Re: [Libguestfs] [PATCH] aarch64: Enable virtio-pci, replacing virtio-mmio.

This patch causes aarch64 to use virtio-pci instead of virtio-mmio. Virtio-pci is considerably faster than virtio-mmio, it's more like how other architectures work, and it supports hotplugging (although it's not likely we'd use the latter feature). I'm not necessarily suggesting that we apply this. Laine (CC'd) has some further patches to libvirt lined up which AIUI would make it simpler to do this.

Thanks: Laine Stump, Andrea Bolognani, Marcel Apfelbaum. --- src/guestfs-internal.h | 6 +++--- src/launch-libvirt.c | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+), 3 deletions(-) diff --git a/src/guestfs-internal.h b/src/guestfs-internal.h index d437b9a..428da7f 100644 --- a/src/guestfs-internal.h +++ b/src/guestfs-internal.h @@ -137,17 +137,17 @@ /* Differences in device names on ARM (virtio-mmio) vs normal * hardware with PCI. */ -#if !defined(__arm__) && !defined(__aarch64__) +#if !defined(__arm__) #define VIRTIO_BLK "virtio-blk-pci" #define VIRTIO_SCSI "virtio-scsi-pci" #define VIRTIO_SERIAL "virtio-serial-pci" #define VIRTIO_NET "virtio-net-pci" -#else /* ARM */ +#else /* ARMv7 */ #define VIRTIO_BLK "virtio-blk-device" #define VIRTIO_SCSI "virtio-scsi-device" #define VIRTIO_SERIAL "virtio-serial-device" #define VIRTIO_NET "virtio-net-device" -#endif /* ARM */ +#endif /* ARMv7 */ /* Machine types. */ #ifdef __arm__ diff --git a/src/launch-libvirt.c b/src/launch-libvirt.c index d8479dc..1ac5604 100644 --- a/src/launch-libvirt.c +++ b/src/launch-libvirt.c @@ -950,6 +950,13 @@ static int construct_libvirt_xml_disk_source_hosts (guestfs_h *g, xmlTextWriterP static int construct_libvirt_xml_disk_source_seclabel (guestfs_h *g, const struct backend_libvirt_data *data, xmlTextWriterPtr xo); static int construct_libvirt_xml_appliance (guestfs_h *g, const struct libvirt_xml_params *params, xmlTextWriterPtr xo); +static int construct_libvirt_xml_virtio_pci_address (guestfs_h *g, xmlTextWriterPtr xo, int slot); +/* Don't use slot 1, since can be used by video. */ +#define VIRTIO_PCI_SLOT_RNG 2 +#define VIRTIO_PCI_SLOT_SCSI 3 +#define VIRTIO_PCI_SLOT_SERIAL 4 +#define VIRTIO_PCI_SLOT_NETWORK 5 + /* These macros make it easier to write XML, but they also make a lot * of assumptions: * @@ -1337,6 +1344,9 @@ construct_libvirt_xml_devices (guestfs_h *g, attribute ("model", "random"); string ("/dev/urandom"); } end_element (); + if (construct_libvirt_xml_virtio_pci_address (g, xo, + VIRTIO_PCI_SLOT_RNG) == -1) + return -1; } end_element (); } @@ -1345,6 +1355,9 @@ construct_libvirt_xml_devices (guestfs_h *g, attribute ("type", "scsi"); attribute ("index", "0"); attribute ("model", "virtio-scsi"); + if (construct_libvirt_xml_virtio_pci_address (g, xo, + VIRTIO_PCI_SLOT_SCSI) == -1) + return -1; } end_element (); /* Disks. */ @@ -1382,6 +1395,9 @@ construct_libvirt_xml_devices (guestfs_h *g, attribute ("type", "virtio"); attribute ("name", "org.libguestfs.channel.0"); } end_element (); + if (construct_libvirt_xml_virtio_pci_address (g, xo, + VIRTIO_PCI_SLOT_SERIAL) == -1) + return -1; } end_element (); /* Connect to libvirt bridge (see: RHBZ#1148012). */ @@ -1394,6 +1410,9 @@ construct_libvirt_xml_devices (guestfs_h *g, start_element ("model") { attribute ("type", "virtio"); } end_element (); + if (construct_libvirt_xml_virtio_pci_address (g, xo, + VIRTIO_PCI_SLOT_NETWORK) == -1) + return -1; } end_element (); } @@ -1986,6 +2005,28 @@ find_secret (guestfs_h *g, return 0; } +/** + * On aarch64 only, to force libvirt to use virtio-pci instead of + * virtio-mmio, we assign every virtio device to a unique function

+ * within the (implicitly created) pcie-root bus. Every virtio device + * must have a unique slot number.

+ */ +static int +construct_libvirt_xml_virtio_pci_address (guestfs_h *g, + xmlTextWriterPtr xo, + int slot) +{ +#if defined(__aarch64__) + start_element ("address") { + attribute ("type", "pci"); + attribute ("bus", "0"); + attribute_format ("slot", "%d", slot); + } end_element (); +#endif + + return 0; +} + static int is_blk (const char *path) {