Re: [RFC PATCH 23/32] KVM: PPC: Book3S HV: Framework to handle HV Emulation Assist Interrupt

[Paul Mackerras <paulus@ozlabs.org>]

On Thu, Sep 27, 2018 at 11:08:26AM +1000, David Gibson wrote:
> On Fri, Sep 21, 2018 at 08:01:54PM +1000, Paul Mackerras wrote:
> > From: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> > 
> > A HEAI (hypervisor emulation assistance interrupt) occurs when a
> > hypervisor resource or instruction is used in a privileged but
> > non-hypervisor state and the LPCR_EVIRT bit is set in LPCR.  When
> > this occurs bit 45 is set in HSRR1.  Detect the occurrence of this,
> > and if userspace has enabled the nested virtualization capability
> > on the VM, then call the code to handle it accordingly.
> > 
> > With LPCR[EVIRT] set, we also get HEAI (without bit 45 set) for
> > mfspr or mtspr to unimplemented SPR numbers.  For these accesses,
> > we emulate the EVIRT=0 behaviour, which is to make the access
> > a no-op for privileged software unless it is accessing SPR 0,
> > 4, 5 or 6.  Problem-state accesses and accesses to SPR 0, 4, 5
> > or 6 generate an illegal-instruction type program interrupt.
> > 
> > Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> > Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> 
> Question, though: with the new mostly-paravirt approach to nested
> virt, what HV instructions do you still need to emulate?

Currently just tlbie.  If we add a H_TLBIE then not even that.

Paul.