Re: [kvm-unit-tests PATCH] x86/run: Use separate "-accel" option to configure the accelerator

[Sean Christopherson <seanjc@google.com>]

On Tue, Jun 02, 2026, Sean Christopherson wrote:
> On Tue, Jun 02, 2026, Xiaoyao Li wrote:
> > On 5/29/2026 8:09 AM, Xiaoyao Li wrote:
> > > On 5/28/2026 9:00 PM, Sean Christopherson wrote:
> > > > On Thu, May 28, 2026, Xiaoyao Li wrote:
> > > > > When configuring accelerator via machine's "accel" property, it cannot
> > > > > pass additional ACCEL_PROPS. For example, it hits following error when
> > > > > configuring KVM with "notify-vmexit":
> > > > > 
> > > > >    # ACCEL="kvm,notify-vmexit=internal-error" ./x86-run x86/apic.c
> > > > >    #   qemu-system-x86_64: Property
> > > > > 'pc-i440fx-11.1-machine.notify- vmexit' not found
> > > > > 
> > > > > Switch to use separate "-accel" option to configure the accelerator.
> > > > > 
> > > > > Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> > > > > ---
> > > > >   x86/run | 2 +-
> > > > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/x86/run b/x86/run
> > > > > index dd38f14c871f..a68d469dd1b8 100755
> > > > > --- a/x86/run
> > > > > +++ b/x86/run
> > > > > @@ -43,7 +43,7 @@ fi
> > > > >   pit="-global kvm-pit.lost_tick_policy=discard"
> > > > >   command="${qemu} --no-reboot -nodefaults $pit $pc_testdev
> > > > > -display none -serial stdio $pci_testdev"
> > > > > -command+=" -machine accel=$ACCEL$ACCEL_PROPS"
> > > > > +command+=" -accel $ACCEL$ACCEL_PROPS"
> > > > 
> > > > This breaks my setup for specifying kernel_irqchip=split.
> > > > 
> > > >    qemu: -accel kvm,kernel_irqchip=split: Property 'kvm-
> > > > accel.kernel_irqchip' not found
> > > 
> > > If you switch "kernel_irqchip" to "kernel-irqchip", it should work again.
> > > 
> > > This needs to be fixed on QEMU side. I'll look at it.
> > 
> > Well, I feel hard to justify a QEMU "fix" for it.
> > 
> > "kernel_irqchip" was a property of "machine" in old QEMU, and QEMU switched
> > it to "kernel-irqchip" automatically.
> > 
> > Then QEMU moved it to be a property of "accel", while keeping the
> > compatibility when users configure it via "machine" that QEMU internally
> > setting it to accel's property in this case.
> > 
> > However, "kernel_irqchip" is only valid on "machine", but not on "accel".
> > 
> > For this KVM unit test issue, do we need to add workaround to keep your
> > (work-by-accident) usage working? or just kill it?
> 
> Nah, just switch to "accel" and call it good.  I'm likely the one and only user
> of kernel_irqchip.

There's another problem: the CET and LAM tests force -enable-kvm:

  [cet]
  file = cet.flat
  arch = x86_64
  smp = 2
  qemu_params = -enable-kvm -m 2048 -cpu host

  [lam]
  file = lam.flat
  arch = x86_64
  qemu_params = -enable-kvm -cpu max

Which apparently is wired up to "-machine accel=" under the hood, because they
get skipped with:

  SKIP cet (qemu: The -accel and "-machine accel=" options are incompatible)
  SKIP lam (qemu: The -accel and "-machine accel=" options are incompatible)