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From: Gavin Shan <gshan@redhat.com>
To: kvmarm@lists.linux.dev
Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, pbonzini@redhat.com,
	maz@kernel.org, corbet@lwn.net, james.morse@arm.com,
	suzuki.poulose@arm.com, oliver.upton@linux.dev,
	yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org,
	ricarkol@google.com, eric.auger@redhat.com, yuzhe@nfschina.com,
	renzhengeek@gmail.com, ardb@kernel.org, peterx@redhat.com,
	seanjc@google.com, shan.gavin@gmail.com
Subject: [PATCH 2/4] KVM: arm64: Allow saving vgic3 pending tables in no running vcpu context
Date: Mon, 16 Jan 2023 12:04:03 +0800	[thread overview]
Message-ID: <20230116040405.260935-3-gshan@redhat.com> (raw)
In-Reply-To: <20230116040405.260935-1-gshan@redhat.com>

It's possible to save vgic3 pending tables in no running VCPU
context. This is another unknown case detected 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

Fix it by allowing to save VGIC3 pending tables in no running VCPU
context.

Reported-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 Documentation/virt/kvm/api.rst | 3 +++
 arch/arm64/kvm/vgic/vgic-v3.c  | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 18b245a0ba02..7cf3d4b77703 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8074,6 +8074,9 @@ NOTE: One example of using the backup bitmap is saving arm64 vgic/its
 tables and vgic3 LPI pending status through KVM_DEV_ARM_{VGIC_GRP_CTRL,
 ITS_SAVE_TABLES} and KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_RESTORE_TABLES}
 command on KVM device "kvm-arm-vgic-its" when dirty ring is enabled.
+The backup bitmap is also used when vgic3 pending table is saved
+through KVM_DEV_ARM_{VGIC_GRP_CTRL, VGIC_SAVE_PENDING_TABLES} command
+on KVM device "kvm-arm-vgic-v3".
 
 8.30 KVM_CAP_XEN_HVM
 --------------------
diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
index 32998c8587a8..1e6b5f19d524 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -440,7 +440,9 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
 		else
 			val &= ~(1 << bit_nr);
 
+		dist->save_vgic_v3_tables_in_progress = true;
 		ret = kvm_write_guest_lock(kvm, ptr, &val, 1);
+		dist->save_vgic_v3_tables_in_progress = false;
 		if (ret)
 			goto out;
 	}
-- 
2.23.0


  parent reply	other threads:[~2023-01-16  4:05 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-16  4:04 [PATCH 0/4] Improve dirty ring warning report Gavin Shan
2023-01-16  4:04 ` [PATCH 1/4] KVM: arm64: Allow saving vgic3 LPI pending status in no running vcpu context Gavin Shan
2023-01-17 20:51   ` Oliver Upton
2023-01-19  1:11     ` Gavin Shan
2023-01-19 15:47       ` Marc Zyngier
2023-01-19 23:04         ` Gavin Shan
2023-01-16  4:04 ` Gavin Shan [this message]
2023-01-16  4:04 ` [PATCH 3/4] KVM: Refactor mark_page_dirty_in_slot() Gavin Shan
2023-01-16  4:04 ` [PATCH 4/4] KVM: Improve warning report in mark_page_dirty_in_slot() Gavin Shan
2023-01-17 15:42   ` Sean Christopherson
2023-01-19  1:15     ` Gavin Shan
2023-01-19 15:19       ` Sean Christopherson
2023-01-19 23:06         ` Gavin Shan

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