From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53072) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gAVYd-00035k-2n for qemu-devel@nongnu.org; Thu, 11 Oct 2018 03:38:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gAVYb-0007xk-ON for qemu-devel@nongnu.org; Thu, 11 Oct 2018 03:38:55 -0400 Received: from oxygen.pond.sub.org ([2a01:4f8:201:233:1::3]:34146) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gAVYb-0007v9-Bk for qemu-devel@nongnu.org; Thu, 11 Oct 2018 03:38:53 -0400 From: Markus Armbruster References: <20180918185246.18109-1-danielhb413@gmail.com> <20180918185246.18109-2-danielhb413@gmail.com> Date: Thu, 11 Oct 2018 09:38:49 +0200 Message-ID: <87a7nl7x12.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v9 1/3] qmp: query-current-machine with wakeup-suspend-support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Daniel Henrique Barboza Cc: qemu-devel@nongnu.org, ehabkost@redhat.com, mst@redhat.com, armbru@redhat.com, mdroth@linux.vnet.ibm.com, imammedo@redhat.com Daniel Henrique Barboza writes: > When issuing the qmp/hmp 'system_wakeup' command, what happens in a > nutshell is: > > - qmp_system_wakeup_request set runstate to RUNNING, sets a wakeup_reason > and notify the event > - in the main_loop, all vcpus are paused, a system reset is issued, all > subscribers of wakeup_notifiers receives a notification, vcpus are then > resumed and the wake up QAPI event is fired > > Note that this procedure alone doesn't ensure that the guest will awake > from SUSPENDED state - the subscribers of the wake up event must take > action to resume the guest, otherwise the guest will simply reboot. At > this moment, only the ACPI machines via acpi_pm1_cnt_init has wake-up > from suspend support. > > However, only the presence of 'system_wakeup' is required for QGA to > support 'guest-suspend-ram' and 'guest-suspend-hybrid' at this moment. > This means that the user/management will expect to suspend the guest using > one of those suspend commands and then resume execution using system_wakeup, > regardless of the support offered in system_wakeup in the first place. > > This patch creates a new API called query-current-machine [1], that holds > a new flag called 'wakeup-suspend-support' that indicates if the guest > supports wake up from suspend via system_wakeup. The machine is considered > to implement wake-up support if a call to a new 'qemu_register_wakeup_support' > is made during its init, as it is now being done inside acpi_pm1_cnt_init. > This allows for any other machine type to declare wake-up support regardless > of ACPI state or wakeup_notifiers subscription, making easier for > newer implementations that might have its own mechanisms in the future. > > This is the expected output of query-current-machine when running a x86 > guest: > > {"execute" : "query-current-machine"} > {"return": {"wakeup-suspend-support": true}} > > Running the same x86 guest, but with the --no-acpi option: > > {"execute" : "query-current-machine"} > {"return": {"wakeup-suspend-support": false}} > > This is the output when running a pseries guest: > > {"execute" : "query-current-machine"} > {"return": {"wakeup-suspend-support": false}} > > With this extra tool, management can avoid situations where a guest > that does not have proper suspend/wake capabilities ends up in > inconsistent state (e.g. > https://github.com/open-power-host-os/qemu/issues/31). > > [1] the decision of creating the query-current-machine API is based > on discussions in the QEMU mailing list where it was decided that > query-target wasn't a proper place to store the wake-up flag, neither > was query-machines because this isn't a static property of the > machine object. This new API can then be used to store other > dynamic machine properties