On Wed, Jul 13, 2022 at 06:12:51PM +0000, Carl Vanderlip wrote:
> From: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
>
> If the allocation of multiple MSI vectors for multi-MSI fails in the core
> PCI framework, the framework will retry the allocation as a single MSI
> vector, assuming that meets the min_vecs specified by the requesting
> driver.
>
> Hyper-V advertises that multi-MSI is supported, but reuses the VECTOR
> domain to implement that for x86. The VECTOR domain does not support
> multi-MSI, so the alloc will always fail and fallback to a single MSI
> allocation.
>
> In short, Hyper-V advertises a capability it does not implement.
>
> Hyper-V can support multi-MSI because it coordinates with the hypervisor
> to map the MSIs in the IOMMU's interrupt remapper, which is something the
> VECTOR domain does not have. Therefore the fix is simple - copy what the
> x86 IOMMU drivers (AMD/Intel-IR) do by removing
> X86_IRQ_ALLOC_CONTIGUOUS_VECTORS after calling the VECTOR domain's
> pci_msi_prepare().
>
> Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs")
> Signed-off-by: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
> Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/1649856981-14649-1-git-send-email-quic_jhugo@xxxxxxxxxxx
> Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
> Signed-off-by: Carl Vanderlip <quic_carlv@xxxxxxxxxxx>
> ---
> drivers/pci/controller/pci-hyperv.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
You forgot to list the git commit id of this and the other commits here,
or anywhere else. Please fix that up and resend the series.
thanks,
greg k-h
