On Thu, Sep 21, 2017 at 16:47:08 +0200, Michal Privoznik wrote:
> In the near future the qemuAssignDeviceAliases() function is
> going to be called multiple times: once at the domain define
> time, then in domain prepare phase. To avoid regenerating the
> same aliases the second time we need to be able to tell the
> function which time it is being called.
>
> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
> ---
> src/qemu/qemu_alias.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++--
> src/qemu/qemu_alias.h | 4 +-
> src/qemu/qemu_driver.c | 2 +-
> src/qemu/qemu_process.c | 2 +-
> tests/qemuhotplugtest.c | 2 +-
> 5 files changed, 115 insertions(+), 8 deletions(-)
>
> diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c
> index e1431e2a2..00868c50f 100644
> --- a/src/qemu/qemu_alias.c
> +++ b/src/qemu/qemu_alias.c
> @@ -481,25 +481,99 @@ qemuAssignDeviceShmemAlias(virDomainDefPtr def,
> }
>
>
> +/*
> + * qemuAssignDeviceAliases:
> + * @def: domain definition
> + * @qemuCaps: qemu capabilities
> + * @regenerate: forcibly regenerate aliases
> + *
> + * Assign aliases to domain devices. If @regenerate is false only
> + * the missing aliases are generated leaving already assigned
> + * aliases untouched. If @regenerate is true any preexisting
> + * aliases are overwritten.
> + *
> + * Returns 0 on success, -1 otherwise.
> + */
> int
> -qemuAssignDeviceAliases(virDomainDefPtr def, virQEMUCapsPtr qemuCaps)
> +qemuAssignDeviceAliases(virDomainDefPtr def,
> + virQEMUCapsPtr qemuCaps,
> + bool regenerate)
> {
> size_t i;
>
> + if (regenerate) {
> + /* If we need to regenerate the aliases, we have to free
> + * them all upfront because there are some dependencies,
> + * e.g. an interface can be a hostdev and so on.
> + * Therefore, if we'd do the freeing in the loop below we
> + * might not start from zero. */
> + for (i = 0; i < def->ndisks; i++)
> + VIR_FREE(def->disks[i]->info.alias);
> + for (i = 0; i < def->nnets; i++)
> + VIR_FREE(def->nets[i]->info.alias);
> + for (i = 0; i < def->nfss; i++)
> + VIR_FREE(def->fss[i]->info.alias);
> + for (i = 0; i < def->nsounds; i++)
> + VIR_FREE(def->sounds[i]->info.alias);
> + for (i = 0; i < def->nhostdevs; i++)
> + VIR_FREE(def->hostdevs[i]->info->alias);
> + for (i = 0; i < def->nredirdevs; i++)
> + VIR_FREE(def->redirdevs[i]->info.alias);
> + for (i = 0; i < def->nvideos; i++)
> + VIR_FREE(def->videos[i]->info.alias);
> + for (i = 0; i < def->ncontrollers; i++)
> + VIR_FREE(def->controllers[i]->info.alias);
> + for (i = 0; i < def->ninputs; i++)
> + VIR_FREE(def->inputs[i]->info.alias);
> + for (i = 0; i < def->nparallels; i++)
> + VIR_FREE(def->parallels[i]->info.alias);
> + for (i = 0; i < def->nserials; i++)
> + VIR_FREE(def->serials[i]->info.alias);
> + for (i = 0; i < def->nchannels; i++)
> + VIR_FREE(def->channels[i]->info.alias);
> + for (i = 0; i < def->nconsoles; i++)
> + VIR_FREE(def->consoles[i]->info.alias);
> + for (i = 0; i < def->nhubs; i++)
> + VIR_FREE(def->hubs[i]->info.alias);
> + for (i = 0; i < def->nshmems; i++)
> + VIR_FREE(def->shmems[i]->info.alias);
> + for (i = 0; i < def->nsmartcards; i++)
> + VIR_FREE(def->smartcards[i]->info.alias);
> + if (def->watchdog)
> + VIR_FREE(def->watchdog->info.alias);
> + if (def->memballoon)
> + VIR_FREE(def->memballoon->info.alias);
> + for (i = 0; i < def->nrngs; i++)
> + VIR_FREE(def->rngs[i]->info.alias);
> + if (def->tpm)
> + VIR_FREE(def->tpm->info.alias);
> + for (i = 0; i < def->nmems; i++)
> + VIR_FREE(def->mems[i]->info.alias);
> + }
> +
> +
> for (i = 0; i < def->ndisks; i++) {
> + if (def->disks[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceDiskAlias(def, def->disks[i], qemuCaps) < 0)
> return -1;
> }
> for (i = 0; i < def->nnets; i++) {
> + if (def->nets[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceNetAlias(def, def->nets[i], -1) < 0)
> return -1;
> }
>
> for (i = 0; i < def->nfss; i++) {
> + if (def->fss[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceFSAlias(def->fss[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nsounds; i++) {
> + if (def->sounds[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceSoundAlias(def->sounds[i], i) < 0)
> return -1;
> }
> @@ -509,71 +583,102 @@ qemuAssignDeviceAliases(virDomainDefPtr def, virQEMUCapsPtr qemuCaps)
> * linked to a NetDef, they will share an info and the alias
> * will already be set, so don't try to set it again.
> */
> + if (def->hostdevs[i]->info->alias && !regenerate)
> + continue;
> if (!def->hostdevs[i]->info->alias &&
> qemuAssignDeviceHostdevAlias(def, &def->hostdevs[i]->info->alias, -1) < 0)
> return -1;
> }
> for (i = 0; i < def->nredirdevs; i++) {
> + if (def->redirdevs[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceRedirdevAlias(def, def->redirdevs[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nvideos; i++) {
> + if (def->videos[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceVideoAlias(def->videos[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->ncontrollers; i++) {
> + if (def->controllers[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceControllerAlias(def, qemuCaps, def->controllers[i]) < 0)
> return -1;
> }
> for (i = 0; i < def->ninputs; i++) {
> + if (def->inputs[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceInputAlias(def->inputs[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nparallels; i++) {
> + if (def->parallels[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceChrAlias(def, def->parallels[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nserials; i++) {
> + if (def->serials[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceChrAlias(def, def->serials[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nchannels; i++) {
> + if (def->channels[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceChrAlias(def, def->channels[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nconsoles; i++) {
> + if (def->consoles[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceChrAlias(def, def->consoles[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nhubs; i++) {
> + if (def->hubs[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceHubAlias(def->hubs[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nshmems; i++) {
> + if (def->shmems[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceShmemAlias(def, def->shmems[i], i) < 0)
> return -1;
> }
> for (i = 0; i < def->nsmartcards; i++) {
> + if (def->smartcards[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceSmartcardAlias(def->smartcards[i], i) < 0)
> return -1;
> }
> - if (def->watchdog) {
> + if (def->watchdog &&
> + (!def->watchdog->info.alias || regenerate)) {
> if (qemuAssignDeviceWatchdogAlias(def->watchdog, 0) < 0)
> return -1;
> }
> - if (def->memballoon) {
> + if (def->memballoon &&
> + (!def->memballoon->info.alias || regenerate)) {
> if (qemuAssingDeviceMemballoonAlias(def->memballoon, 0) < 0)
> return -1;
> }
> for (i = 0; i < def->nrngs; i++) {
> + if (def->rngs[i]->info.alias && !regenerate)
> + continue;
> if (qemuAssignDeviceRNGAlias(def, def->rngs[i], i) < 0)
> return -1;
> }
So if you want to make aliases persistent, at least this will not work
properly with device coldplug.
If you have two devices, detach the first one, then the second one moves
to index 0 but will still have alias ending with 1. Then if you cold-add
another device that will be put into index 1, and when starting the VM
it will get assigned the same alias as the one which has the old one.
This applies to all devices where the alias depends on the ordering.
Additionally this series specifically does not assign aliases for
coldplugged devices so there's a discrepancy between when defining a XML
and modifying it with the APIs which should not really be the case.
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