From: Eric Blake <eblake@redhat.com> To: Ashish Kalra <Ashish.Kalra@amd.com> Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, ehabkost@redhat.com, mst@redhat.com, richard.henderson@linaro.org, jejb@linux.ibm.com, tobin@ibm.com, dovmurik@linux.vnet.ibm.com, frankeh@us.ibm.com, dgilbert@redhat.com, kvm@vger.kernel.org Subject: Re: [RFC PATCH 01/13] machine: Add mirrorvcpus=N suboption to -smp Date: Mon, 16 Aug 2021 16:23:14 -0500 [thread overview] Message-ID: <20210816212314.kxpbo2sfoxkzliwt@redhat.com> (raw) In-Reply-To: <235c91b1b09f11c75bfc60597938c97d3ebb0861.1629118207.git.ashish.kalra@amd.com> On Mon, Aug 16, 2021 at 01:26:45PM +0000, Ashish Kalra wrote: > From: Dov Murik <dovmurik@linux.vnet.ibm.com> > > Add a notion of mirror vcpus to CpuTopology, which will allow to > designate a few vcpus (normally 1) for running the guest > migration handler (MH). > > Example usage for starting a 4-vcpu guest, of which 1 vcpu is marked as > mirror vcpu. > > qemu-system-x86_64 -smp 4,mirrorvcpus=1 ... > > Signed-off-by: Dov Murik <dovmurik@linux.vnet.ibm.com> > Co-developed-by: Ashish Kalra <ashish.kalra@amd.com> > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > --- > +++ b/qapi/machine.json > @@ -1303,6 +1303,8 @@ > # > # @maxcpus: maximum number of hotpluggable virtual CPUs in the virtual machine > # > +# @mirrorvcpus: maximum number of mirror virtual CPUs in the virtual machine > +# Needs a '(since 6.2)' tag. > # Since: 6.1 > ## > { 'struct': 'SMPConfiguration', 'data': { > @@ -1311,4 +1313,5 @@ > '*dies': 'int', > '*cores': 'int', > '*threads': 'int', > - '*maxcpus': 'int' } } > + '*maxcpus': 'int', > + '*mirrorvcpus': 'int' } } Is this really the right place to be adding it? The rest of this struct feels like things that advertise what bare metal can do, and therefore what we are emulating. But bare metal can't do mirrors - that's something that is completely in the realm of emulation only. If I understand the cover letter, the guest shouldn't be able to detect that mirroring exists, which is different from how the guest DOES detect how many dies, cores, and threads are available to use. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
WARNING: multiple messages have this Message-ID (diff)
From: Eric Blake <eblake@redhat.com> To: Ashish Kalra <Ashish.Kalra@amd.com> Cc: thomas.lendacky@amd.com, brijesh.singh@amd.com, ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com, tobin@ibm.com, jejb@linux.ibm.com, richard.henderson@linaro.org, qemu-devel@nongnu.org, dgilbert@redhat.com, frankeh@us.ibm.com, dovmurik@linux.vnet.ibm.com, pbonzini@redhat.com Subject: Re: [RFC PATCH 01/13] machine: Add mirrorvcpus=N suboption to -smp Date: Mon, 16 Aug 2021 16:23:14 -0500 [thread overview] Message-ID: <20210816212314.kxpbo2sfoxkzliwt@redhat.com> (raw) In-Reply-To: <235c91b1b09f11c75bfc60597938c97d3ebb0861.1629118207.git.ashish.kalra@amd.com> On Mon, Aug 16, 2021 at 01:26:45PM +0000, Ashish Kalra wrote: > From: Dov Murik <dovmurik@linux.vnet.ibm.com> > > Add a notion of mirror vcpus to CpuTopology, which will allow to > designate a few vcpus (normally 1) for