[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v3 03/23] VT-d: limit page table population in domain_pgd_maddr()
I have to admit that I never understood why domain_pgd_maddr() wants to populate all page table levels for DFN 0. I can only assume that despite the comment there what is needed is population just down to the smallest possible nr_pt_levels that the loop later in the function may need to run to. Hence what is needed is the minimum of all possible iommu->nr_pt_levels, to then be passed into addr_to_dma_page_maddr() instead of literal 1. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- v3: New. --- a/xen/drivers/passthrough/vtd/iommu.c +++ b/xen/drivers/passthrough/vtd/iommu.c @@ -55,6 +55,7 @@ bool __read_mostly iommu_snoop = true; #endif static unsigned int __read_mostly nr_iommus; +static unsigned int __read_mostly min_pt_levels = UINT_MAX; static struct iommu_ops vtd_ops; static struct tasklet vtd_fault_tasklet; @@ -482,8 +483,11 @@ static uint64_t domain_pgd_maddr(struct { if ( !hd->arch.vtd.pgd_maddr ) { - /* Ensure we have pagetables allocated down to leaf PTE. */ - addr_to_dma_page_maddr(d, 0, 1, NULL, true); + /* + * Ensure we have pagetables allocated down to the smallest + * level the loop below may need to run to. + */ + addr_to_dma_page_maddr(d, 0, min_pt_levels, NULL, true); if ( !hd->arch.vtd.pgd_maddr ) return 0; @@ -1381,6 +1385,8 @@ int __init iommu_alloc(struct acpi_drhd_ return -ENODEV; } iommu->nr_pt_levels = agaw_to_level(agaw); + if ( min_pt_levels > iommu->nr_pt_levels ) + min_pt_levels = iommu->nr_pt_levels; if ( !ecap_coherent(iommu->ecap) ) vtd_ops.sync_cache = sync_cache;
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