On Wed, Feb 05, 2025 at 09:17:31AM -0600, Bjorn Helgaas wrote: > Please run git log --oneline and match the subject line capitalization > style, i.e., > > PCI/MSI: Remove ... > > But it doesn't look like this actually *removes* the functionality, it > just implements it differently so it can be applied more selectively. > > So maybe the subject should say something like "control use of MSI > masking per IRQ domain, not globally" What about: PCI/MSI: convert pci_msi_ignore_mask to per MSI domain flag Which is slightly shorter? > > On Tue, Jan 14, 2025 at 11:33:13AM +0100, Roger Pau Monne wrote: > > Setting pci_msi_ignore_mask inhibits the toggling of the mask bit for both > > MSI and MSI-X entries globally, regardless of the IRQ chip they are using. > > Only Xen sets the pci_msi_ignore_mask when routing physical interrupts over > > event channels, to prevent PCI code from attempting to toggle the maskbit, > > as it's Xen that controls the bit. > > > > However, the pci_msi_ignore_mask being global will affect devices that use > > MSI interrupts but are not routing those interrupts over event channels > > (not using the Xen pIRQ chip). One example is devices behind a VMD PCI > > bridge. In that scenario the VMD bridge configures MSI(-X) using the > > normal IRQ chip (the pIRQ one in the Xen case), and devices behind the > > bridge configure the MSI entries using indexes into the VMD bridge MSI > > table. The VMD bridge then demultiplexes such interrupts and delivers to > > the destination device(s). Having pci_msi_ignore_mask set in that scenario > > prevents (un)masking of MSI entries for devices behind the VMD bridge. > > > > Move the signaling of no entry masking into the MSI domain flags, as that > > allows setting it on a per-domain basis. Set it for the Xen MSI domain > > that uses the pIRQ chip, while leaving it unset for the rest of the > > cases. > > > > Remove pci_msi_ignore_mask at once, since it was only used by Xen code, and > > with Xen dropping usage the variable is unneeded. > > > > This fixes using devices behind a VMD bridge on Xen PV hardware domains. > > > > Albeit Devices behind a VMD bridge are not known to Xen, that doesn't mean > > Linux cannot use them. By inhibiting the usage of > > VMD_FEAT_CAN_BYPASS_MSI_REMAP and the removal of the pci_msi_ignore_mask > > bodge devices behind a VMD bridge do work fine when use from a Linux Xen > > hardware domain. That's the whole point of the series. > > > > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> > > Needs an ack from Thomas. Thanks, moved him to the 'To:' field. Regards, Roger.
