Re: [kvm-devel] PCI IO regions must be power of two
From: Marcelo Tosatti Index: kvm-userspace.hotplug2/qemu/hw/pci.c === --- kvm-userspace.hotplug2.orig/qemu/hw/pci.c +++ kvm-userspace.hotplug2/qemu/hw/pci.c @@ -236,6 +236,13 @@ void pci_register_io_region(PCIDevice *p if ((unsigned int)region_num = PCI_NUM_REGIONS) return; + +/* IO region size must be power of two */ +if (type == PCI_ADDRESS_SPACE_IO (size (size-1))) { Why only for PCI IO regions ? Don't PCI memory regions have the same restriction ? +size = size 1; +size = size-1; That would not make size a power of 2 (e.g. size=7 -- size=12). +} + Regards, Uri. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] PCI IO regions must be power of two
On Wed, Mar 12, 2008 at 08:39:11AM -0700, Uri Lublin wrote: From: Marcelo Tosatti Index: kvm-userspace.hotplug2/qemu/hw/pci.c === --- kvm-userspace.hotplug2.orig/qemu/hw/pci.c +++ kvm-userspace.hotplug2/qemu/hw/pci.c @@ -236,6 +236,13 @@ void pci_register_io_region(PCIDevice *p if ((unsigned int)region_num = PCI_NUM_REGIONS) return; + +/* IO region size must be power of two */ +if (type == PCI_ADDRESS_SPACE_IO (size (size-1))) { Why only for PCI IO regions ? Don't PCI memory regions have the same restriction ? Yes, they do. +size = size 1; +size = size-1; That would not make size a power of 2 (e.g. size=7 -- size=12). Right, sorry. I'll resend a patch to have virtio allocate IO regions with proper sizes and warn if the IO _or_ memory region are not power of two, as Anthony suggested. Since this problem is only visible with device hotplug (QEMU will allocate the region offsets properly during initialization) I'll wait for that to hit the tree. Thanks. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
[kvm-devel] PCI IO regions must be power of two
Anthony, Both virtio-net and virtio-block currently register PCI IO space regions that are not power of two in size. The decoding process to discover the size of a PCI resource expects it to be a power of two. The PCI controller masks the size out of what is written into config_space + 0x10 + (4 * region_num) The result is that the size is calculated and registered erroneously by the OS: [EMAIL PROTECTED] ~]# cat /proc/ioports | grep virtio c200-c203 : virtio-pci This is a virtio-block device whose BAR0 has length (16+20)-1, not 4. BAR0: I/O at 0xc200 [0xc223]. I suggest forcing the size to be power of two as follows: Index: kvm-userspace.hotplug2/qemu/hw/pci.c === --- kvm-userspace.hotplug2.orig/qemu/hw/pci.c +++ kvm-userspace.hotplug2/qemu/hw/pci.c @@ -236,6 +236,13 @@ void pci_register_io_region(PCIDevice *p if ((unsigned int)region_num = PCI_NUM_REGIONS) return; + +/* IO region size must be power of two */ +if (type == PCI_ADDRESS_SPACE_IO (size (size-1))) { +size = size 1; +size = size-1; +} + r = pci_dev-io_regions[region_num]; r-addr = -1; r-size = size; - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
Re: [kvm-devel] PCI IO regions must be power of two
Marcelo Tosatti wrote: Anthony, Both virtio-net and virtio-block currently register PCI IO space regions that are not power of two in size. The decoding process to discover the size of a PCI resource expects it to be a power of two. The PCI controller masks the size out of what is written into config_space + 0x10 + (4 * region_num) The result is that the size is calculated and registered erroneously by the OS: [EMAIL PROTECTED] ~]# cat /proc/ioports | grep virtio c200-c203 : virtio-pci This is a virtio-block device whose BAR0 has length (16+20)-1, not 4. BAR0: I/O at 0xc200 [0xc223]. I suggest forcing the size to be power of two as follows: A quick grep of the source show that virtio seems to be the only device that isn't behaving here. I suggest modifying the virtio.c to always use a power of two and then perhaps adding a check in hw/pci.c to validate that the registered region is a power of two in size. Regards, Anthony Liguori Index: kvm-userspace.hotplug2/qemu/hw/pci.c === --- kvm-userspace.hotplug2.orig/qemu/hw/pci.c +++ kvm-userspace.hotplug2/qemu/hw/pci.c @@ -236,6 +236,13 @@ void pci_register_io_region(PCIDevice *p if ((unsigned int)region_num = PCI_NUM_REGIONS) return; + +/* IO region size must be power of two */ +if (type == PCI_ADDRESS_SPACE_IO (size (size-1))) { +size = size 1; +size = size-1; +} + r = pci_dev-io_regions[region_num]; r-addr = -1; r-size = size; - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel