Re: [PATCH v6 16/24] KVM: arm64: vgic-its: KVM_DEV_ARM_ITS_SAVE/RESTORE_TABLES

Christoffer Dall
2017-05-05T11:55:10Z

On Thu, May 04, 2017 at 01:44:36PM +0200, Eric Auger wrote:
> Introduce new attributes in KVM_DEV_ARM_VGIC_GRP_CTRL group:
> - KVM_DEV_ARM_ITS_SAVE_TABLES: saves the ITS tables into guest RAM
> - KVM_DEV_ARM_ITS_RESTORE_TABLES: restores them into VGIC internal
> structures.
>
> We hold the vcpus lock during the save and restore to make
> sure no vcpu is running.
>
> At this stage the functionality is not yet implemented. Only
> the skeleton is put in place.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
> ---
> v5 -> v6:
> - remove the pending table sync from the ITS table restore
>
> v4 -> v5:
> - use KVM_DEV_ARM_ITS_SAVE_TABLES and KVM_DEV_ARM_ITS_RESTORE_TABLES
> - rename *flush* into *save*
> - call its_sync_lpi_pending_table at the end of restore
> - use abi framework
>
> v3 -> v4:
> - pass kvm struct handle to vgic_its_flush/restore_pending_tables
> - take the kvm lock and vcpu locks
> - ABI revision check
> - check attr->attr is null
>
> v1 -> v2:
> - remove useless kvm parameter
> ---
> arch/arm/include/uapi/asm/kvm.h | 4 +-
> arch/arm64/include/uapi/asm/kvm.h | 4 +-
> virt/kvm/arm/vgic/vgic-its.c | 101 ++++++++++++++++++++++++++++++++++++--
> 3 files changed, 103 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
> index 4beb83b..8e6563c 100644
> --- a/arch/arm/include/uapi/asm/kvm.h
> +++ b/arch/arm/include/uapi/asm/kvm.h
> @@ -199,7 +199,9 @@ struct kvm_arch_memory_slot {
> #define KVM_DEV_ARM_VGIC_LINE_LEVEL_INTID_MASK 0x3ff
> #define VGIC_LEVEL_INFO_LINE_LEVEL 0
>
> -#define KVM_DEV_ARM_VGIC_CTRL_INIT 0
> +#define KVM_DEV_ARM_VGIC_CTRL_INIT 0
> +#define KVM_DEV_ARM_ITS_SAVE_TABLES 1
> +#define KVM_DEV_ARM_ITS_RESTORE_TABLES 2
>
> /* KVM_IRQ_LINE irq field index values */
> #define KVM_ARM_IRQ_TYPE_SHIFT 24
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index 7e8dd69..1e35115 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -219,7 +219,9 @@ struct kvm_arch_memory_slot {
> #define KVM_DEV_ARM_VGIC_LINE_LEVEL_INTID_MASK 0x3ff
> #define VGIC_LEVEL_INFO_LINE_LEVEL 0
>
> -#define KVM_DEV_ARM_VGIC_CTRL_INIT 0
> +#define KVM_DEV_ARM_VGIC_CTRL_INIT 0
> +#define KVM_DEV_ARM_ITS_SAVE_TABLES 1
> +#define KVM_DEV_ARM_ITS_RESTORE_TABLES 2
>
> /* Device Control API on vcpu fd */
> #define KVM_ARM_VCPU_PMU_V3_CTRL 0
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 3ad615a..5b251dc 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1669,12 +1669,68 @@ int vgic_its_attr_regs_access(struct kvm_device *dev,
> }
>
> /**
> + * vgic_its_save_device_tables - Save the device table and all ITT
> + * into guest RAM
> + */
> +static int vgic_its_save_device_tables(struct vgic_its *its)
> +{
> + return -ENXIO;
> +}
> +
> +/**
> + * vgic_its_restore_device_tables - Restore the device table and all ITT
> + * from guest RAM to internal data structs
> + */
> +static int vgic_its_restore_device_tables(struct vgic_its *its)
> +{
> + return -ENXIO;
> +}
> +
> +/**
> + * vgic_its_save_collection_table - Save the collection table into
> + * guest RAM
> + */
> +static int vgic_its_save_collection_table(struct vgic_its *its)
> +{
> + return -ENXIO;
> +}
> +
> +/**
> + * vgic_its_restore_collection_table - reads the collection table
> + * in guest memory and restores the ITS internal state. Requires the
> + * BASER registers to be restored before.
> + */
> +static int vgic_its_restore_collection_table(struct vgic_its *its)
> +{
> + return -ENXIO;
> +}
> +
> +/**
> * vgic_its_save_tables_v0 - Save the ITS tables into guest ARM
> * according to v0 ABI
> */
> static int vgic_its_save_tables_v0(struct vgic_its *its)
> {
> - return -ENXIO;
> + struct kvm *kvm = its->dev->kvm;
> + int ret;
> +
> + mutex_lock(&kvm->lock);
> +
> + if (!lock_all_vcpus(kvm)) {
> + mutex_unlock(&kvm->lock);
> + return -EBUSY;
> + }
> +
> + ret = vgic_its_save_device_tables(its);
> + if (ret)
> + goto out;
> +
> + ret = vgic_its_save_collection_table(its);
> +
> +out:
> + unlock_all_vcpus(kvm);
> + mutex_unlock(&kvm->lock);
> + return ret;
> }
>
> /**
> @@ -1684,7 +1740,34 @@ static int vgic_its_save_tables_v0(struct vgic_its *its)
> */
> static int vgic_its_restore_tables_v0(struct vgic_its *its)
> {
> - return -ENXIO;
> + struct kvm *kvm = its->dev->kvm;
> + int ret;
> +
> + mutex_lock(&kvm->lock);
> +
> + if (!lock_all_vcpus(kvm)) {
> + mutex_unlock(&kvm->lock);
> + return -EBUSY;
> + }
> +
> + ret = vgic_its_restore_collection_table(its);
> + if (ret)
> + goto out;
> +
> + ret = vgic_its_restore_device_tables(its);
> +
> +out:
> + unlock_all_vcpus(kvm);
> + mutex_unlock(&kvm->lock);
> +
> + if (ret)
> + return ret;
> +
> + /*
> + * On restore path, MSI injections can happen before the
> + * first VCPU run so let's complete the GIC init here.
> + */
> + return kvm_vgic_map_resources(its->dev->kvm);

So not sure where we left this one in our other discussion. I feel like
this is a bit out of place currently, and registering the iodevs should
rather be done when setting the base addresses used by that, but I think
we can fix that later, or are we implying ordering towards userspace
here?

Marc, any thoughts?

Thanks,
-Christoffer