Re: [Qemu-devel] [PATCH v5] Xen PV Device

[Anthony Liguori <anthony@codemonkey.ws>]

Stefano Stabellini <stefano.stabellini@eu.citrix.com> writes:

> On Thu, 4 Jul 2013, Paul Durrant wrote:
>> Introduces a new Xen PV PCI device which will act as a binding point for
>> PV drivers for Xen.
>> The device has parameterized vendor-id, device-id and revision to allow to
>> be configured as a binding point for any vendor's PV drivers.
>> 
>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>> Cc: Stefano Stabellini <stefano.stabellini@citrix.com>
>> Reviewed-by: Andreas Färber <afaerber@suse.de>
>
> Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

(Just a nit and responding because this happens commonly).

You probably mean Reviewed-by.  Acked-by really means, "I am not the
maintainer of this area, I have not reviewed this patch, but I am
generally okay with the idea as best I can tell."

It's a very low vote of confidence.  I wouldn't apply a patch that only
had Acked-bys.

OTOH, Reviewed-by means, "I have reviewed the patch and believe it works
as described and meets project guidelines".  Based on your review of V4,
pretty sure that's what you mean here.

https://github.com/torvalds/linux/blob/master/Documentation/SubmittingPatches#L392

The distinction matters in practice because I have scripts to track
patches based on whether they've received Reviewed-bys or not.  I'm
often running into cases where people are Acked-by'ing instead of
Reviewed-by'ing patches and then wondering why they haven't gotten
merged...

Since this patch would come through your tree anyway, it doesn't matter
in practice for this patch.  I'll get off my soapbox now :-)

