On Tue, Dec 05, 2023 at 06:40:42PM +0000, Catalin Marinas wrote: > On Tue, Dec 05, 2023 at 05:50:27PM +0000, Marc Zyngier wrote: > > On Tue, 05 Dec 2023 17:33:01 +0000, > > Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > > Ideally we should do this for vfio only but we don't have an easy > > > way to convey this to KVM. > > > > But if we want to limit this to PCIe, we'll have to find out. The > > initial proposal (a long while ago) had a flag conveying some > > information, and I'd definitely feel more confident having something > > like that. > > We can add a VM_PCI_IO in the high vma flags to be set by > vfio_pci_core_mmap(), though it limits it to 64-bit architectures. KVM > knows this is PCI and relaxes things a bit. It's not generic though if > we need this later for something else. > > A question for Lorenzo: do these BARs appear in iomem_resource? We could > search that up instead of a flag, something like the page_is_ram() > helper. They do but an iomem_resource look-up alone if I am not mistaken would not tell us if it is PCI address space, we would need additional checks (like detecting if we are decoding an address within a PCI host bridge windows) to determine that if we go down this route. Lorenzo
