[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH v3 1/2] nvmx: implement support for MSR bitmaps



> From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Sent: Tuesday, February 4, 2020 1:37 AM
> 
> Current implementation of nested VMX has a half baked handling of MSR
> bitmaps for the L1 VMM: it maps the L1 VMM provided MSR bitmap, but
> doesn't actually load it into the nested vmcs, and thus the nested
> guest vmcs ends up using the same MSR bitmap as the L1 VMM.
> 
> This is wrong as there's no assurance that the set of features enabled
> for the L1 vmcs are the same that L1 itself is going to use in the
> nested vmcs, and thus can lead to misconfigurations.
> 
> For example L1 vmcs can use x2APIC virtualization and virtual
> interrupt delivery, and thus some x2APIC MSRs won't be trapped so that
> they can be handled directly by the hardware using virtualization
> extensions. On the other hand, the nested vmcs created by L1 VMM might
> not use any of such features, so using a MSR bitmap that doesn't trap
> accesses to the x2APIC MSRs will be leaking them to the underlying
> hardware.
> 
> Fix this by crafting a merged MSR bitmap between the one used by L1
> and the nested guest.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.