running the guest > migration handler (MH). > > Example usage for starting a 4-vcpu guest, of which 1 vcpu is marked as > mirror vcpu. > > qemu-system-x86_64 -smp 4,mirrorvcpus=1 ... > > Signed-off-by: Dov Murik <dovmurik@linux.vnet.ibm.com> > Co-developed-by: Ashish Kalra <ashish.kalra@amd.com> > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > --- > +++ b/qapi/machine.json > @@ -1303,6 +1303,8 @@ > # > # @maxcpus: maximum number of hotpluggable virtual CPUs in the virtual machine > # > +# @mirrorvcpus: maximum number of mirror virtual CPUs in the virtual machine > +# Needs a '(since 6.2)' tag. > # Since: 6.1 > ## > { 'struct': 'SMPConfiguration', 'data': { > @@ -1311,4 +1313,5 @@ > '*dies': 'int', > '*cores': 'int', > '*threads': 'int', > - '*maxcpus': 'int' } } > + '*maxcpus': 'int', > + '*mirrorvcpus': 'int' } } Is this really the right place to be adding it? The rest of this struct feels like things that advertise what bare metal can do, and therefore what we are emulating. But bare metal can't do mirrors - that's something that is completely in the realm of emulation only. If I understand the cover letter, the guest shouldn't be able to detect that mirroring exists, which is different from how the guest DOES detect how many dies, cores, and threads are available to use. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
next prev parent reply other threads:[~2021-08-16 21:23 UTC|newest] Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-16 13:25 [RFC PATCH 00/13] Add support for Mirror VM Ashish Kalra 2021-08-16 13:26 ` [RFC PATCH 01/13] machine: Add mirrorvcpus=N suboption to -smp Ashish Kalra 2021-08-16 21:23 ` Eric Blake [this message] 2021-08-16 21:23 ` Eric Blake 2021-08-16 13:27 ` [RFC PATCH 02/13] hw/boards: Add mirror_vcpu flag to CPUArchId Ashish Kalra 2021-08-16 13:27 ` [RFC PATCH 03/13] hw/i386: Mark mirror vcpus in possible_cpus Ashish Kalra 2021-08-16 13:27 ` [RFC PATCH 04/13] hw/acpi: Don't include mirror vcpus in ACPI tables Ashish Kalra 2021-08-16 13:28 ` [RFC PATCH 05/13] cpu: Add boolean mirror_vcpu field to CPUState Ashish Kalra 2021-08-16 13:28 ` [RFC PATCH 06/13] hw/i386: Set CPUState.mirror_vcpu=true for mirror vcpus Ashish Kalra 2021-08-16 13:29 ` [RFC PATCH 07/13] kvm: Add Mirror VM ioctl and enable cap interfaces Ashish Kalra 2021-08-16 13:29 ` [RFC PATCH 08/13] kvm: Add Mirror VM support Ashish Kalra 2021-08-16 13:29 ` [RFC PATCH 09/13] kvm: create Mirror VM and share primary VM's encryption context Ashish Kalra 2021-08-16 13:30 ` [RFC PATCH 10/13] softmmu/cpu: Skip mirror vcpu's for pause, resume and synchronization Ashish Kalra 2021-08-16 13:30 ` [RFC PATCH 11/13] kvm/apic: Disable in-kernel APIC support for mirror vcpu's Ashish Kalra 2021-08-16 13:31 ` [RFC PATCH 12/13] hw/acpi: disable modern CPU hotplug interface " Ashish Kalra 2021-08-16 13:31 ` [RFC PATCH 13/13] hw/i386/pc: reduce fw_cfg boot cpu count taking into account " Ashish Kalra 2021-08-16 14:01 ` [RFC PATCH 00/13] Add support for Mirror VM Claudio Fontana 2021-08-16 14:01 ` Claudio Fontana 2021-08-16 14:15 ` Paolo Bonzini 2021-08-16 14:15 ` Paolo