On 8/20/2021 2:11 AM, Michael Kelley wrote:
} + +/* + * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM. + */ +void *hv_map_memory(void *addr, unsigned long size) +{ + unsigned long *pfns = kcalloc(size / HV_HYP_PAGE_SIZE, + sizeof(unsigned long), GFP_KERNEL); + void *vaddr; + int i; + + if (!pfns) + return NULL; + + for (i = 0; i < size / HV_HYP_PAGE_SIZE; i++) + pfns[i] = virt_to_hvpfn(addr + i * HV_HYP_PAGE_SIZE) + + (ms_hyperv.shared_gpa_boundary >> HV_HYP_PAGE_SHIFT); + + vaddr = vmap_pfn(pfns, size / HV_HYP_PAGE_SIZE, PAGE_KERNEL_IO); + kfree(pfns); + + return vaddr; +}This function is manipulating page tables in the guest VM. It is not involved in communicating with Hyper-V, or passing PFNs to Hyper-V. The pfn array contains guest PFNs, not Hyper-V PFNs. So it should use PAGE_SIZE instead of HV_HYP_PAGE_SIZE, and similarly PAGE_SHIFT and virt_to_pfn(). If this code were ever to run on ARM64 in the future with PAGE_SIZE other than 4 Kbytes, the use of PAGE_SIZE is correct choice.
OK. Will update with PAGE_SIZE.
+void __init hyperv_iommu_swiotlb_init(void) +{ + unsigned long bytes; + + /* + * Allocate Hyper-V swiotlb bounce buffer at early place + * to reserve large contiguous memory. + */ + hyperv_io_tlb_size = 256 * 1024 * 1024;A hard coded size here seems problematic. The memory size of Isolated VMs can vary by orders of magnitude. I see that xen_swiotlb_init() uses swiotlb_size_or_default(), which at least pays attention to the value specified on the kernel boot line. Another example is sev_setup_arch(), which in the native case sets the size to 6% of main memory, with a max of 1 Gbyte. This is the case that's closer to Isolated VMs, so doing something similar could be a good approach.
Yes, agree. It's better to keep bounce buffer size with AMD SEV.
