[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH, RFC] x86/iommu: don't map RAM holes above 4G
Matching the comment in iommu_set_dom0_mapping(), map only actual RAM from the address range starting at 4G. It's not clear though whether that comment is actually correct (which is why I'm sending this as RFC), but it is certain that on systems with sparse physical memory map we're currently wasting a potentially significant amount of memory for setting up IOMMU page tables that will never be used. The main question is what happens for MMIO ranges living above 4G. Of course, the same issue would currently exist for any such ranges sitting beyon the end of RAM. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx> --- a/xen/drivers/passthrough/amd/pci_amd_iommu.c +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c @@ -230,8 +230,16 @@ static void __init amd_iommu_dom0_init(s if ( !iommu_passthrough && !need_iommu(d) ) { /* Set up 1:1 page table for dom0 */ - for ( i = 0; i < max_page; i++ ) - amd_iommu_map_page(d, i, i, IOMMUF_readable|IOMMUF_writable); + for ( i = 0; i < max_pdx; i++ ) + { + unsigned long pfn = pdx_to_pfn(i); + + /* + * XXX Should we really map all non-RAM (above 4G)? Minimally + * a pfn_valid() check would seem desirable here. + */ + amd_iommu_map_page(d, pfn, pfn, IOMMUF_readable|IOMMUF_writable); + } } amd_iommu_setup_dom0_devices(d); --- a/xen/drivers/passthrough/vtd/x86/vtd.c +++ b/xen/drivers/passthrough/vtd/x86/vtd.c @@ -129,14 +129,14 @@ void hvm_dpci_isairq_eoi(struct domain * void __init iommu_set_dom0_mapping(struct domain *d) { - u64 i, j, tmp, max_pfn; + unsigned long i, j, tmp, top; extern int xen_in_range(unsigned long mfn); BUG_ON(d->domain_id != 0); - max_pfn = max_t(u64, max_page, 0x100000000ull >> PAGE_SHIFT); + top = max(max_pdx, pfn_to_pdx(0xffffffffUL >> PAGE_SHIFT) + 1); - for ( i = 0; i < max_pfn; i++ ) + for ( i = 0; i < top; i++ ) { /* * Set up 1:1 mapping for dom0. Default to use only conventional RAM @@ -144,18 +144,23 @@ void __init iommu_set_dom0_mapping(struc * inclusive mapping maps in everything below 4GB except unusable * ranges. */ - if ( !page_is_ram_type(i, RAM_TYPE_CONVENTIONAL) && - (!iommu_inclusive_mapping || - page_is_ram_type(i, RAM_TYPE_UNUSABLE)) ) + unsigned long pfn = pdx_to_pfn(i); + + if ( pfn > (0xffffffffUL >> PAGE_SHIFT) ? + (!mfn_valid(pfn) || + !page_is_ram_type(pfn, RAM_TYPE_CONVENTIONAL)) : + iommu_inclusive_mapping ? + page_is_ram_type(pfn, RAM_TYPE_UNUSABLE) : + !page_is_ram_type(pfn, RAM_TYPE_CONVENTIONAL) ) continue; /* Exclude Xen bits */ - if ( xen_in_range(i) ) + if ( xen_in_range(pfn) ) continue; tmp = 1 << (PAGE_SHIFT - PAGE_SHIFT_4K); for ( j = 0; j < tmp; j++ ) - iommu_map_page(d, (i*tmp+j), (i*tmp+j), + iommu_map_page(d, pfn * tmp + j, pfn * tmp + j, IOMMUF_readable|IOMMUF_writable); if (!(i & (0xfffff >> (PAGE_SHIFT - PAGE_SHIFT_4K)))) Attachment:
iommu-dom0-holes.patch _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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