memoryvirtualization-vmware-e6998-virtual-資料下載頁(yè)
【導(dǎo)讀】Lecture3. ScottDevine. VMware,Inc.Outline. Background. –EmulatedTLB. –ShadowPageTables. PageProtection. –MemoryTracing. –HidingtheMonitor. –NestedPageTables. CPU. MMU. Memory. Controller. LocalBus. Interface. High-Speed. I/OBus. LAN. Low-Speed. I/OBus. USBCD-ROM. 04GB. Physical. Frame. Buffer. 04GB. CurrentProcess. 04GB. Physical. Frame. Buffer. 04GB. 04GB. CurrentProcess. 04GB. Physical. Frame. Buffer. –Worksinfixed-sizedpages. –PageProtection. Controlregisters. –PageTablelocation. –CurrentASID. –Alignmentchecking. TypesofMMUs. x86,x86-64,ARM,IBMSystem/370,PowerPC. ArchitectedTLBs. MIPS,SPARC,Alpha. Segmentation/NoMMU. Low-endARMs,micro-controllers. Process. PageTable. 12. 2. 3. 45. TLB. OperatingSystem’s. PageFaultHandler. 04GB. 04GB. Physical. Virtual. ROM. Virtual. Devices. Virtual. Frame. Buffer. 04GB. 04GB. Physical. Virtual. ROM. Virtual. Devices. Virtual. Frame. Buffer. 04GB. Machine. Frame. Buffer. Outline. Background. –EmulatedTLB. –ShadowPageTables. PageProtection. –MemoryTracing. –HidingtheMonitor. –NestedPageTables. w/EmulatedTLB. 04GB. 0. 0. GuestPageTable. VMMPhysMap. 4GB. 4GB. Em. ula. ted. TL. B. Pa. ge. Ta. ble. w/EmulatedTLB. EmulatedTLB. 12. 2. 3. 45. 3. 6. TLB. A. Performance. ShadowPageTables. Guest. PageTable. Shadow. PageTable. Guest. PageTable. Guest. PageTable. Shadow. PageTable. Shadow. PageTable. VirtualCR3. RealCR3
【正文】 ngles guest and monitor memory accesses – Need to distinguish these accesses – Monitor accesses have full privileges – Guest accesses have lesser privileges ? On x86 can use segmentation – Monitor lives in high memory – Guest segments truncated to allow no access to monitor – Binary translator uses guest segments for guest accesses and monitor segments for monitor accesses Outline ? Background ? Virtualization Techniques – Emulated TLB – Shadow Page Tables ? Page Protection – Memory Tracing – Hiding the Monitor ? Hardwaresupported Memory Virtualization – Nested Page Tables Virtualized Address Spaces w/ Nested Page Tables Virtual Address Space 0 4GB Physical Address Space 0 Machine Address Space 0 Guest Page Table VMM PhysMap 4GB 4GB Virtualized Address Translation w/ Nested Page Tables Virtual Address Machine Address Guest Page Table PhysMap By VMM 1 2 TLB 3 2 3 Issues with Nested Page Tables ? Positives – Simplifies monitor design – No need for page protection calculus ? Negatives – Guest page table is in physical address space – Need to walk PhysMap multiple times ? Need physical to machine mapping to walk guest page table ? Need physical to machine mapping for original virtual address ? Other Memory Virtualization Hardware Assists – Monitor Mode has its own address space ? No need to hide the monitor VM1 Interposition with Memory Virtualization Page Sharing Virtual Physical Machine ReadOnly Copyonwrte VM2 Virtual Physical
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