that are scattered around the code > ATM. More info at: > https://lists.gnu.org/archive/html/qemu-devel/2018-05/msg04235.html > > Reported-by: Balamuruhan S > Signed-off-by: Daniel Henrique Barboza > --- > hw/acpi/core.c | 1 + > include/sysemu/sysemu.h | 1 + > qapi/misc.json | 24 ++++++++++++++++++++++++ > vl.c | 19 +++++++++++++++++++ > 4 files changed, 45 insertions(+) > > diff --git a/hw/acpi/core.c b/hw/acpi/core.c > index b8d39012cd..2dea893245 100644 > --- a/hw/acpi/core.c > +++ b/hw/acpi/core.c > @@ -617,6 +617,7 @@ void acpi_pm1_cnt_init(ACPIREGS *ar, MemoryRegion *parent, > ar->pm1.cnt.s4_val = s4_val; > ar->wakeup.notify = acpi_notify_wakeup; > qemu_register_wakeup_notifier(&ar->wakeup); > + qemu_register_wakeup_support(); > memory_region_init_io(&ar->pm1.cnt.io, memory_region_owner(parent), > &acpi_pm_cnt_ops, ar, "acpi-cnt", 2); > memory_region_add_subregion(parent, 4, &ar->pm1.cnt.io); We might've discussed this before, not sure... There's a second qemu_register_wakeup_notifier() in xen-hvm.c. By not adding qemu_register_wakeup_support() there, you implicitly state that it doesn't provide wakeup support. I have no idea whether that's true. If it is, then I think the commit message should explain it. We might even want a comment. Please advise. > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h > index 8d6095d98b..0446adacc6 100644 > --- a/include/sysemu/sysemu.h > +++ b/include/sysemu/sysemu.h > @@ -77,6 +77,7 @@ void qemu_register_suspend_notifier(Notifier *notifier); > void qemu_system_wakeup_request(WakeupReason reason); > void qemu_system_wakeup_enable(WakeupReason reason, bool enabled); > void qemu_register_wakeup_notifier(Notifier *notifier); > +void qemu_register_wakeup_support(void); > void qemu_system_shutdown_request(ShutdownCause reason); > void qemu_system_powerdown_request(void); > void qemu_register_powerdown_notifier(Notifier *notifier); > diff --git a/qapi/misc.json b/qapi/misc.json > index d450cfef21..b616d385a4 100644 > --- a/qapi/misc.json > +++ b/qapi/misc.json > @@ -2003,6 +2003,30 @@ > ## > { 'command': 'query-machines', 'returns': ['MachineInfo'] } > > +## > +# @CurrentMachineParams: > +# > +# Information describing the running machine parameters. > +# > +# @wakeup-suspend-support: true if the target supports wake up from s/target/machine/ > +# suspend > +# > +# Since: 3.1.0 > +## > +{ 'struct': 'CurrentMachineParams', > + 'data': { 'wakeup-suspend-support': 'bool'} } > + > +## > +# @query-current-machine: > +# > +# Return a list of parameters of the running machine. "a list of" suggests it returns a QAPI list. Let's say "Return information on the current virtual machine". > +# > +# Returns: CurrentMachineParams > +# > +# Since: 3.1.0 > +## > +{ 'command': 'query-current-machine', 'returns': 'CurrentMachineParams' } > + > ## > # @CpuDefinitionInfo: > # > diff --git a/vl.c b/vl.c > index 5ba06adf78..f78947f69c 100644 > --- a/vl.c > +++ b/vl.c > @@ -184,6 +184,7 @@ bool boot_strict; > uint8_t *boot_splash_filedata; > size_t boot_splash_filedata_size; > uint8_t qemu_extra_params_fw[2]; > +bool wakeup_suspend_enabled; > > int icount_align_option; > > @@ -1753,6 +1754,24 @@ void qemu_register_wakeup_notifier(Notifier *notifier) > notifier_list_add(&wakeup_notifiers, notifier); > } > > +void qemu_register_wakeup_support(void) > +{ > + wakeup_suspend_enabled = true; > +} > + > +static bool qemu_wakeup_suspend_enabled(void) > +{ > + return wakeup_suspend_enabled; > +} > + > +CurrentMachineParams *qmp_query_current_machine(Error **errp) > +{ > + CurrentMachineParams *params = g_malloc0(sizeof(*params)); > + params->wakeup_suspend_support = qemu_wakeup_suspend_enabled(); > + > + return params; > +} > + > void qemu_system_killed(int signal, pid_t pid) > { > shutdown_signal = signal;