On Sun, 29 Mar 2020 15:20:55 +0800 Lu Baolu <[email protected]> wrote:
> On 2020/3/27 19:53, Tian, Kevin wrote: > >> From: Jacob Pan <[email protected]> > >> Sent: Saturday, March 21, 2020 7:28 AM > >> > >> Signed-off-by: Jacob Pan <[email protected]> > > > > could you elaborate in which scenario this helper function is > > required? > > I added below commit message: > > An Intel iommu domain uses 5-level page table by default. If the > iommu that the domain tries to attach supports less page levels, > the top level page tables should be skipped. Add a helper to do > this so that it could be used in other places. > Thanks Baolu, I will also add this to my v11, it might save you some time :) > Best regards, > baolu > > > > >> --- > >> drivers/iommu/intel-pasid.c | 22 ++++++++++++++++++++++ > >> 1 file changed, 22 insertions(+) > >> > >> diff --git a/drivers/iommu/intel-pasid.c > >> b/drivers/iommu/intel-pasid.c index 22b30f10b396..191508c7c03e > >> 100644 --- a/drivers/iommu/intel-pasid.c > >> +++ b/drivers/iommu/intel-pasid.c > >> @@ -500,6 +500,28 @@ int intel_pasid_setup_first_level(struct > >> intel_iommu *iommu, > >> } > >> > >> /* > >> + * Skip top levels of page tables for iommu which has less agaw > >> + * than default. Unnecessary for PT mode. > >> + */ > >> +static inline int iommu_skip_agaw(struct dmar_domain *domain, > >> + struct intel_iommu *iommu, > >> + struct dma_pte **pgd) > >> +{ > >> + int agaw; > >> + > >> + for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) { > >> + *pgd = phys_to_virt(dma_pte_addr(*pgd)); > >> + if (!dma_pte_present(*pgd)) { > >> + return -EINVAL; > >> + } > >> + } > >> + pr_debug_ratelimited("%s: pgd: %llx, agaw %d d_agaw %d\n", > >> __func__, (u64)*pgd, > >> + iommu->agaw, domain->agaw); > >> + > >> + return agaw; > >> +} > >> + > >> +/* > >> * Set up the scalable mode pasid entry for second only > >> translation type. */ > >> int intel_pasid_setup_second_level(struct intel_iommu *iommu, > >> -- > >> 2.7.4 > > [Jacob Pan] _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
