Method to test direct memory access (DMA) address capabilities at high address values
A method for detecting a Direct Memory Access (DMA) address capability at high address values when testing PCIe devices is disclosed. The method includes enabling an input/output (I/O) memory management unit (IOMMU); remapping physical addresses to virtual addresses at a high end of an address range; adding a peripheral component interconnect express (PCIe) device; and mapping physical memory addresses to high value memory addresses.
1. A method for detecting a Direct Memory Access (DMA) address capability at high address values when testing PCIe devices, the method comprising:
enabling an input/output (I/O) memory management unit (IOMMU);
adding a peripheral component interconnect express (PCIe) device;
creating by the IOMMU a specified virtual memory address space to the device;
setting the specified virtual address space to high end of address space beyond a memory address range of physical memory;
mapping physical memory addresses to high value memory addresses, wherein a high value memory address is defined as a memory address in an upper limit of an addressing range of a central processing unit (CPU); and
checking direct memory access by the device against the specified virtual memory address space.
2. The method of claim 1 , further comprising monitoring direct memory access (DMA) for accesses to the high value memory addresses.
3. The method of claim 2 , wherein monitoring is repeated until intentionally stopped.
4. The method of claim 1 , comprising adding a memory address for the PCIe device.
5. The method of claim 1 , wherein the IOMMU comprises a virtual memory address space and a physical memory address space.
6. The method of claim 5 , wherein the IOMMU comprises an address mapping function.
7. The method of claim 6 , wherein the address mapping function maps a virtual address of a target device in the virtual memory address space to a physical address in the physical memory address space.
8. The method of claim 1 , comprising allocating contiguous memory addresses using the IOMMU.
9. The method of claim 8 , comprising scanning mapped memory and avoiding address ranges used for a PCIe configuration address space.
10. A non-transitory computer readable medium storing a kernel configuration module which, when executed by a processor of a computing device, detects a Direct Memory Access (DMA) address capability at high address values when testing PCIe devices, said a kernel configuration module comprising sets of instructions for:
enabling an input/output (I/O) memory management unit (IOMMU);
adding a peripheral component interconnect express (PCIe) device;
creating by the IOMMU a specified virtual memory address space to the device;
setting the specified virtual address space to high end of address space beyond a memory address range of physical memory;
mapping physical memory addresses to high value memory addresses, wherein a high value memory address is defined as a memory address in an upper limit of an addressing range of a central processing unit (CPU); and
checking direct memory access by the device against the specified virtual memory address space.
11. The non-transitory computer readable medium of claim 10 , comprising a set of instructions for monitoring direct memory access (DMA) for accesses to the high value memory addresses.
12. The non-transitory computer readable medium of claim 11 , wherein the set of instructions for monitoring direct memory access (DMA) for accesses to the high value memory addresses comprises a set of instructions for repeatedly monitoring direct memory access (DMA) for accesses to the high value memory addresses until intentionally stopped.
13. The non-transitory computer readable medium of claim 10 , comprising a set of instructions for adding a memory address for the PCIe device.
14. The non-transitory computer readable medium of claim 13 , wherein the IOMMU comprises a virtual memory address space, a physical memory address space, and an address mapping function.
15. The non-transitory computer readable medium of claim 14 , wherein the set of instructions for adding a memory address for the PCIe device comprises a set of instructions for mapping the virtual address of the PCIe device in the virtual memory address space to a physical address in the physical memory address space.
16. The non-transitory computer readable medium of claim 15 , wherein the set of instructions for mapping comprises a set of instructions for using the address mapping function in the IOMMU.
17. The non-transitory computer readable medium of claim 10 , comprising a set of instructions for allocating contiguous memory addresses using the IOMMU.
18. The non-transitory computer readable medium of claim 17 , comprising a set of instructions for scanning mapped memory and avoiding address ranges used for a PCIe configuration address space.
19. A method for detecting a Direct Memory Access (DMA) address capability at high address values when testing PCIe devices, the method comprising:
enabling an input/output (I/O) memory management unit (IOMMU);
adding a peripheral component interconnect express (PCIe) device;
assigning by the IOMMU a virtual memory address space to the device;
creating by the IOMMU a specified virtual memory address space to the device;
setting the specified virtual address space to high end of address space beyond a memory address range of physical memory;
mapping physical memory addresses to high value memory addresses, wherein a high value memory address is defined as a memory address in an upper limit of an addressing range of a central processing unit (CPU); and
verifying direct memory access addressing capability of the device at the high end of the address range.