On Wed, Jul 13, 2022 at 06:12:51PM +0000, Carl Vanderlip wrote:
From: Jeffrey Hugo quic_jhugo@quicinc.com
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@quicinc.com Reviewed-by: Dexuan Cui decui@microsoft.com Link: https://lore.kernel.org/r/1649856981-14649-1-git-send-email-quic_jhugo@quici... Signed-off-by: Wei Liu wei.liu@kernel.org Signed-off-by: Carl Vanderlip quic_carlv@quicinc.com
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