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Thu, 16 May 2019 14:17:52 +0000 (UTC) Received: from work-vm (unknown [10.36.118.12]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 406BF5D9CD; Thu, 16 May 2019 14:17:49 +0000 (UTC) Date: Thu, 16 May 2019 15:17:47 +0100 From: "Dr. David Alan Gilbert" To: Aravinda Prasad Message-ID: <20190516141746.GB3005@work-vm> References: <155591636364.20338.844048953355207313.stgit@aravinda> <155591662496.20338.3862565585716109724.stgit@aravinda> <20190516125445.79d0ba34@bahia.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 16 May 2019 14:17:53 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH v8 6/6] migration: Block migration while handling machine check X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: aik@au1.ibm.com, Greg Kurz , qemu-devel@nongnu.org, paulus@ozlabs.org, qemu-ppc@nongnu.org, david@gibson.dropbear.id.au Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Aravinda Prasad (aravinda@linux.vnet.ibm.com) wrote: > > > On Thursday 16 May 2019 04:24 PM, Greg Kurz wrote: > > On Mon, 22 Apr 2019 12:33:45 +0530 > > Aravinda Prasad wrote: > > > >> Block VM migration requests until the machine check > >> error handling is complete as (i) these errors are > >> specific to the source hardware and is irrelevant on > >> the target hardware, (ii) these errors cause data > >> corruption and should be handled before migration. > >> > >> Signed-off-by: Aravinda Prasad > >> --- > >> hw/ppc/spapr_events.c | 17 +++++++++++++++++ > >> hw/ppc/spapr_rtas.c | 4 ++++ > >> include/hw/ppc/spapr.h | 3 +++ > >> 3 files changed, 24 insertions(+) > >> > >> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c > >> index 4032db0..45b990c 100644 > >> --- a/hw/ppc/spapr_events.c > >> +++ b/hw/ppc/spapr_events.c > >> @@ -41,6 +41,7 @@ > >> #include "qemu/bcd.h" > >> #include "hw/ppc/spapr_ovec.h" > >> #include > >> +#include "migration/blocker.h" > >> > >> #define RTAS_LOG_VERSION_MASK 0xff000000 > >> #define RTAS_LOG_VERSION_6 0x06000000 > >> @@ -864,6 +865,22 @@ static void spapr_mce_dispatch_elog(PowerPCCPU *cpu, bool recovered) > >> void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered) > >> { > >> SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine()); > >> + int ret; > >> + Error *local_err = NULL; > >> + > >> + error_setg(&spapr->migration_blocker, > >> + "Live migration not supported during machine check handling"); > >> + ret = migrate_add_blocker(spapr->migration_blocker, &local_err); > > > > migrate_add_blocker() propagates the reason of the failure in local_err, > > ie. because a migration is already in progress or --only-migratable was > > passed on the QEMU command line, along with the error message passed in > > the first argument. This means that... > > > >> + if (ret < 0) { > >> + /* > >> + * We don't want to abort and let the migration to continue. In a > >> + * rare case, the machine check handler will run on the target > >> + * hardware. Though this is not preferable, it is better than aborting > >> + * the migration or killing the VM. > >> + */ > >> + error_free(spapr->migration_blocker); > >> + fprintf(stderr, "Warning: Machine check during VM migration\n"); > > > > ... you should just do: > > > > error_report_err(local_err); > > > > This also takes care of freeing local_err which would be leaked otherwise. > > Sure. I am planning to use warn_report_err() as I don't want to abort. I worry what the high level effect of this blocker will be. Since failing hardware is a common reason for wanting to do a migrate I worry that if the hardware is reporting lots of errors you might not be able to migrate the VM to more solid hardware because of this blocker. Dave > Regards, > Aravinda > > > > >> + } > >> > >> while (spapr->mc_status != -1) { > >> /* > >> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c > >> index 997cf19..1229a0e 100644 > >> --- a/hw/ppc/spapr_rtas.c > >> +++ b/hw/ppc/spapr_rtas.c > >> @@ -50,6 +50,7 @@ > >> #include "target/ppc/mmu-hash64.h" > >> #include "target/ppc/mmu-book3s-v3.h" > >> #include "kvm_ppc.h" > >> +#include "migration/blocker.h" > >> > >> static void rtas_display_character(PowerPCCPU *cpu, SpaprMachineState *spapr, > >> uint32_t token, uint32_t nargs, > >> @@ -396,6 +397,9 @@ static void rtas_ibm_nmi_interlock(PowerPCCPU *cpu, > >> spapr->mc_status = -1; > >> qemu_cond_signal(&spapr->mc_delivery_cond); > >> rtas_st(rets, 0, RTAS_OUT_SUCCESS); > >> + migrate_del_blocker(spapr->migration_blocker); > >> + error_free(spapr->migration_blocker); > >> + spapr->migration_blocker = NULL; > >> } > >> } > >> > >> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h > >> index 9d16ad1..dda5fd2 100644 > >> --- a/include/hw/ppc/spapr.h > >> +++ b/include/hw/ppc/spapr.h > >> @@ -10,6 +10,7 @@ > >> #include "hw/ppc/spapr_irq.h" > >> #include "hw/ppc/spapr_xive.h" /* For SpaprXive */ > >> #include "hw/ppc/xics.h" /* For ICSState */ > >> +#include "qapi/error.h" > >> > >> struct SpaprVioBus; > >> struct SpaprPhbState; > >> @@ -213,6 +214,8 @@ struct SpaprMachineState { > >> SpaprCapabilities def, eff, mig; > >> > >> unsigned gpu_numa_id; > >> + > >> + Error *migration_blocker; > >> }; > >> > >> #define H_SUCCESS 0 > >> > >> > > > > -- > Regards, > Aravinda > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK