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Re: [libvirt] [PATCH] Add persistence of PCI addresses to QEMU



On Thu, Feb 11, 2010 at 04:40:43PM +0000, Daniel P. Berrange wrote:
> Current PCI addresses are allocated at time of VM startup.
> To make them truely persistent, it is neccessary to do this
> at time of virDomainDefine/virDomainCreate. The code in
> qemuStartVMDaemon still remains in order to cope with upgrades
> from older libvirt releases
> 
> * src/qemu/qemu_driver.c: Rename existing qemuAssignPCIAddresses
>   to qemuDetectPCIAddresses. Add new qemuAssignPCIAddresses which
>   does auto-allocation upfront. Call qemuAssignPCIAddresses from
>   qemuDomainDefine and qemuDomainCreate to assign PCI addresses that
>   can then be persisted. Don't clear PCI addresses at shutdown if
>   they are intended to be persistent
> ---
>  src/qemu/qemu_driver.c |   84 +++++++++++++++++++++++++++++++++++++++++++++---
>  1 files changed, 79 insertions(+), 5 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 03d0f5f..69187fc 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -95,6 +95,7 @@ struct _qemuDomainObjPrivate {
>      int *vcpupids;
>  
>      qemuDomainPCIAddressSetPtr pciaddrs;
> +    int persistentAddrs;
>  };
>  
>  static int qemudShutdown(void);
> @@ -857,6 +858,7 @@ qemuReconnectDomain(void *payload, const char *name ATTRIBUTE_UNUSED, void *opaq
>      virDomainObjPtr obj = payload;
>      struct qemud_driver *driver = opaque;
>      qemuDomainObjPrivatePtr priv;
> +    unsigned long long qemuCmdFlags;
>  
>      virDomainObjLock(obj);
>  
> @@ -872,6 +874,15 @@ qemuReconnectDomain(void *payload, const char *name ATTRIBUTE_UNUSED, void *opaq
>          goto error;
>      }
>  
> +    /* XXX we should be persisting the original flags in the XML
> +     * not re-detecting them, since the binary may have changed
> +     * since launch time */

  But where would we store them ? It sounds a bit strange, it's emulator
properties, not really domain ones, and I think we sound only store in
the domain what specific flags might be needed from the emulator, not
the full set (and this could change over time as a domain is being
modified).

> +    if (qemudExtractVersionInfo(obj->def->emulator,
> +                                NULL,
> +                                &qemuCmdFlags) >= 0 &&
> +        (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE))
> +        priv->persistentAddrs = 1;
> +
>      if (!(priv->pciaddrs = qemuDomainPCIAddressSetCreate(obj->def)))
>          goto error;
>  
> @@ -1976,7 +1987,7 @@ qemuGetPCIWatchdogVendorProduct(virDomainWatchdogDefPtr def,
>   * some static addrs on CLI. Have to check that...
>   */
>  static int
> -qemuAssignPCIAddresses(virDomainObjPtr vm,
> +qemuDetectPCIAddresses(virDomainObjPtr vm,
>                         qemuMonitorPCIAddress *addrs,
>                         int naddrs)
>  {
> @@ -2098,7 +2109,7 @@ qemuInitPCIAddresses(struct qemud_driver *driver,
>                                             &addrs);
>      qemuDomainObjExitMonitorWithDriver(driver, vm);
>  
> -    ret = qemuAssignPCIAddresses(vm, addrs, naddrs);
> +    ret = qemuDetectPCIAddresses(vm, addrs, naddrs);
>  
>      VIR_FREE(addrs);
>  
> @@ -2141,6 +2152,44 @@ static int qemudNextFreeVNCPort(struct qemud_driver *driver ATTRIBUTE_UNUSED) {
>      return -1;
>  }
>  
> +
> +static int
> +qemuAssignPCIAddresses(virDomainDefPtr def)
> +{
> +    int ret = -1;
> +    unsigned long long qemuCmdFlags = 0;
> +    qemuDomainPCIAddressSetPtr addrs = NULL;
> +    struct stat sb;
> +
> +    if (stat(def->emulator, &sb) < 0) {
> +        virReportSystemError(errno,
> +                             _("Cannot find QEMU binary %s"),
> +                             def->emulator);
> +        goto cleanup;
> +    }

  do we really need to update that every time ? We can't cache forever
but it's not like the emulator is changing every second. Maybe we need
to put a watch on the emulator at the driver level and keep this in
the driver.

