On Tue, Apr 28, 2015 at 11:12:10AM +0800, Jason Wang wrote: > > > On Mon, Apr 27, 2015 at 7:02 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > >On Thu, Apr 23, 2015 at 02:21:48PM +0800, Jason Wang wrote: > >> This patch increases the maximum number of virtqueues for pci from 64 > >> to 513. This will allow booting a virtio-net-pci device with 256 queue > >> pairs on recent Linux host (which supports up to 256 tuntap queue > >>pairs). > >> To keep migration compatibility, 64 was kept for legacy machine > >> types. This is because qemu in fact allows guest to probe the limit of > >> virtqueues through trying to set queue_sel. So for legacy machine > >> type, we should make sure setting queue_sel to more than 63 won't > >> make effect. > > > >This isn't a documented interface, and no guest that I know of does > >this. Accordingly, I think we should drop everything except the > >hw/virtio/virtio-pci.c change. > > We leave a chance for guest to use such undocumented behavior, so > technically we'd better keep it and it maybe too late for us to fix if we > find such a guest in the future. And consider keeping this compatibility was > really not hard, so I suggest to include this.
Reminds me of https://xkcd.com/1172/ We don't do this kind of thing. > > > > > >> Cc: Paolo Bonzini <pbonz...@redhat.com> > >> Cc: Richard Henderson <r...@twiddle.net> > >> Cc: Michael S. Tsirkin <m...@redhat.com> > >> Cc: Alexander Graf <ag...@suse.de> > >> Cc: qemu-...@nongnu.org > >> Signed-off-by: Jason Wang <jasow...@redhat.com> > >> --- > >> hw/i386/pc_piix.c | 5 +++++ > >> hw/i386/pc_q35.c | 5 +++++ > >> hw/ppc/spapr.c | 5 +++++ > >> hw/virtio/virtio-pci.c | 6 +++++- > >> 4 files changed, 20 insertions(+), 1 deletion(-) > >> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c > >> index 212e263..6e098ce 100644 > >> --- a/hw/i386/pc_piix.c > >> +++ b/hw/i386/pc_piix.c > >> @@ -49,6 +49,7 @@ > >> #include "hw/acpi/acpi.h" > >> #include "cpu.h" > >> #include "qemu/error-report.h" > >> +#include "hw/virtio/virtio-bus.h" > >> #ifdef CONFIG_XEN > >> # include <xen/hvm/hvm_info_table.h> > >> #endif > >> @@ -312,6 +313,10 @@ static void pc_init_pci(MachineState *machine) > >> static void pc_compat_2_3(MachineState *machine) > >> { > >> + ObjectClass *klass = object_class_by_name("virtio-pci-bus"); > >> + VirtioBusClass *k = VIRTIO_BUS_CLASS(klass); > >> + > >> + k->queue_max = 64; > >> } > >> static void pc_compat_2_2(MachineState *machine) > >> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c > >> index e67f2de..ff7c414 100644 > >> --- a/hw/i386/pc_q35.c > >> +++ b/hw/i386/pc_q35.c > >> @@ -45,6 +45,7 @@ > >> #include "hw/usb.h" > >> #include "hw/cpu/icc_bus.h" > >> #include "qemu/error-report.h" > >> +#include "include/hw/virtio/virtio-bus.h" > >> /* ICH9 AHCI has 6 ports */ > >> #define MAX_SATA_PORTS 6 > >> @@ -291,6 +292,10 @@ static void pc_q35_init(MachineState *machine) > >> static void pc_compat_2_3(MachineState *machine) > >> { > >> + ObjectClass *klass = object_class_by_name("virtio-pci-bus"); > >> + VirtioBusClass *k = VIRTIO_BUS_CLASS(klass); > >> + > >> + k->queue_max = 64; > >> } > >> static void pc_compat_2_2(MachineState *machine) > >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > >> index 8e43aa2..ee8f6a3 100644 > >> --- a/hw/ppc/spapr.c > >> +++ b/hw/ppc/spapr.c > >> @@ -50,6 +50,7 @@ > >> #include "hw/pci/pci.h" > >> #include "hw/scsi/scsi.h" > >> #include "hw/virtio/virtio-scsi.h" > >> +#include "hw/virtio/virtio-bus.h" > >> #include "exec/address-spaces.h" > >> #include "hw/usb.h" > >> @@ -1827,6 +1828,10 @@ static const TypeInfo spapr_machine_info = { > >> static void spapr_compat_2_3(Object *obj) > >> { > >> + ObjectClass *klass = object_class_by_name("virtio-pci-bus"); > >> + VirtioBusClass *k = VIRTIO_BUS_CLASS(klass); > >> + > >> + k->queue_max = 64; > >> } > >> static void spapr_compat_2_2(Object *obj) > >> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > >> index 7d01500..c510cb7 100644 > >> --- a/hw/virtio/virtio-pci.c > >> +++ b/hw/virtio/virtio-pci.c > >> @@ -42,7 +42,11 @@ > >> * configuration space */ > >> #define VIRTIO_PCI_CONFIG_SIZE(dev) > >>VIRTIO_PCI_CONFIG_OFF(msix_enabled(dev)) > >> -#define VIRTIO_PCI_QUEUE_MAX 64 > >> +/* The number was chose to be greater than both the the number of max > >> + * vcpus supported by host and the number of max tuntap queues support > >> + * by host and also leave some spaces for future. > >> + */ > >> +#define VIRTIO_PCI_QUEUE_MAX 1024 > >> static void virtio_pci_bus_new(VirtioBusState *bus, size_t > >>bus_size, > >> VirtIOPCIProxy *dev); > >> -- 2.1.0
