On 6/7/2022 5:05 AM, Sasha Levin wrote:

On Mon, Jun 06, 2022 at 05:02:41PM +0000, Dexuan Cui wrote:

...

...

From: Sasha Levin sashal@kernel.org Sent: Monday, June 6, 2022 4:08 AM To: stable-commits@vger.kernel.org; quic_jhugo@quicinc.com Cc: KY Srinivasan kys@microsoft.com; Haiyang Zhang haiyangz@microsoft.com; Stephen Hemminger sthemmin@microsoft.com; Wei Liu wei.liu@kernel.org; Dexuan Cui decui@microsoft.com; Lorenzo Pieralisi lorenzo.pieralisi@arm.com; Rob Herring robh@kernel.org; Krzysztof Wilczyński kw@linux.com; Bjorn Helgaas bhelgaas@google.com Subject: Patch "PCI: hv: Fix multi-MSI to allow more than one MSI vector" has been added to the 5.18-stable tree

This is a note to let you know that I've just added the patch titled

PCI: hv: Fix multi-MSI to allow more than one MSI vector

(+ stable@vger.kernel.org)

Hi Sasha and stable kernel maintainers, If we want to support multi-MSI in the pci-hyperv driver, we need all of the 4 patches:

08e61e861a0e ("PCI: hv: Fix multi-MSI to allow more than one MSI vector") 455880dfe292 ("PCI: hv: Fix hv_arch_irq_unmask() for multi-MSI") b4b77778ecc5 ("PCI: hv: Reuse existing IRTE allocation in compose_msi_msg()") a2bad844a67b ("PCI: hv: Fix interrupt mapping for multi-MSI")

Multi-MSI can't work properly if we only pick up the first patch.

We need to either pick up all the 4 patches to 5.18/5.17/etc. or pick up nothing. I suggest we pick up all the 4 patches. The patch author Jeffrey may want to chime in.

Hey Dexuan,

I wasn't trying to enable multi-MSI, I was just picking something that looked like a fix. I'll go ahead and drop it, thanks!

IMO it is a fix to an existing feature - not adding a new one. The driver enables Multi-MSI, advertises the support, but it doesn't work. The changes fix the driver so it actually works.

It would be my preference for these to be backported. Ideally the distros would then pick them up, and it would make support easier.