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New: nVMX: accurately emulate VMXON region

Bug 54521 [email protected] 1 participant 5 messages Feb 26, 2013 – Mar 17, 2015 KVM

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https://bugzilla.kernel.org/show_bug.cgi?id=54521

Summary: nVMX: accurately emulate VMXON region
Product: Virtualization
Version: unspecified
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: enhancement
Priority: P1
Component: kvm
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: No

According to the VMX spec, the VMXON instruction takes a "VMXON region", a 4096 byte memory region which the VMX implementation (in this case, our emulation in nested VMX) may use for its needs.

We currently have no need to for this memory area, because when our implementation needs to store extra data, it stores it in the vmx_vcpu structure (in L0 memory). However, we may want to store data in guest memory in the future - e.g. for making it easier to do live migration (see bug 53851).

In any case, according to the VMX spec, the VMXON instruction is supposed to verify that the memory pointed by the VMXON operand is 4K aligned and has the right physical address width, and its content has the right VMCS revision field (copied from VMX_BASIC). We don't do this currently.

Moreover, according to the spec, VMXON needs to save this pointer, and on VMPTRLD/VMCLEAR we need to verify that the given VMCS pointer is not the VMXON region.

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#1 lore raw

[Bug 54521] nVMX: accurately emulate VMXON region

https://bugzilla.kernel.org/show_bug.cgi?id=54521

Nadav Har'El <[email protected]> changed:

What |Removed |Added
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             Blocks|                            |53601
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#2 lore raw

[Bug 54521] nVMX: accurately emulate VMXON region

In reply to [email protected]

https://bugzilla.kernel.org/show_bug.cgi?id=54521

Bandan Das <[email protected]> changed:

What |Removed |Added
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CC| |[email protected]

--- Comment #1 from Bandan Das <[email protected]> --- Patches posted -
https://lkml.org/lkml/2014/5/6/29

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#3 lore raw

[Bug 54521] nVMX: accurately emulate VMXON region

In reply to [email protected]

https://bugzilla.kernel.org/show_bug.cgi?id=54521

Paolo Bonzini <[email protected]> changed:

What |Removed |Added
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             Status|NEW                         |RESOLVED
                 CC|                            |[email protected]
     Kernel Version|                            |3.16
         Resolution|---                         |CODE_FIX
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