Messages in this thread | | | Date | Tue, 19 Nov 2019 09:12:41 -0800 | From | Jacob Pan <> | Subject | Re: [PATCH v2 04/10] iommu/vt-d: Match CPU and IOMMU paging mode |
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On Tue, 19 Nov 2019 09:04:10 +0100 Auger Eric <eric.auger@redhat.com> wrote:
> Hi Lu, Jacob, > > On 11/19/19 4:06 AM, Lu Baolu wrote: > > Hi Eric and Jacob, > > > > On 11/19/19 5:52 AM, Jacob Pan wrote: > >> On Mon, 18 Nov 2019 21:55:03 +0100 > >> Auger Eric <eric.auger@redhat.com> wrote: > >> > >>> Hi Jacob, > >>> > >>> On 11/18/19 8:42 PM, Jacob Pan wrote: > >>>> When setting up first level page tables for sharing with CPU, we > >>>> need to ensure IOMMU can support no less than the levels > >>>> supported by the CPU. > >>>> It is not adequate, as in the current code, to set up 5-level > >>>> paging in PASID entry First Level Paging Mode(FLPM) solely based > >>>> on CPU. > >>>> > >>>> Fixes: 437f35e1cd4c8 ("iommu/vt-d: Add first level page table > >>>> interface") > >>>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> > >>>> Acked-by: Lu Baolu <baolu.lu@linux.intel.com> > >>>> --- > >>>> drivers/iommu/intel-pasid.c | 12 ++++++++++-- > >>>> 1 file changed, 10 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/drivers/iommu/intel-pasid.c > >>>> b/drivers/iommu/intel-pasid.c index 040a445be300..e7cb0b8a7332 > >>>> 100644 --- a/drivers/iommu/intel-pasid.c > >>>> +++ b/drivers/iommu/intel-pasid.c > >>>> @@ -499,8 +499,16 @@ int intel_pasid_setup_first_level(struct > >>>> intel_iommu *iommu, } > >>>> #ifdef CONFIG_X86 > >>>> - if (cpu_feature_enabled(X86_FEATURE_LA57)) > >>>> - pasid_set_flpm(pte, 1); > >>>> + /* Both CPU and IOMMU paging mode need to match */ > >>>> + if (cpu_feature_enabled(X86_FEATURE_LA57)) { > >>>> + if (cap_5lp_support(iommu->cap)) { > >>>> + pasid_set_flpm(pte, 1); > >>>> + } else { > >>>> + pr_err("VT-d has no 5-level paging support > >>>> for CPU\n"); > >>>> + pasid_clear_entry(pte); > >>>> + return -EINVAL; > >>> Can it happen? If I am not wrong intel_pasid_setup_first_level() > >>> only seems to be called from intel_svm_bind_mm which now checks > >>> the SVM_CAPABLE flag. > >>> > >> You are right, this check is not needed any more. I will drop the > >> patch. > >>> Thanks > > > > I'd suggest to keep this. This helper is not only for svm, although > > currently svm is the only caller. For first level pasid setup, let's > > set an assumption that hardware should never report mismatching > > paging modes, this is helpful especially when running vIOMMU in VM > > guests. > > OK. So maybe just add the rationale in the commit message? > OK. will do. I thought about Baolu's point as well then I thought the other use of first level map for replacing today's VFIO second level map in the guest, but that will have a different helper. Anyway, I will keep this one then.
Thanks you both!
> Thanks > > Eric > > > > Best regards, > > baolu > > >
[Jacob Pan]
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