Bonzini 2021-08-16 14:23 ` Daniel P. Berrangé 2021-08-16 14:23 ` Daniel P. Berrangé 2021-08-16 15:00 ` Paolo Bonzini 2021-08-16 15:00 ` Paolo Bonzini 2021-08-16 15:16 ` Daniel P. Berrangé 2021-08-16 15:16 ` Daniel P. Berrangé 2021-08-16 15:35 ` Paolo Bonzini 2021-08-16 15:35 ` Paolo Bonzini 2021-08-16 14:44 ` Ashish Kalra 2021-08-16 14:58 ` Paolo Bonzini 2021-08-16 14:58 ` Paolo Bonzini 2021-08-16 15:13 ` Ashish Kalra 2021-08-16 15:38 ` Paolo Bonzini 2021-08-16 15:38 ` Paolo Bonzini 2021-08-16 15:48 ` Dr. David Alan Gilbert 2021-08-16 15:48 ` Dr. David Alan Gilbert 2021-08-18 10:31 ` Ashish Kalra 2021-08-18 11:25 ` James Bottomley 2021-08-18 11:25 ` James Bottomley 2021-08-18 15:31 ` Dr. David Alan Gilbert 2021-08-18 15:31 ` Dr. David Alan Gilbert 2021-08-18 15:35 ` James Bottomley 2021-08-18 15:35 ` James Bottomley 2021-08-18 15:43 ` Dr. David Alan Gilbert 2021-08-18 15:43 ` Dr. David Alan Gilbert 2021-08-18 16:28 ` James Bottomley 2021-08-18 16:28 ` James Bottomley 2021-08-18 17:30 ` Dr. David Alan Gilbert 2021-08-18 17:30 ` Dr. David Alan Gilbert 2021-08-18 18:51 ` James Bottomley 2021-08-18 18:51 ` James Bottomley 2021-08-18 19:47 ` Paolo Bonzini 2021-08-16 17:23 ` Dr. David Alan Gilbert 2021-08-16 17:23 ` Dr. David Alan Gilbert 2021-08-16 20:53 ` Paolo Bonzini 2021-08-16 23:53 ` Steve Rutherford 2021-08-16 23:53 ` Steve Rutherford 2021-08-17 7:05 ` Michael S. Tsirkin 2021-08-17 7:05 ` Michael S. Tsirkin 2021-08-17 8:38 ` Dr. David Alan Gilbert 2021-08-17 8:38 ` Dr. David Alan Gilbert 2021-08-17 14:08 ` Ashish Kalra 2021-08-17 16:32 ` Paolo Bonzini 2021-08-17 16:32 ` Paolo Bonzini 2021-08-17 20:50 ` Tobin Feldman-Fitzthum 2021-08-17 20:50 ` Tobin Feldman-Fitzthum 2021-08-17 22:04 ` Steve Rutherford 2021-08-17 22:04 ` Steve Rutherford 2021-08-18 15:32 ` Tobin Feldman-Fitzthum 2021-08-18 15:32 ` Tobin Feldman-Fitzthum 2021-08-18 19:04 ` Dr. David Alan Gilbert 2021-08-18 19:04 ` Dr. David Alan Gilbert 2021-08-18 21:42 ` Tobin Feldman-Fitzthum 2021-08-18 21:42 ` Tobin Feldman-Fitzthum 2021-08-19 8:22 ` Dr. David Alan Gilbert 2021-08-19 8:22 ` Dr. David Alan Gilbert 2021-08-19 14:06 ` James Bottomley 2021-08-19 14:06 ` James Bottomley 2021-08-19 14:28 ` Dr. David Alan Gilbert 2021-08-19 14:28 ` Dr. David Alan Gilbert 2021-08-19 22:10 ` James Bottomley 2021-08-19 22:10 ` James Bottomley 2021-08-23 12:26 ` Dr. David Alan Gilbert 2021-08-23 12:26 ` Dr. David Alan Gilbert 2021-08-23 16:28 ` Tobin Feldman-Fitzthum 2021-08-23 16:28 ` Tobin Feldman-Fitzthum 2021-08-19 14:07 ` Tobin Feldman-Fitzthum 2021-08-19 14:07 ` Tobin Feldman-Fitzthum 2021-08-17 23:20 ` Paolo Bonzini 2021-08-17 23:20 ` Paolo Bonzini 2021-08-17 21:54 ` Steve Rutherford 2021-08-17 21:54 ` Steve Rutherford 2021-08-17 22:37 ` Paolo Bonzini 2021-08-17 22:37 ` Paolo Bonzini 2021-08-17 22:57 ` James Bottomley 2021-08-17 22:57 ` James Bottomley 2021-08-17 23:10 ` Steve Rutherford 2021-08-17 23:10 ` Steve Rutherford 2021-08-18 2:49 ` James Bottomley 2021-08-18 2:49 ` James Bottomley 2021-08-18 14:06 ` Ashish Kalra 2021-08-18 17:07 ` Ashish Kalra
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