Regards,

Anthony Liguori

>
>
>> 
>> V5:
>> - Addresses comments from Andreas Färber
>> 
>> V4:
>> - Renamed from 'Citrix PV Bus' to 'Xen PV Device'
>> - Paramaterized vendor-id and device-id as requested by Stefano Stabellini
>> 
>> V3:
>> - Addresses comments from Anthony Liguori and Peter Maydell
>> 
>> V2:
>> - Addresses comments from Andreas Farber and Paolo Bonzini
>> 
>>  hw/xen/Makefile.objs     |    1 +
>>  hw/xen/xen_pvdevice.c    |  131 ++++++++++++++++++++++++++++++++++++++++++++++
>>  include/hw/pci/pci_ids.h |    5 +-
>>  trace-events             |    4 ++
>>  4 files changed, 139 insertions(+), 2 deletions(-)
>>  create mode 100644 hw/xen/xen_pvdevice.c
>> 
>> diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
>> index 2017560..cd2df6a 100644
>> --- a/hw/xen/Makefile.objs
>> +++ b/hw/xen/Makefile.objs
>> @@ -1,5 +1,6 @@
>>  # xen backend driver support
>>  common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
>> +common-obj-y += xen_pvdevice.o
>>  
>>  obj-$(CONFIG_XEN_I386) += xen_platform.o xen_apic.o
>>  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
>> diff --git a/hw/xen/xen_pvdevice.c b/hw/xen/xen_pvdevice.c
>> new file mode 100644
>> index 0000000..93dfab2
>> --- /dev/null
>> +++ b/hw/xen/xen_pvdevice.c
>> @@ -0,0 +1,131 @@
>> +/* Copyright (c) Citrix Systems Inc.
>> + * All rights reserved.
>> + * 
>> + * Redistribution and use in source and binary forms, 
>> + * with or without modification, are permitted provided 
>> + * that the following conditions are met:
>> + * 
>> + * *   Redistributions of source code must retain the above 
>> + *     copyright notice, this list of conditions and the 
>> + *     following disclaimer.
>> + * *   Redistributions in binary form must reproduce the above 
>> + *     copyright notice, this list of conditions and the 
>> + *     following disclaimer in the documentation and/or other 
>> + *     materials provided with the distribution.
>> + * 
>> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
>> + * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, 
>> + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
>> + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
>> + * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
>> + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
>> + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
>> + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
>> + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
>> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
>> + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
>> + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
>> + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
>> + * SUCH DAMAGE.
>> + */
>> +
>> +#include "hw/hw.h"
>> +#include "hw/pci/pci.h"
>> +#include "trace.h"
>> +
>> +#define TYPE_XEN_PV_DEVICE  "xen-pvdevice"
>> +
>> +#define XEN_PV_DEVICE(obj) \
>> +     OBJECT_CHECK(XenPVDevice, (obj), TYPE_XEN_PV_DEVICE)
>> +
>> +typedef struct XenPVDevice {
>> +    /*< private >*/
>> +    PCIDevice       parent_obj;
>> +    /*< public >*/
>> +    uint16_t        vendor_id;
>> +    uint16_t        device_id;
>> +    uint8_t         revision;
>> +    uint32_t        size;
>> +    MemoryRegion    mmio;
>> +} XenPVDevice;
>> +
>> +static uint64_t xen_pv_mmio_read(void *opaque, hwaddr addr,
>> +                                 unsigned size)
>> +{
>> +    trace_xen_pv_mmio_read(addr);
>> +
>> +    return ~(uint64_t)0;
>> +}
>> +
>> +static void xen_pv_mmio_write(void *opaque, hwaddr addr,
>> +                              uint64_t val, unsigned size)
>> +{
>> +    trace_xen_pv_mmio_write(addr);
>> +}
>> +
>> +static const MemoryRegionOps xen_pv_mmio_ops = {
>> +    .read = &xen_pv_mmio_read,
>> +    .write = &xen_pv_mmio_write,
>> +    .endianness = DEVICE_LITTLE_ENDIAN,
>> +};
>> +
>> +static int xen_pv_init(PCIDevice *pci_dev)
>> +{
>> +    XenPVDevice *d = XEN_PV_DEVICE(pci_dev);
>> +    uint8_t *pci_conf;
>> +
>> +    pci_conf = pci_dev->config;
>> +
>> +    pci_set_word(pci_conf + PCI_VENDOR_ID, d->vendor_id);
>> +    pci_set_word(pci_conf + PCI_SUBSYSTEM_VENDOR_ID, d->vendor_id);
>> +    pci_set_word(pci_conf + PCI_DEVICE_ID, d->device_id);
>> +    pci_set_word(pci_conf + PCI_SUBSYSTEM_ID, d->device_id);
>> +    pci_set_byte(pci_conf + PCI_REVISION_ID, d->revision);
>> +
>> +    pci_set_word(pci_conf + PCI_COMMAND, PCI_COMMAND_MEMORY);
>> +
>> +    pci_config_set_prog_interface(pci_conf, 0);
>> +
>> +    pci_conf[PCI_INTERRUPT_PIN] = 1;
>> +
>> +    memory_region_init_io(&d->mmio, &xen_pv_mmio_ops, d,
>> +                          "mmio", d->size);
>> +
>> +    pci_register_bar(pci_dev, 1, PCI_BASE_ADDRESS_MEM_PREFETCH,
>> +                     &d->mmio);
>> +
>> +    return 0;
>> +}
>> +
>> +static Property xen_pv_props[] = {
>> +    DEFINE_PROP_UINT16("vendor-id", XenPVDevice, vendor_id, PCI_VENDOR_ID_XEN),
>> +    DEFINE_PROP_UINT16("device-id", XenPVDevice, device_id, PCI_DEVICE_ID_XEN_PVDEVICE),
>> +    DEFINE_PROP_UINT8("revision", XenPVDevice, revision, 0x01),
>> +    DEFINE_PROP_UINT32("size", XenPVDevice, size, 0x400000),
>> +    DEFINE_PROP_END_OF_LIST()
>> +};
>> +
>> +static void xen_pv_class_init(ObjectClass *klass, void *data)
>> +{
>> +    DeviceClass *dc = DEVICE_CLASS(klass);
>> +    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>> +
>> +    k->init = xen_pv_init;
>> +    k->class_id = PCI_CLASS_SYSTEM_OTHER;
>> +    dc->desc = "Xen PV Device";
>> +    dc->props = xen_pv_props;
>> +}
>> +
>> +static const TypeInfo xen_pv_type_info = {
>> +    .name          = TYPE_XEN_PV_DEVICE,
>> +    .parent        = TYPE_PCI_DEVICE,
>> +    .instance_size = sizeof(XenPVDevice),
>> +    .class_init    = xen_pv_class_init,
>> +};
>> +
>> +static void xen_pv_register_types(void)
>> +{
>> +    type_register_static(&xen_pv_type_info);
>> +}
>> +
>> +type_init(xen_pv_register_types)
>> diff --git a/include/hw/pci/pci_ids.h b/include/hw/pci/pci_ids.h
>> index d8dc2f1..263bca3 100644
>> --- a/include/hw/pci/pci_ids.h
>> +++ b/include/hw/pci/pci_ids.h
>> @@ -142,8 +142,9 @@
>>  
>>  #define PCI_DEVICE_ID_INTEL_Q35_MCH      0x29c0
>>  
>> -#define PCI_VENDOR_ID_XEN               0x5853
>> -#define PCI_DEVICE_ID_XEN_PLATFORM      0x0001
>> +#define PCI_VENDOR_ID_XEN                0x5853
>> +#define PCI_DEVICE_ID_XEN_PLATFORM       0x0001
>> +#define PCI_DEVICE_ID_XEN_PVDEVICE       0x0002
>>  
>>  #define PCI_VENDOR_ID_NEC                0x1033
>>  #define PCI_DEVICE_ID_NEC_UPD720200      0x0194
>> diff --git a/trace-events b/trace-events
>> index c5f1ccb..0445853 100644
>> --- a/trace-events
>> +++ b/trace-events
>> @@ -1161,3 +1161,7 @@ kvm_run_exit(int cpu_index, uint32_t reason) "cpu_index %d, reason %d"
>>  # qom/object.c
>>  object_dynamic_cast_assert(const char *type, const char *target, const char *file, int line, const char *func) "%s->%s (%s:%d:%s)"
>>  object_class_dynamic_cast_assert(const char *type, const char *target, const char *file, int line, const char *func) "%s->%s (%s:%d:%s)"
>> +
>> +# hw/xen/xen_pvdevice.c
>> +xen_pv_mmio_read(uint64_t addr) "WARNING: read from Xen PV Device MMIO space (address %"PRIx64")"
>> +xen_pv_mmio_write(uint64_t addr) "WARNING: write to Xen PV Device MMIO space (address %"PRIx64")"
>> -- 
>> 1.7.10.4
>>