Re: [PATCH 13/15] swiotlb: merge swiotlb-xen initialization into swiotlb
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Date: 2022-03-14 23:11:14
Also in:
linux-arm-kernel, linux-hyperv, linux-iommu, linux-mips, linux-pci, linux-riscv, linux-s390, xen-devel
On 3/14/22 3:31 AM, Christoph Hellwig wrote:
-
static void __init pci_xen_swiotlb_init(void)
{
if (!xen_initial_domain() && !x86_swiotlb_enable)
return;
x86_swiotlb_enable = true;
- xen_swiotlb = true;
- xen_swiotlb_init_early();
+ swiotlb_init_remap(true, x86_swiotlb_flags, xen_swiotlb_fixup);I think we need to have SWIOTLB_ANY set in x86_swiotlb_flags here.
quoted hunk ↗ jump to hunk
dma_ops = &xen_swiotlb_dma_ops; if (IS_ENABLED(CONFIG_PCI)) pci_request_acs();@@ -88,14 +85,16 @@ static void __init pci_xen_swiotlb_init(void) int pci_xen_swiotlb_init_late(void) { - int rc; - - if (xen_swiotlb) + if (dma_ops == &xen_swiotlb_dma_ops) return 0; - rc = xen_swiotlb_init(); - if (rc) - return rc; + /* we can work with the default swiotlb */ + if (!io_tlb_default_mem.nslabs) { + int rc = swiotlb_init_late(swiotlb_size_or_default(), + GFP_KERNEL, xen_swiotlb_fixup);
This may be comment for previous patch but looking at swiotlb_init_late():
retry:
order = get_order(nslabs << IO_TLB_SHIFT);
nslabs = SLABS_PER_PAGE << order;
bytes = nslabs << IO_TLB_SHIFT;
while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
vstart = (void *)__get_free_pages(gfp_mask | __GFP_NOWARN,
order);
if (vstart)
break;
order--;
}
if (!vstart)
return -ENOMEM;
if (remap)
rc = remap(vstart, nslabs);
if (rc) {
free_pages((unsigned long)vstart, order);
/* Min is 2MB */
if (nslabs <= 1024)
return rc;
nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE));
goto retry;
}
if (order != get_order(bytes)) {
pr_warn("only able to allocate %ld MB\n",
(PAGE_SIZE << order) >> 20);
nslabs = SLABS_PER_PAGE << order; <=======
}
rc = swiotlb_late_init_with_tbl(vstart, nslabs);
Notice that we don't do remap() after final update to nslabs. We should.
-boris