lkml.org 
[lkml]   [2023]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v3 4/4] KVM: arm64: Allow no running vcpu on saving vgic3 pending table
    From
    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

    \
     
     \ /
      Last update: 2023-03-26 23:58    [W:8.523 / U:0.148 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site