“PV driver study”的版本间的差异
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The Xen paravirtualised MMU model instead requires that the guest be aware of the P2M mapping and be modified such that instead of writing page table entries mapping virtual addresses to the (pseudo-)physical address space it would instead write entries mapping virtual addresses directly to the machine address space by mapping performing the mapping from pseudo physical to machine addresses itself using the P2M as it writes its page tables. | The Xen paravirtualised MMU model instead requires that the guest be aware of the P2M mapping and be modified such that instead of writing page table entries mapping virtual addresses to the (pseudo-)physical address space it would instead write entries mapping virtual addresses directly to the machine address space by mapping performing the mapping from pseudo physical to machine addresses itself using the P2M as it writes its page tables. | ||
Page Type: | Page Type: | ||
| + | LN Page table page | ||
| + | Pages used as a page table at level N. There are separate types for each of the 4 levels on 64-bit and 3 levels on 32-bit PAE guests. | ||
| + | Segment descriptor page | ||
| + | Pages used as part of the Global or Local Descriptor tables (GDT/LDT). | ||
| + | Writeable | ||
| + | Page is writable. | ||
2019年12月3日 (二) 15:59的版本
Reference:
https://wiki.xen.org/wiki/Paravirtualization_(PV)
https://wiki.xen.org/wiki/Xen_VGA_Passthrough
https://wiki.xen.org/wiki/Xen_PCI_Passthrough
PV support is provided by the paravirt operations extensions (PVOPS) and PV front and back-end drivers that are shipped with Linux.
Xen Project Guest (DomU) support for Linux was introduced into the Linux kernel with version 2.6.24
Xen Project Control Domain (Dom0) support was added from version 2.6.37. The key drivers have been added to Linux v 3.0 and since additional drivers and optimizations are added.
backend driver = driver required in the Xen dom0 kernel
frontend driver = driver required in the Xen domU guest kernel
pciback and pcifront = drivers required for PCI passthrough. These drivers are not related to using PCI devices in dom0!
usbback and usbfront = drivers required for USB passthrough. These drivers are not related to using physical usb devices in dom0!
scsiback and scsifront = drivers required for PVSCSI passthrough. These drivers are not related to using SCSI devices in dom0!
- Xen VGA graphics adapter passthrough
requires IOMMU (Intel VT-d) support from the motherboard chipset, from the motherboard BIOS and from Xen.
VGA 需要bios, 但DomU没有bios, 所以这个需要bios 有虚拟化支持 .
Note that some graphics cards might work in the PV domU just by using the normal Xen PCI passthru.
新的图形卡应该直接看PCI passthru.
- PCI 穿越
Dom0 发现pci device 把它连接给 pciback driver. DomU 由 QEMU 模拟的 PCI bus 上找到 device 把它跟 pcifront river连接.
安全问题: VM buggy驱动可能损害别的系统. 可由VM 攻击其他系统 .
解法:IOMMU - (1)允许Xen限制device 可access 的memory. (2) allows Xen to give the device the same virtualized memory layout that the guest sees.
Dom 0 Load 方法:
(1) Static assignment for built-in xen-pciback: dom0 kernel command line: xen-pciback.hide=(08:00.0)(08.00.1)(device to passthru)
(2) dynamic load: Dom0 console:
modprobe xen-pciback xl pci-assignable-add <domain>:<bus>:<slot>.<function>
Guest configuration: guest kernel command-line
iommu=soft #pvops kernel swiotlb=force #classic Xen kernel
vm create configue file
pci=['80:00.0',<domain>:<bus>:<slot>.<function>,...]
on Dom0 console command line
xl pci-attach <domain-id> <pci device> <guest virtual slot number> xl pci-detach <domain-id> <pci device> <guest virtual slot number>
- Paravirtualised Memory Management
Reference: https://wiki.xen.org/wiki/X86_Paravirtualised_Memory_Management
Direct Paging: VM 直接写 machine address mapping
The Xen paravirtualised MMU model instead requires that the guest be aware of the P2M mapping and be modified such that instead of writing page table entries mapping virtual addresses to the (pseudo-)physical address space it would instead write entries mapping virtual addresses directly to the machine address space by mapping performing the mapping from pseudo physical to machine addresses itself using the P2M as it writes its page tables.
Page Type:
LN Page table page Pages used as a page table at level N. There are separate types for each of the 4 levels on 64-bit and 3 levels on 32-bit PAE guests. Segment descriptor page Pages used as part of the Global or Local Descriptor tables (GDT/LDT). Writeable Page is writable.
