On 14/03/2019 17:41, Anthony PERARD wrote: > Hi, > > On Wed, Mar 06, 2019 at 12:40:54PM +0000, Igor Druzhinin wrote: >> This aperture doesn't exist in OVMF and trying to use it causes > > I'm trying to understand what you mean by writing "doesn't exist in > OVMF". Are prefetchable BAR not handled by ScanForRootBridges() ? > Or is it the emulation of the config space that isn't correct? > Maybe QEMU should lies about a BAR been prefetchable?
The problem here is: hvmloader places BARs initially disregarding prefetchable bit in an arbitrary order because essentially there is only 1 aperture for the host bridge in emulated system under Xen (and KVM as well). In PcatPciRootBridgeParseBars() we construct apertures for high level OVMF code by reading the BAR placement information after hvmloader. It often appears that there are prefetchable and non-prefetchable BARs coexist with each other and make prefetchable and non-prefetchable apertures overlap. This eventually triggers an assertion in high level OVMF code because that shouldn't happen. OVMF for KVM is not using prefetchable BAR at all - see PciHostBridgeGetRootBridges() in which it passes mNonExistAperture dummy object to high level code. I think it's wrong to construct a prefetchable aperture for Xen and this code should be removed as it's done for QEMU-KVM. Do you think this patch needs to do that? Igor _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
