On 12/4/2021 3:17 AM, Michael Kelley (LINUX) wrote:

quoted

+static void __init hyperv_iommu_swiotlb_init(void)
+{
+	unsigned long hyperv_io_tlb_size;
+	void *hyperv_io_tlb_start;
+
+	/*
+	 * Allocate Hyper-V swiotlb bounce buffer at early place
+	 * to reserve large contiguous memory.
+	 */
+	hyperv_io_tlb_size = swiotlb_size_or_default();
+	hyperv_io_tlb_start = memblock_alloc(hyperv_io_tlb_size, PAGE_SIZE);
+
+	if (!hyperv_io_tlb_start)
+		pr_warn("Fail to allocate Hyper-V swiotlb buffer.\n");

In the error case, won't swiotlb_init_with_tlb() end up panic'ing when
it tries to zero out the memory?   The only real choice here is to
return immediately after printing the message, and not call
swiotlb_init_with_tlb().

Yes, agree. Will update.