[Xen-devel] [PATCH] xen/swiotlb: don't initialize swiotlb twice on arm64

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Stefano Stabellini <stefanos@xxxxxxxxxx>

On arm64 swiotlb is already initialized by mem_init. We don't want to
initialize it twice, the memory is already allocated. Detect this
condition in swiotlb-xen and skip the second initialization.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>

---

There are other issues which I found recently affecting the swiotlb on
arm64 -- I'll send the other patches separately.

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 877baf2..8fcda2bf4 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -206,6 +206,7 @@ int __ref xen_swiotlb_init(int verbose, bool early)
        int rc = -ENOMEM;
        enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
        unsigned int repeat = 3;
+       bool pre_initialized = false;
 
        xen_io_tlb_nslabs = swiotlb_nr_tbl();
 retry:
@@ -214,7 +215,10 @@ int __ref xen_swiotlb_init(int verbose, bool early)
        /*
         * Get IO TLB memory from any location.
         */
-       if (early) {
+       if (io_tlb_start != 0) {
+               xen_io_tlb_start = phys_to_virt(io_tlb_start);
+               pre_initialized = true;
+       } else if (early) {
                xen_io_tlb_start = memblock_alloc(PAGE_ALIGN(bytes),
                                                  PAGE_SIZE);
                if (!xen_io_tlb_start)
@@ -264,7 +268,7 @@ int __ref xen_swiotlb_init(int verbose, bool early)
                         verbose))
                        panic("Cannot allocate SWIOTLB buffer");
                rc = 0;
-       } else
+       } else if (!pre_initialized)
                rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, 
xen_io_tlb_nslabs);
 
        if (!rc)

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