Hello Wei Hu,
The patch 3a6fb6c4255c: "video: hyperv: hyperv_fb: Use physical
memory for fb on HyperV Gen 1 VMs." from Dec 9, 2019, leads to the
following static checker warning:
drivers/video/fbdev/hyperv_fb.c:991 hvfb_get_phymem()
error: 'vmem' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/video/fbdev/hyperv_fb.c
960 static phys_addr_t hvfb_get_phymem(struct hv_device *hdev,
961 unsigned int request_size)
962 {
963 struct page *page = NULL;
964 dma_addr_t dma_handle;
965 void *vmem;
966 phys_addr_t paddr = 0;
967 unsigned int order = get_order(request_size);
968
969 if (request_size == 0)
970 return -1;
971
972 if (order < MAX_ORDER) {
973 /* Call alloc_pages if the size is less than 2^MAX_ORDER */
974 page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
975 if (!page)
976 return -1;
977
978 paddr = (page_to_pfn(page) << PAGE_SHIFT);
979 } else {
980 /* Allocate from CMA */
981 hdev->device.coherent_dma_mask = DMA_BIT_MASK(64);
982
983 vmem = dma_alloc_coherent(&hdev->device,
984 round_up(request_size, PAGE_SIZE),
985 &dma_handle,
986 GFP_KERNEL | __GFP_NOWARN);
987
988 if (!vmem)
989 return -1;
990
991 paddr = virt_to_phys(vmem);
Pretty straight forward that the static checker is right but I can't
give you any hints how to fix it.
992 }
993
994 return paddr;
995 }
regards,
dan carpenter
