** Also affects: linux (Ubuntu Disco)
   Importance: Undecided
       Status: New

** Also affects: linux (Ubuntu Eoan)
   Importance: Undecided
       Status: Incomplete

** Also affects: linux (Ubuntu Cosmic)
   Importance: Undecided
       Status: New

** Changed in: linux (Ubuntu Eoan)
       Status: Incomplete => In Progress

** Changed in: linux (Ubuntu Eoan)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: linux (Ubuntu Disco)
       Status: New => In Progress

** Changed in: linux (Ubuntu Disco)
     Assignee: (unassigned) => dann frazier (dannf)

You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.

  Address performance issue w/ GICv4-based guests

Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Cosmic:
Status in linux source package in Disco:
  In Progress
Status in linux source package in Eoan:
  In Progress

Bug description:
  Performance is degraded when a guest is booted w/ vgic v4 support enabled. 

  [Test Case]
  I used a HiSilicon D06 system w/ an Intel 82599 10Gbps NIC. I passed through 
a VF to a guest, and ran "netperf -H <host>" against a 10Gbps-capable target. 
With vgic v4 support, I'm only seeing 5-6Gbps. With vgic v3 support, this was 
in the 9Gbps spectrum. And, after applying the upstream fix, I'm also seeing 
>9Gbps w/ vgic v4 enabled.

  Note: to enable vgic v4 support, pass "kvm-arm.vgic_v4_enable=1" on
  the host kernel cmdline.

  ca71228b42a96 arm64: KVM: Always set ICH_HCR_EL2.EN if GICv4 is enabled

  [Regression Risk]
  The fix is restricted to the ARM/KVM subsystem.

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