Re: [PATCH V2] Add a new PIIX option to control PCI hot unplugging of devices on non-root buses

[Michael S. Tsirkin]

On Wed, Apr 29, 2020 at 06:54:52AM +0000, Ani Sinha wrote:
> 
> 
> > On Apr 29, 2020, at 12:22 PM, Michael S. Tsirkin <address@hidden> wrote:
> > 
> > On Wed, Apr 29, 2020 at 06:11:20AM +0000, Ani Sinha wrote:
> >> 
> >> 
> >>> On Apr 29, 2020, at 10:58 AM, Michael S. Tsirkin <address@hidden> wrote:
> >>> 
> >>> o if there's a need to disable
> >>> just one of these, commit log needs to do a better job documenting the
> >>> usecase.
> >> 
> >> The use case is simple. With this feature admins will be able to do what 
> >> they were forced to do from Windows driver level but now at the bus level. 
> >> Hence, 
> >> (a) They need not have access to the guest VM to change or update windows 
> >> driver registry settings. They can enable the same setting from admin 
> >> management console without any access to VM.
> >> (b) It is more robust. No need to mess with driver settings. Incorrect 
> >> settings can brick guest OS. Also no guest specific knowhow required.
> >> (c) It is more scalable since a single cluster wide setting can be used 
> >> for all VM power ons and the management plane can take care of the rest 
> >> automatically. No need to access individual VMs to enforce this.
> >> (d) I am told that the driver level solution does not persist across a 
> >> reboot. 
> >> 
> >> Ani
> > 
> > Looks like disabling both plug and unplug would also address these needs.
> 
> No the driver level solution does not prevent hot plugging of devices but 
> blocks just hot unplugging. The solution I am proposing tries to do the same 
> but from the bus/hypervisor level.

Why does the driver level solution need to prevent just hot unplugging?


> 
> > -- 
> > MST
> >