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

[Jason Wang]

On Fri, Sep 27, 2024 at 3:18 PM Duan, Zhenzhong
<zhenzhong.duan@intel.com> wrote:
>
>
>
> >-----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
>
> 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.

Great, if possible please copy me when sending those fixes.

Thanks

>
> Thanks
> Zhenzhong