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.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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