On Thu, Sep 14, 2023 at 12:14:06PM -0700, Shannon Nelson wrote: > The new MSI dynamic allocation machinery is great for making the irq > management more flexible. It includes caching information about the > MSI domain which gets reused on each new open of a VFIO fd. However, > this causes an issue when the underlying hardware has flexible MSI-x > configurations, as a changed configuration doesn't get seen between > new opens, and is only refreshed between PCI unbind/bind cycles. > > In our device we can change the per-VF MSI-x resource allocation > without the need for rebooting or function reset. For example, > > 1. Initial power up and kernel boot: > # lspci -s 2e:00.1 -vv | grep MSI-X > Capabilities: [a0] MSI-X: Enable+ Count=8 Masked- > > 2. Device VF configuration change happens with no reset Is this an out of tree driver problem? The intree way to alter the MSI configuration is via sriov_set_msix_vec_count, and there is only one in-tree driver that uses it right now. If something is going wrong here it should be fixed in the sriov_set_msix_vec_count() machinery, possibly in the pci core to synchronize the msi_domain view of the world. Jason