> +    if (qemudExtractVersionInfo(def->emulator,
> +                                NULL,
> +                                &qemuCmdFlags) < 0)
> +        goto cleanup;
> +
> +    if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
> +        if (!(addrs = qemuDomainPCIAddressSetCreate(def)))
> +            goto cleanup;
> +
> +        if (qemuAssignDevicePCISlots(def, addrs) < 0)
> +            goto cleanup;
> +    }
> +
> +    ret = 0;
> +
> +cleanup:
> +    qemuDomainPCIAddressSetFree(addrs);
> +
> +    return ret;
> +}
> +
> +
>  static pciDeviceList *
>  qemuGetPciHostDeviceList(virDomainDefPtr def)
>  {
> @@ -2662,7 +2711,15 @@ static int qemudStartVMDaemon(virConnectPtr conn,
>          goto cleanup;
>      }
>  
> +    /*
> +     * Normally PCI addresses are assigned inhe virDomainCreate
> +     * or virDomainDefine methods. We might still need to assign
> +     * some here to cope with the question of upgrades. Regardless
> +     * we also need to populate the PCi address set cache for later
> +     * use in hotplug
> +     */
>      if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
> +        /* Populate cache with current addresses */
>          if (priv->pciaddrs) {
>              qemuDomainPCIAddressSetFree(priv->pciaddrs);
>              priv->pciaddrs = NULL;
> @@ -2670,8 +2727,14 @@ static int qemudStartVMDaemon(virConnectPtr conn,
>          if (!(priv->pciaddrs = qemuDomainPCIAddressSetCreate(vm->def)))
>              goto cleanup;
>  
> +
> +        /* Assign any remaining addresses */
>          if (qemuAssignDevicePCISlots(vm->def, priv->pciaddrs) < 0)
>              goto cleanup;
> +
> +        priv->persistentAddrs = 1;
> +    } else {
> +        priv->persistentAddrs = 0;
>      }
>  
>      vm->def->id = driver->nextvmid++;
> @@ -2903,10 +2966,12 @@ static void qemudShutdownVMDaemon(struct qemud_driver *driver,
>          VIR_FREE(vm->def->seclabel.imagelabel);
>      }
>  
> -    virDomainDefClearPCIAddresses(vm->def);
>      virDomainDefClearDeviceAliases(vm->def);
> -    qemuDomainPCIAddressSetFree(priv->pciaddrs);
> -    priv->pciaddrs = NULL;
> +    if (!priv->persistentAddrs) {
> +        virDomainDefClearPCIAddresses(vm->def);
> +        qemuDomainPCIAddressSetFree(priv->pciaddrs);
> +        priv->pciaddrs = NULL;
> +    }
>  
>      qemuDomainReAttachHostDevices(driver, vm->def);
>  
> @@ -3352,6 +3417,12 @@ static virDomainPtr qemudDomainCreate(virConnectPtr conn, const char *xml,
>      if (virDomainObjIsDuplicate(&driver->domains, def, 1) < 0)
>          goto cleanup;
>  
> +    if (qemudCanonicalizeMachine(driver, def) < 0)
> +        goto cleanup;
> +
> +    if (qemuAssignPCIAddresses(def) < 0)
> +        goto cleanup;
> +
>      if (!(vm = virDomainAssignDef(driver->caps,
>                                    &driver->domains,
>                                    def)))
> @@ -5049,6 +5120,9 @@ static virDomainPtr qemudDomainDefine(virConnectPtr conn, const char *xml) {
>      if (qemudCanonicalizeMachine(driver, def) < 0)
>          goto cleanup;
>  
> +    if (qemuAssignPCIAddresses(def) < 0)
> +        goto cleanup;
> +
>      if (!(vm = virDomainAssignDef(driver->caps,
>                                    &driver->domains,
>                                    def))) {

  ACK,

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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