Hi Marc,
On 11/7/22 5:47 PM, Marc Zyngier wrote:
On Sun, 06 Nov 2022 21:46:19 +0000,
Gavin Shan <gshan@xxxxxxxxxx> wrote:
On 11/6/22 11:50 PM, Marc Zyngier wrote:
On Fri, 04 Nov 2022 23:40:46 +0000,
Gavin Shan <gshan@xxxxxxxxxx> wrote:
Enable ring-based dirty memory tracking on arm64 by selecting
CONFIG_HAVE_KVM_DIRTY_{RING_ACQ_REL, RING_WITH_BITMAP} and providing
the ring buffer's physical page offset (KVM_DIRTY_LOG_PAGE_OFFSET).
Besides, helper kvm_vgic_save_its_tables_in_progress() is added to
indicate if vgic/its tables are being saved or not. The helper is used
in ARM64's kvm_arch_allow_write_without_running_vcpu() to keep the
site of saving vgic/its tables out of no-running-vcpu radar.
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 2 +-
arch/arm64/include/uapi/asm/kvm.h | 1 +
arch/arm64/kvm/Kconfig | 2 ++
arch/arm64/kvm/arm.c | 3 +++
arch/arm64/kvm/mmu.c | 15 +++++++++++++++
arch/arm64/kvm/vgic/vgic-its.c | 3 +++
arch/arm64/kvm/vgic/vgic-mmio-v3.c | 7 +++++++
include/kvm/arm_vgic.h | 2 ++
8 files changed, 34 insertions(+), 1 deletion(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 2ec32bd41792..2fc68f684ad8 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -7921,7 +7921,7 @@ regardless of what has actually been exposed through the CPUID leaf.
8.29 KVM_CAP_DIRTY_LOG_RING/KVM_CAP_DIRTY_LOG_RING_ACQ_REL
----------------------------------------------------------
-:Architectures: x86
+:Architectures: x86, arm64
:Parameters: args[0] - size of the dirty log ring
KVM is capable of tracking dirty memory using ring buffers that
are
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..a7a857f1784d 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -43,6 +43,7 @@
#define __KVM_HAVE_VCPU_EVENTS
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
+#define KVM_DIRTY_LOG_PAGE_OFFSET 64
#define KVM_REG_SIZE(id)
\
(1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 815cc118c675..066b053e9eb9 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -32,6 +32,8 @@ menuconfig KVM
select KVM_VFIO
select HAVE_KVM_EVENTFD
select HAVE_KVM_IRQFD
+ select HAVE_KVM_DIRTY_RING_ACQ_REL
+ select HAVE_KVM_DIRTY_RING_WITH_BITMAP
select HAVE_KVM_MSI
select HAVE_KVM_IRQCHIP
select HAVE_KVM_IRQ_ROUTING
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 94d33e296e10..6b097605e38c 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -746,6 +746,9 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu)
if (kvm_check_request(KVM_REQ_SUSPEND, vcpu))
return kvm_vcpu_suspend(vcpu);
+
+ if (kvm_dirty_ring_check_request(vcpu))
+ return 0;
}
return 1;
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 60ee3d9f01f8..fbeb55e45f53 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -932,6 +932,21 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
}
+/*
+ * kvm_arch_allow_write_without_running_vcpu - allow writing guest memory
+ * without the running VCPU when dirty ring is enabled.
+ *
+ * The running VCPU is required to track dirty guest pages when dirty ring
+ * is enabled. Otherwise, the backup bitmap should be used to track the
+ * dirty guest pages. When vgic/its tables are being saved, the backup
+ * bitmap is used to track the dirty guest pages due to the missed running
+ * VCPU in the period.
+ */
+bool kvm_arch_allow_write_without_running_vcpu(struct kvm *kvm)
+{
+ return kvm_vgic_save_its_tables_in_progress(kvm);
I don't think we need the extra level of abstraction here. Just return
kvm->arch.vgic.save_its_tables_in_progress and be done with it.
You can also move the helper to the vgic-its code since they are
closely related for now.
Ok. After kvm_arch_allow_write_without_running_vcpu() is moved to vgic-its.c,
do we need to replace 'struct vgic_dist::save_its_tables_in_progress' with
a file-scoped variant ('bool vgic_its_saving_tables') ?
No, this still needs to be per-VM.
Yeah, it's still per-VM state. Sorry for my dumb question :)
Thanks,
Gavin
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