pci-swiotlb-xen.c

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/* Glue code to lib/swiotlb-xen.c */

#include <linux/dma-mapping.h>
#include <linux/pci.h>
#include <xen/swiotlb-xen.h>

#include <asm/xen/hypervisor.h>
#include <xen/xen.h>
#include <asm/iommu_table.h>


#include <asm/xen/swiotlb-xen.h>
#ifdef CONFIG_X86_64
#include <asm/iommu.h>
#include <asm/dma.h>
#endif
#include <linux/export.h>

int xen_swiotlb __read_mostly;

static struct dma_map_ops xen_swiotlb_dma_ops = {
    .mapping_error = xen_swiotlb_dma_mapping_error,
    .alloc = xen_swiotlb_alloc_coherent,
    .free = xen_swiotlb_free_coherent,
    .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
    .sync_single_for_device = xen_swiotlb_sync_single_for_device,
    .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
    .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
    .map_sg = xen_swiotlb_map_sg_attrs,
    .unmap_sg = xen_swiotlb_unmap_sg_attrs,
    .map_page = xen_swiotlb_map_page,
    .unmap_page = xen_swiotlb_unmap_page,
    .dma_supported = xen_swiotlb_dma_supported,
};

/*
 * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
 *
 * This returns non-zero if we are forced to use xen_swiotlb (by the boot
 * option).
 */
int __init pci_xen_swiotlb_detect(void)
{

    if (!xen_pv_domain())
        return 0;

    /* If running as PV guest, either iommu=soft, or swiotlb=force will
     * activate this IOMMU. If running as PV privileged, activate it
     * irregardless.
     */
    if ((xen_initial_domain() || swiotlb || swiotlb_force))
        xen_swiotlb = 1;

    /* If we are running under Xen, we MUST disable the native SWIOTLB.
     * Don't worry about swiotlb_force flag activating the native, as
     * the 'swiotlb' flag is the only one turning it on. */
    swiotlb = 0;

#ifdef CONFIG_X86_64
    /* pci_swiotlb_detect_4gb turns on native SWIOTLB if no_iommu == 0
     * (so no iommu=X command line over-writes).
     * Considering that PV guests do not want the *native SWIOTLB* but
     * only Xen SWIOTLB it is not useful to us so set no_iommu=1 here.
     */
    if (max_pfn > MAX_DMA32_PFN)
        no_iommu = 1;
#endif
    return xen_swiotlb;
}

void __init pci_xen_swiotlb_init(void)
{
    if (xen_swiotlb) {
        xen_swiotlb_init(1, true /* early */);
        dma_ops = &xen_swiotlb_dma_ops;

        /* Make sure ACS will be enabled */
        pci_request_acs();
    }
}

int pci_xen_swiotlb_init_late(void)
{
    int rc;

    if (xen_swiotlb)
        return 0;

    rc = xen_swiotlb_init(1, false /* late */);
    if (rc)
        return rc;

    dma_ops = &xen_swiotlb_dma_ops;
    /* Make sure ACS will be enabled */
    pci_request_acs();

    return 0;
}
EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);

IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
          NULL,
          pci_xen_swiotlb_init,
          NULL);