Messages in this thread | | | Date | Fri, 27 Jan 2023 23:57:57 +0800 | Subject | Re: [PATCH v3 4/4] KVM: arm64: Allow no running vcpu on saving vgic3 pending table | From | Zenghui Yu <> |
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On 2023/1/27 07:54, Gavin Shan wrote: > We don't have a running VCPU context to save vgic3 pending table due > to KVM_DEV_ARM_VGIC_{GRP_CTRL, SAVE_PENDING_TABLES} command on KVM > device "kvm-arm-vgic-v3". The unknown case is caught by kvm-unit-tests. > > # ./kvm-unit-tests/tests/its-pending-migration > WARNING: CPU: 120 PID: 7973 at arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3325 \ > mark_page_dirty_in_slot+0x60/0xe0 > : > mark_page_dirty_in_slot+0x60/0xe0 > __kvm_write_guest_page+0xcc/0x100 > kvm_write_guest+0x7c/0xb0 > vgic_v3_save_pending_tables+0x148/0x2a0 > vgic_set_common_attr+0x158/0x240 > vgic_v3_set_attr+0x4c/0x5c > kvm_device_ioctl+0x100/0x160 > __arm64_sys_ioctl+0xa8/0xf0 > invoke_syscall.constprop.0+0x7c/0xd0 > el0_svc_common.constprop.0+0x144/0x160 > do_el0_svc+0x34/0x60 > el0_svc+0x3c/0x1a0 > el0t_64_sync_handler+0xb4/0x130 > el0t_64_sync+0x178/0x17c > > Use vgic_write_guest_lock() to save vgic3 pending table. > > Reported-by: Zenghui Yu <yuzenghui@huawei.com> > Signed-off-by: Gavin Shan <gshan@redhat.com> > Reviewed-by: Oliver Upton <oliver.upton@linux.dev> > --- > Documentation/virt/kvm/api.rst | 4 +++- > arch/arm64/kvm/vgic/vgic-v3.c | 2 +- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 40ada313faa3..07f07668995e 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -8074,7 +8074,9 @@ NOTE: Multiple examples of using the backup bitmap: (1) save vgic/its > tables through command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_SAVE_TABLES} on > KVM device "kvm-arm-vgic-its". (2) restore vgic/its tables through > command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_RESTORE_TABLES} on KVM device > -"kvm-arm-vgic-its". vgic3 LPI pending status is restored. > +"kvm-arm-vgic-its". vgic3 LPI pending status is restored. (3) save > +vgic3 pending table through KVM_DEV_ARM_VGIC_{GRP_CTRL, SAVE_PENDING_TABLES} > +command on KVM device "kvm-arm-vgic-v3".
Can we summarize these 3 examples with something like: "when the guest memory (pending tables, ITS tables, etc) is dirtied by the virtual GIC or ITS, which is typically triggered by a userspace request (e.g., KVM_DEV_ARM_ITS_SAVE_TABLES) and doesn't require a running VCPU context"? In case there will be more no-running-vcpu kvm_write_guest_lock() cases in the VGIC emulation code in future and we have to extend the documentation..
But I don't have objection to your writing and the whole series looks good.
Thanks, Zenghui
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