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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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fc2341df9e
If a PV guest is booted the native SWIOTLB should not be turned on. It does not help us (we don't have any PCI devices) and it eats 64MB of good memory. In the case of PV guests with PCI devices we need the Xen-SWIOTLB one. [v1: Rewrite comment per Stefano's suggestion] Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
83 lines
2.2 KiB
C
83 lines
2.2 KiB
C
/* Glue code to lib/swiotlb-xen.c */
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#include <linux/dma-mapping.h>
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#include <linux/pci.h>
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#include <xen/swiotlb-xen.h>
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#include <asm/xen/hypervisor.h>
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#include <xen/xen.h>
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#include <asm/iommu_table.h>
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#ifdef CONFIG_X86_64
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#include <asm/iommu.h>
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#include <asm/dma.h>
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#endif
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int xen_swiotlb __read_mostly;
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static struct dma_map_ops xen_swiotlb_dma_ops = {
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.mapping_error = xen_swiotlb_dma_mapping_error,
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.alloc = xen_swiotlb_alloc_coherent,
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.free = xen_swiotlb_free_coherent,
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.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
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.sync_single_for_device = xen_swiotlb_sync_single_for_device,
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.sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
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.sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
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.map_sg = xen_swiotlb_map_sg_attrs,
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.unmap_sg = xen_swiotlb_unmap_sg_attrs,
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.map_page = xen_swiotlb_map_page,
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.unmap_page = xen_swiotlb_unmap_page,
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.dma_supported = xen_swiotlb_dma_supported,
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};
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/*
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* pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
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*
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* This returns non-zero if we are forced to use xen_swiotlb (by the boot
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* option).
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*/
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int __init pci_xen_swiotlb_detect(void)
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{
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if (!xen_pv_domain())
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return 0;
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/* If running as PV guest, either iommu=soft, or swiotlb=force will
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* activate this IOMMU. If running as PV privileged, activate it
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* irregardless.
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*/
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if ((xen_initial_domain() || swiotlb || swiotlb_force))
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xen_swiotlb = 1;
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/* If we are running under Xen, we MUST disable the native SWIOTLB.
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* Don't worry about swiotlb_force flag activating the native, as
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* the 'swiotlb' flag is the only one turning it on. */
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swiotlb = 0;
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#ifdef CONFIG_X86_64
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/* pci_swiotlb_detect_4gb turns on native SWIOTLB if no_iommu == 0
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* (so no iommu=X command line over-writes).
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* Considering that PV guests do not want the *native SWIOTLB* but
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* only Xen SWIOTLB it is not useful to us so set no_iommu=1 here.
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*/
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if (max_pfn > MAX_DMA32_PFN)
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no_iommu = 1;
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#endif
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return xen_swiotlb;
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}
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void __init pci_xen_swiotlb_init(void)
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{
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if (xen_swiotlb) {
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xen_swiotlb_init(1);
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dma_ops = &xen_swiotlb_dma_ops;
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/* Make sure ACS will be enabled */
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pci_request_acs();
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}
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}
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IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
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0,
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pci_xen_swiotlb_init,
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0);
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