From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48563) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emk6S-00006A-0n for qemu-devel@nongnu.org; Fri, 16 Feb 2018 12:47:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1emk6N-0000vC-3w for qemu-devel@nongnu.org; Fri, 16 Feb 2018 12:47:20 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39016 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1emk6M-0000uM-TH for qemu-devel@nongnu.org; Fri, 16 Feb 2018 12:47:15 -0500 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w1GHjdfU138271 for ; Fri, 16 Feb 2018 12:47:12 -0500 Received: from e13.ny.us.ibm.com (e13.ny.us.ibm.com [129.33.205.203]) by mx0b-001b2d01.pphosted.com with ESMTP id 2g63hrrx70-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 16 Feb 2018 12:47:11 -0500 Received: from localhost by e13.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 16 Feb 2018 12:47:11 -0500 References: <20180105130314.26026-1-danielhb@linux.vnet.ibm.com> <20180105130314.26026-2-danielhb@linux.vnet.ibm.com> <151872925836.9327.9182686871344891193@sif> From: Daniel Henrique Barboza Date: Fri, 16 Feb 2018 15:47:06 -0200 MIME-Version: 1.0 In-Reply-To: <151872925836.9327.9182686871344891193@sif> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Message-Id: <49bbb9cd-6ee0-ab8a-599d-27daa62538b7@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [PATCH v4 1/2] qmp: adding 'wakeup-suspend-support' in query-target List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Roth , qemu-devel@nongnu.org Cc: armbru@redhat.com, dgilbert@redhat.com On 02/15/2018 07:14 PM, Michael Roth wrote: > Quoting Daniel Henrique Barboza (2018-01-05 07:03:13) >> 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 there are only two subscribers of the wake up event: one >> in hw/acpi/core.c and another one in hw/i386/xen/xen-hvm.c. This means >> that system_wakeup does not work as intended with other architectures. >> >> 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 adds a new flag called 'wakeup-suspend-support' in TargetInfo >> that allows the caller to query if the guest supports wake up from >> suspend via system_wakeup. It goes over the subscribers of the wake up >> event and, if it's empty, it assumes that the guest does not support >> wake up from suspend (and thus, pm-suspend itself). >> >> This is the expected output of query-target when running a x86 guest: >> >> {"execute" : "query-target"} >> {"return": {"arch": "x86_64", "wakeup-suspend-support": true}} >> >> This is the output when running a pseries guest: >> >> {"execute" : "query-target"} >> {"return": {"arch": "ppc64", "wakeup-suspend-support": false}} >> >> Given that the TargetInfo structure is read-only, adding a new flag to >> it is backwards compatible. There is no need to deprecate the old >> TargetInfo format. >> >> 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). >> >> Signed-off-by: Daniel Henrique Barboza >> --- >> arch_init.c | 1 + >> include/sysemu/sysemu.h | 1 + >> qapi-schema.json | 4 +++- >> vl.c | 29 +++++++++++++++++++++++++++++ >> 4 files changed, 34 insertions(+), 1 deletion(-) >> >> diff --git a/arch_init.c b/arch_init.c >> index a0b8ed6167..9c5c519d9d 100644 >> --- a/arch_init.c >> +++ b/arch_init.c >> @@ -109,6 +109,7 @@ TargetInfo *qmp_query_target(Error **errp) >> TargetInfo *info = g_malloc0(sizeof(*info)); >> >> info->arch = g_strdup(TARGET_NAME); >> + info->wakeup_suspend_support = !qemu_wakeup_notifier_is_empty(); >> >> return info; >> } >> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h >> index 31612caf10..b15374e0b8 100644 >> --- a/include/sysemu/sysemu.h >> +++ b/include/sysemu/sysemu.h >> @@ -69,6 +69,7 @@ typedef enum WakeupReason { >> void qemu_system_reset_request(ShutdownCause reason); >> void qemu_system_suspend_request(void); >> void qemu_register_suspend_notifier(Notifier *notifier); >> +bool qemu_wakeup_notifier_is_empty(void); >> void qemu_system_wakeup_request(WakeupReason reason); >> void qemu_system_wakeup_enable(WakeupReason reason, bool enabled); >> void qemu_register_wakeup_notifier(Notifier *notifier); >> diff --git a/qapi-schema.json b/qapi-schema.json >> index 5c06745c79..2f1c08fde7 100644 >> --- a/qapi-schema.json >> +++ b/qapi-schema.json >> @@ -2388,11 +2388,13 @@ >> # Information describing the QEMU target. >> # >> # @arch: the target architecture (eg "x86_64", "i386", etc) >> +# @wakeup-suspend-support: true if the target supports wake up from >> +# suspend (since 2.12) >> # >> # Since: 1.2.0 >> ## >> { 'struct': 'TargetInfo', >> - 'data': { 'arch': 'str' } } >> + 'data': { 'arch': 'str', 'wakeup-suspend-support': 'bool' } } >> >> ## >> # @query-target: >> diff --git a/vl.c b/vl.c >> index d3a5c5d021..56d6a1ce5b 100644 >> --- a/vl.c >> +++ b/vl.c >> @@ -1839,11 +1839,40 @@ void qemu_system_wakeup_enable(WakeupReason reason, bool enabled) >> } >> } >> >> +/* The existence of a wake-up notifier is being checked in the function >> + * qemu_wakeup_notifier_is_empty and it's used in the logic of the >> + * wakeup-suspend-support flag of QMP 'query-target' command. The idea >> + * of this flag is to indicate whether the guest supports wake-up from >> + * suspend (via system_wakeup QMP/HMP call for example), warning the user >> + * that the guest can't handle both wake-up from suspend and the suspend >> + * itself via QGA guest-suspend-ram and guest-suspend-hybrid (if it >> + * can't wake up, it can't be suspended safely). >> + * >> + * The motivation of this design is that this notification will only >> + * fire if a wake up attempt is made by qemu_system_wakeup_request and >> + * the current runstate is RUN_STATE_SUSPENDED. This run state is set by >> + * qemu_system_suspend_request, which at this moment is only being >> + * called in hw/acpi/core.c. This means that, today, only ACPI implements >> + * the proper suspend support and can successfully execute both >> + * guest-suspend-(ram/hybrid) and system_wakeup. >> + * > I think something like the below paragraph gets the important stuff across well > enough; the implementation/design details above make it a bit harder to quickly > grok what's going here (for me at least) and would need to be updated if > new users implement full suspend/wakeup. > > Looks good otherwise. Thanks for the review Mike! I'll respin this series without that "motivation" paragraph. Daniel > >> + * Thus, an assumption is made by the wakeup-suspend-support flag that >> + * only the guests that can go to RUN_STATE_SUSPENDED and wake up properly >> + * would be interested in this wakeup_notifier. Adding a wakeup_notifier >> + * for any other reason will break the logic of the wakeup-suspend-support >> + * flag and can lead to user/management confusion about the suspend/wake-up >> + * support of the guest. >> + */ >> void qemu_register_wakeup_notifier(Notifier *notifier) >> { >> notifier_list_add(&wakeup_notifiers, notifier); >> } >> >> +bool qemu_wakeup_notifier_is_empty(void) >> +{ >> + return QLIST_EMPTY(&wakeup_notifiers.notifiers); >> +} >> + >> void qemu_system_killed(int signal, pid_t pid) >> { >> shutdown_signal = signal; >> -- >> 2.13.6 >> >