Re: [PATCH] PCI: hv: fix "spurious APIC interrupt" due to new vector reservation mode

[Thomas Gleixner]

On Sat, 14 Oct 2017, Dexuan Cui wrote:
> Last month the vector management code was reworked, and as a result of the
> changes, e.g. commit 22d0b12f3560 ("genirq/irqdomain: Add force
> reactivation flag to irq domains"), commit 4900be83602b ("x86/vector/msi:
> Switch to global reservation mode") etc, now we must add this new flag
> MSI_FLAG_MUST_REACTIVATE when calling pci_msi_create_irq_domain() on x86,
> otherwise Hyper-V PCIe pass-through can't work, and we get:
> "spurious APIC interrupt through vector ff on CPU#0, should never happen",
> this is because no valid MSI/MSI-X vector is allocated.
> 
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> ---
> 
> Currently the "reservation mode" patchset has not been in Linus's tree yet, so
> today's mainline hasn't shown the issue, but today's linux-next has shown the
> issue (PCIe pass-through on Hyper-V can't work).
> 
> I think any caller of pci_msi_create_irq_domain() that runs on x86 needs to
> be updated, but besides pci-hyper I'm not sure which callers run on x86.

I'm sure I thought about adding something to pci_msi_create_irq_domain() in
the first place, but then forgot about it again. I'll have a look tomorrow
morning.

Thanks,

	tglx