Re: [PATCH 13/19] KVM: PPC: Book3S HV: add a SYNC control for the XIVE native migration

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Jan 07, 2019 at 07:43:25PM +0100, Cédric Le Goater wrote:
> When migration of a VM is initiated, a first copy of the RAM is
> transferred to the destination before the VM is stopped. At that time,
> QEMU needs to perform a XIVE quiesce sequence to stop the flow of
> event notifications and stabilize the EQs. The sources are masked and
> the XIVE IC is synced with the KVM ioctl KVM_DEV_XIVE_GRP_SYNC.
>

Don't you also need to make sure the guests queue pages are marked
dirty here, in case they were already migrated?

> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  arch/powerpc/include/uapi/asm/kvm.h   |  1 +
>  arch/powerpc/kvm/book3s_xive_native.c | 32 +++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
> index 6fc9660c5aec..f3b859223b80 100644
> --- a/arch/powerpc/include/uapi/asm/kvm.h
> +++ b/arch/powerpc/include/uapi/asm/kvm.h
> @@ -681,6 +681,7 @@ struct kvm_ppc_cpu_char {
>  #define   KVM_DEV_XIVE_GET_TIMA_FD	2
>  #define   KVM_DEV_XIVE_VC_BASE		3
>  #define KVM_DEV_XIVE_GRP_SOURCES	2	/* 64-bit source attributes */
> +#define KVM_DEV_XIVE_GRP_SYNC		3	/* 64-bit source attributes */
>  
>  /* Layout of 64-bit XIVE source attribute values */
>  #define KVM_XIVE_LEVEL_SENSITIVE	(1ULL << 0)
> diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
> index 4ca75aade069..a8052867afc1 100644
> --- a/arch/powerpc/kvm/book3s_xive_native.c
> +++ b/arch/powerpc/kvm/book3s_xive_native.c
> @@ -459,6 +459,35 @@ static int kvmppc_xive_native_set_source(struct kvmppc_xive *xive, long irq,
>  	return 0;
>  }
>  
> +static int kvmppc_xive_native_sync(struct kvmppc_xive *xive, long irq, u64 addr)
> +{
> +	struct kvmppc_xive_src_block *sb;
> +	struct kvmppc_xive_irq_state *state;
> +	struct xive_irq_data *xd;
> +	u32 hw_num;
> +	u16 src;
> +
> +	pr_devel("%s irq=0x%lx\n", __func__, irq);
> +
> +	sb = kvmppc_xive_find_source(xive, irq, &src);
> +	if (!sb)
> +		return -ENOENT;
> +
> +	state = &sb->irq_state[src];
> +
> +	if (!state->valid)
> +		return -ENOENT;
> +
> +	arch_spin_lock(&sb->lock);
> +
> +	kvmppc_xive_select_irq(state, &hw_num, &xd);
> +	xive_native_sync_source(hw_num);
> +	xive_native_sync_queue(hw_num);
> +
> +	arch_spin_unlock(&sb->lock);
> +	return 0;
> +}
> +
>  static int kvmppc_xive_native_set_attr(struct kvm_device *dev,
>  				       struct kvm_device_attr *attr)
>  {
> @@ -474,6 +503,8 @@ static int kvmppc_xive_native_set_attr(struct kvm_device *dev,
>  	case KVM_DEV_XIVE_GRP_SOURCES:
>  		return kvmppc_xive_native_set_source(xive, attr->attr,
>  						     attr->addr);
> +	case KVM_DEV_XIVE_GRP_SYNC:
> +		return kvmppc_xive_native_sync(xive, attr->attr, attr->addr);
>  	}
>  	return -ENXIO;
>  }
> @@ -511,6 +542,7 @@ static int kvmppc_xive_native_has_attr(struct kvm_device *dev,
>  		}
>  		break;
>  	case KVM_DEV_XIVE_GRP_SOURCES:
> +	case KVM_DEV_XIVE_GRP_SYNC:
>  		if (attr->attr >= KVMPPC_XIVE_FIRST_IRQ &&
>  		    attr->attr < KVMPPC_XIVE_NR_IRQS)
>  			return 0;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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