On Tue, May 21, 2024 at 6:25 PM Duan, Zhenzhong
<zhenzhong.d...@intel.com> wrote:
>
>
>
> >-----Original Message-----
> >From: Jason Wang <jasow...@redhat.com>
> >Subject: Re: [PATCH] intel_iommu: Use the latest fault reasons defined by
> >spec
> >
> >On Mon, May 20, 2024 at 12:15 PM Liu, Yi L <yi.l....@intel.com> wrote:
> >>
> >> > From: Duan, Zhenzhong <zhenzhong.d...@intel.com>
> >> > Sent: Monday, May 20, 2024 11:41 AM
> >> >
> >> >
> >> >
> >> > >-----Original Message-----
> >> > >From: Jason Wang <jasow...@redhat.com>
> >> > >Sent: Monday, May 20, 2024 8:44 AM
> >> > >To: Duan, Zhenzhong <zhenzhong.d...@intel.com>
> >> > >Cc: qemu-devel@nongnu.org; Liu, Yi L <yi.l....@intel.com>; Peng, Chao
> >P
> >> > ><chao.p.p...@intel.com>; Yu Zhang <yu.c.zh...@linux.intel.com>;
> >Michael
> >> > >S. Tsirkin <m...@redhat.com>; Paolo Bonzini <pbonz...@redhat.com>;
> >> > >Richard Henderson <richard.hender...@linaro.org>; Eduardo Habkost
> >> > ><edua...@habkost.net>; Marcel Apfelbaum
> ><marcel.apfelb...@gmail.com>
> >> > >Subject: Re: [PATCH] intel_iommu: Use the latest fault reasons defined
> >by
> >> > >spec
> >> > >
> >> > >On Fri, May 17, 2024 at 6:26 PM Zhenzhong Duan
> >> > ><zhenzhong.d...@intel.com> wrote:
> >> > >>
> >> > >> From: Yu Zhang <yu.c.zh...@linux.intel.com>
> >> > >>
> >> > >> Currently we use only VTD_FR_PASID_TABLE_INV as fault reason.
> >> > >> Update with more detailed fault reasons listed in VT-d spec 7.2.3.
> >> > >>
> >> > >> Signed-off-by: Yu Zhang <yu.c.zh...@linux.intel.com>
> >> > >> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
> >> > >> ---
> >> > >
> >> > >I wonder if this could be noticed by the guest or not. If yes should
> >> > >we consider starting to add thing like version to vtd emulation code?
> >> >
> >> > Kernel only dumps the reason like below:
> >> >
> >> > DMAR: [DMA Write NO_PASID] Request device [20:00.0] fault addr
> >0x1234600000
> >> > [fault reason 0x71] SM: Present bit in first-level paging entry is clear
> >>
> >> Yes, guest kernel would notice it as the fault would be injected to vm.
> >>
> >> > Maybe bump 1.0 -> 1.1?
> >> > My understanding version number is only informational and is far from
> >> > accurate to mark if a feature supported. Driver should check cap/ecap
> >> > bits instead.
> >>
> >> Should the version ID here be aligned with VT-d spec?
> >
> >Probably, this might be something that could be noticed by the
> >management to migration compatibility.
>
> Could you elaborate what we need to do for migration compatibility?
> I see version is already exported so libvirt can query it, see:
>
> DEFINE_PROP_UINT32("version", IntelIOMMUState, version, 0),
It is the Qemu command line parameters not the version of the vmstate.
For example -device intel-iommu,version=3.0
Qemu then knows it should behave as 3.0.
Thanks
>
> Thanks
> Zhenzhong
>
> >
> >> If yes, it should
> >> be 3.0 as the scalable mode was introduced in spec 3.0. And the fault
> >> code was redefined together with the introduction of this translation
> >> mode. Below is the a snippet from the change log of VT-d spec.
> >>
> >> June 2018 3.0
> >> • Removed all text related to Extended-Mode.
> >> • Added support for scalable-mode translation for DMA Remapping, that
> >enables PASIDgranular first-level, second-level, nested and pass-through
> >translation functions.
> >> • Widen invalidation queue descriptors and page request queue
> >descriptors from 128 bits
> >> to 256 bits and redefined page-request and page-response descriptors.
> >> • Listed all fault conditions in a unified table and described DMA
> >Remapping hardware
> >> behavior under each condition. Assigned new code for each fault condition
> >in scalablemode operation.
> >> • Added support for Accessed/Dirty (A/D) bits in second-level translation.
> >> • Added support for submitting commands and receiving response from
> >virtual DMA
> >> Remapping hardware.
> >> • Added a table on snooping behavior and memory type of hardware
> >access to various
> >> remapping structures as appendix.
> >> • Move Page Request Overflow (PRO) fault reporting from Fault Status
> >register
> >> (FSTS_REG) to Page Request Status register (PRS_REG).
> >>
> >> Regards.
> >> Yi Liu
> >
> >Thanks
>
