RE: [PATCH AUTOSEL 6.3 06/17] x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline

[Michael Kelley (LINUX)]

From: Sasha Levin <sashal@xxxxxxxxxx> Sent: Thursday, June 29, 2023 12:01 PM
> 
> From: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> 
> [ Upstream commit 9636be85cc5bdd8b7a7f6a53405cbcc52161c93c ]
> 
> These commits
> 
> a494aef23dfc ("PCI: hv: Replace retarget_msi_interrupt_params with
> hyperv_pcpu_input_arg")
> 2c6ba4216844 ("PCI: hv: Enable PCI pass-thru devices in Confidential VMs")
> 
> update the Hyper-V virtual PCI driver to use the hyperv_pcpu_input_arg
> because that memory will be correctly marked as decrypted or encrypted
> for all VM types (CoCo or normal). But problems ensue when CPUs in the
> VM go online or offline after virtual PCI devices have been configured.

The two mentioned commits first appeared in 6.4.  So the problem fixed
by this patch doesn't occur with 6.3 and earlier.  There's no need to backport
this patch to stable releases.

Michael