[Xen-devel] Re: [PATCH 3/3] xen: implement unplug protocol in xen_platform

[Alexander Graf <agraf@xxxxxxx>]

On 16.06.2011, at 18:05, <stefano.stabellini@xxxxxxxxxxxxx> 
<stefano.stabellini@xxxxxxxxxxxxx> wrote:

> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> The unplug protocol is necessary to support PV drivers in the guest: the
> drivers expect to be able to "unplug" emulated disks and nics before
> initializing the Xen PV interfaces.
> It is responsibility of the guest to make sure that the unplug is done
> before the emulated devices or the PV interface start to be used.
> 
> We use pci_for_each_device to walk the PCI bus, identify the devices and
> disks that we want to disable and dynamically unplug them.

Kevin, please check the block parts of this code.
Michael, please check the PCI parts of this code.

Thanks :)

Alex

> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
> hw/xen_platform.c |   63 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 62 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/xen_platform.c b/hw/xen_platform.c
> index b167eee..9f8c843 100644
> --- a/hw/xen_platform.c
> +++ b/hw/xen_platform.c
> @@ -34,6 +34,9 @@
> #include "xen_backend.h"
> #include "rwhandler.h"
> #include "trace.h"
> +#include "hw/ide/internal.h"
> +#include "hw/ide/pci.h"
> +#include "hw/pci_ids.h"
> 
> #include <xenguest.h>
> 
> @@ -76,6 +79,54 @@ static void log_writeb(PCIXenPlatformState *s, char val)
> }
> 
> /* Xen Platform, Fixed IOPort */
> +#define UNPLUG_ALL_IDE_DISKS 1
> +#define UNPLUG_ALL_NICS 2
> +#define UNPLUG_AUX_IDE_DISKS 4
> +
> +static int unplug_param;
> +
> +static void unplug_nic(PCIBus *b, PCIDevice *d)
> +{
> +    if (d->config[0xa] == 0 && d->config[0xb] == 2) {
> +        pci_unplug_device(&(d->qdev));
> +    }
> +}
> +
> +static void pci_unplug_nics(PCIBus *bus)
> +{
> +    pci_for_each_device(bus, 0, unplug_nic);
> +}
> +
> +static void unplug_disks(PCIBus *b, PCIDevice *d)
> +{
> +    if (d->config[0xa] == 1 && d->config[0xb] == 1) {
> +        PCIIDEState *pci_ide = DO_UPCAST(PCIIDEState, dev, d);
> +        DriveInfo *di;
> +        int i = 0;
> +
> +        if (unplug_param & UNPLUG_AUX_IDE_DISKS)
> +            i++;
> +
> +        for (; i < 3; i++) {
> +            di = drive_get_by_index(IF_IDE, i); 
> +            if (di != NULL && di->bdrv != NULL && di->bdrv->type != 
> BDRV_TYPE_CDROM) {
> +                DeviceState *ds = bdrv_get_attached(di->bdrv);
> +                if (ds)
> +                    bdrv_detach(di->bdrv, ds);
> +                bdrv_close(di->bdrv);
> +                pci_ide->bus[di->bus].ifs[di->unit].bs = NULL;
> +                drive_put_ref(di);
> +            }
> +        }
> +        ide_bus_reset(&pci_ide->bus[0]);
> +        ide_bus_reset(&pci_ide->bus[1]);
> +    }
> +}
> +
> +static void pci_unplug_disks(PCIBus *bus)
> +{
> +    pci_for_each_device(bus, 0, unplug_disks);
> +}
> 
> static void platform_fixed_ioport_writew(void *opaque, uint32_t addr, 
> uint32_t val)
> {
> @@ -83,10 +134,20 @@ static void platform_fixed_ioport_writew(void *opaque, 
> uint32_t addr, uint32_t v
> 
>     switch (addr - XEN_PLATFORM_IOPORT) {
>     case 0:
> -        /* TODO: */
> +        unplug_param = val;
>         /* Unplug devices.  Value is a bitmask of which devices to
>            unplug, with bit 0 the IDE devices, bit 1 the network
>            devices, and bit 2 the non-primary-master IDE devices. */
> +        if (val & UNPLUG_ALL_IDE_DISKS || val & UNPLUG_AUX_IDE_DISKS) {
> +            DPRINTF("unplug disks\n");
> +            qemu_aio_flush();
> +            bdrv_flush_all();
> +            pci_unplug_disks(s->pci_dev.bus);
> +        }
> +        if (val & UNPLUG_ALL_NICS) {
> +            DPRINTF("unplug nics\n");
> +            pci_unplug_nics(s->pci_dev.bus);
> +        }
>         break;
>     case 2:
>         switch (val) {
> -- 
> 1.7.2.3
> 


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