On Thu, Mar 13, 2025 at 11:30:28AM -0400, Jason Andryuk wrote: > On 2025-02-27 05:23, Roger Pau Monné wrote: > > On Wed, Feb 26, 2025 at 04:11:25PM -0500, Jason Andryuk wrote: > > > > > > The ath11k device supports and tries to enable 32 MSIs. Linux in PVH > > > dom0 and HVM domU fails enabling 32 and falls back to just 1, so that is > > > all that has been tested. > > > > DYK why it fails to enable 32? > > In Linux msi_capability_init() > > /* Reject multi-MSI early on irq domain enabled architectures */ > if (nvec > 1 && !pci_msi_domain_supports(dev, > MSI_FLAG_MULTI_PCI_MSI, ALLOW_LEGACY)) > return 1; > > MSI_FLAG_MULTI_PCI_MSI is only set for AMD and Intel interrupt remapping, > and Xen PVH and HVM don't have either of those. They are using "VECTOR", so > this check fails.
Oh, interesting. So classic PV MSI domain supports MSI_FLAG_MULTI_PCI_MSI, even when no IOMMU is exposed there either. Thanks, so it's nothing specific to Xen, just how Linux works. Roger.
