
>>> +    uint16_t sid;
>>> +    VTDAddressSpace *vtd_dev_as;
>>> +    bool size;
>>> +    bool global;
>>> +    hwaddr addr;
>>> +    uint32_t pasid;
>>> +
>>> +    if ((inv_desc->hi & VTD_INV_DESC_PASID_DEVICE_IOTLB_RSVD_HI) ||
>>> +         (inv_desc->lo & VTD_INV_DESC_PASID_DEVICE_IOTLB_RSVD_LO)) {
>>> +        error_report_once("%s: invalid pasid-based dev iotlb inv desc:"
>>> +                          "hi=%"PRIx64 "(reserved nonzero)",
>>> +                          __func__, inv_desc->hi);
>>> +        return false;
>>> +    }
>>> +
>>> +    global = VTD_INV_DESC_PASID_DEVICE_IOTLB_GLOBAL(inv_desc->hi);
>>> +    size = VTD_INV_DESC_PASID_DEVICE_IOTLB_SIZE(inv_desc->hi);
>>> +    addr = VTD_INV_DESC_PASID_DEVICE_IOTLB_ADDR(inv_desc->hi);
>>> +    sid = VTD_INV_DESC_PASID_DEVICE_IOTLB_SID(inv_desc->lo);
>>> +    if (global) {
>>> +        QLIST_FOREACH(vtd_dev_as, &s->vtd_as_with_notifiers, next) {
>>> +            if ((vtd_dev_as->pasid != PCI_NO_PASID) &&
>>> +                (PCI_BUILD_BDF(pci_bus_num(vtd_dev_as->bus),
>>> +                                           vtd_dev_as->devfn) == sid)) {
>>> +                do_invalidate_device_tlb(vtd_dev_as, size, addr);
>>> +            }
>>> +        }
>>> +    } else {
>>> +        pasid = VTD_INV_DESC_PASID_DEVICE_IOTLB_PASID(inv_desc->lo);
>>> +        vtd_dev_as = vtd_get_as_by_sid_and_pasid(s, sid, pasid);
>>> +        if (!vtd_dev_as) {
>>> +            return true;
>>> +        }
>>> +
>>> +        do_invalidate_device_tlb(vtd_dev_as, size, addr);
>>
>>Question:
>>
>>I wonder if current vhost (which has a device IOTLB abstraction via
>>virtio-pci) can work with this (PASID based IOTLB invalidation)
>
>Currently, it depends on if caching-mode is on. If it's off, vhost works. E.g.:
>
>-device intel-iommu,caching-mode=off,dma-drain=on,device-iotlb=on,x-
>scalable-mode=on
>-netdev tap,id=tap0,vhost=on,script=/etc/qemu-ifup
>-device virtio-net-pci,netdev=tap0,bus=root0,iommu_platform=on,ats=on

Sorry, typo error on scalable mode parameter, should be:

-device 
intel-iommu,caching-mode=off,dma-drain=on,device-iotlb=on,x-scalable-mode=modern
-netdev tap,id=tap0,vhost=on,script=/etc/qemu-ifup
-device virtio-net-pci,netdev=tap0,bus=root0,iommu_platform=on,ats=on

Thanks
Zhenzhong

>
>It doesn't work currently when caching-mode is on.
>Reason is linux kernel has an optimization to send only piotlb invalidation,
>no device-piotlb invalidation is sent. But I heard from Yi the optimization
>will be dropped, then it will work too when caching-mode is on.
>
>Thanks
>Zhenzhong