On 2/4/19 6:18 AM, David Gibson wrote:
> On Mon, Jan 07, 2019 at 07:43:26PM +0100, Cédric Le Goater wrote:
>> When the VM is stopped in a migration sequence, the sources are masked
>> and the XIVE IC is synced to stabilize the EQs. When done, the KVM
>> ioctl KVM_DEV_XIVE_SAVE_EQ_PAGES is called to mark dirty the EQ pages.
>>
>> The migration can then transfer the remaining dirty pages to the
>> destination and start collecting the state of the devices.
>
> Is there a reason to make this a separate step from the SYNC
> operation?
Hmm, apart from letting QEMU orchestrate the migration step by step, no.
We could merge the SYNC and the SAVE_EQ_PAGES in a single KVM operation.
I think that should be fine.
However, it does not make sense to call this operation without the VM
being stopped. I wonder how this can checked from KVM. May be we can't.
C.
>
>>
>> Signed-off-by: Cédric Le Goater <clg@xxxxxxxx>
>> ---
>> arch/powerpc/include/uapi/asm/kvm.h | 1 +
>> arch/powerpc/kvm/book3s_xive_native.c | 40 +++++++++++++++++++++++++++
>> 2 files changed, 41 insertions(+)
>>
>> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
>> index f3b859223b80..1a8740629acf 100644
>> --- a/arch/powerpc/include/uapi/asm/kvm.h
>> +++ b/arch/powerpc/include/uapi/asm/kvm.h
>> @@ -680,6 +680,7 @@ struct kvm_ppc_cpu_char {
>> #define KVM_DEV_XIVE_GET_ESB_FD 1
>> #define KVM_DEV_XIVE_GET_TIMA_FD 2
>> #define KVM_DEV_XIVE_VC_BASE 3
>> +#define KVM_DEV_XIVE_SAVE_EQ_PAGES 4
>> #define KVM_DEV_XIVE_GRP_SOURCES 2 /* 64-bit source attributes */
>> #define KVM_DEV_XIVE_GRP_SYNC 3 /* 64-bit source attributes */
>>
>> diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
>> index a8052867afc1..f2de1bcf3b35 100644
>> --- a/arch/powerpc/kvm/book3s_xive_native.c
>> +++ b/arch/powerpc/kvm/book3s_xive_native.c
>> @@ -373,6 +373,43 @@ static int kvmppc_xive_native_get_tima_fd(struct kvmppc_xive *xive, u64 addr)
>> return put_user(ret, ubufp);
>> }
>>
>> +static int kvmppc_xive_native_vcpu_save_eq_pages(struct kvm_vcpu *vcpu)
>> +{
>> + struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;
>> + unsigned int prio;
>> +
>> + if (!xc)
>> + return -ENOENT;
>> +
>> + for (prio = 0; prio < KVMPPC_XIVE_Q_COUNT; prio++) {
>> + struct xive_q *q = &xc->queues[prio];
>> +
>> + if (!q->qpage)
>> + continue;
>> +
>> + /* Mark EQ page dirty for migration */
>> + mark_page_dirty(vcpu->kvm, gpa_to_gfn(q->guest_qpage));
>> + }
>> + return 0;
>> +}
>> +
>> +static int kvmppc_xive_native_save_eq_pages(struct kvmppc_xive *xive)
>> +{
>> + struct kvm *kvm = xive->kvm;
>> + struct kvm_vcpu *vcpu;
>> + unsigned int i;
>> +
>> + pr_devel("%s\n", __func__);
>> +
>> + mutex_lock(&kvm->lock);
>> + kvm_for_each_vcpu(i, vcpu, kvm) {
>> + kvmppc_xive_native_vcpu_save_eq_pages(vcpu);
>> + }
>> + mutex_unlock(&kvm->lock);
>> +
>> + return 0;
>> +}
>> +
>> static int xive_native_validate_queue_size(u32 qsize)
>> {
>> switch (qsize) {
>> @@ -498,6 +535,8 @@ static int kvmppc_xive_native_set_attr(struct kvm_device *dev,
>> switch (attr->attr) {
>> case KVM_DEV_XIVE_VC_BASE:
>> return kvmppc_xive_native_set_vc_base(xive, attr->addr);
>> + case KVM_DEV_XIVE_SAVE_EQ_PAGES:
>> + return kvmppc_xive_native_save_eq_pages(xive);
>> }
>> break;
>> case KVM_DEV_XIVE_GRP_SOURCES:
>> @@ -538,6 +577,7 @@ static int kvmppc_xive_native_has_attr(struct kvm_device *dev,
>> case KVM_DEV_XIVE_GET_ESB_FD:
>> case KVM_DEV_XIVE_GET_TIMA_FD:
>> case KVM_DEV_XIVE_VC_BASE:
>> + case KVM_DEV_XIVE_SAVE_EQ_PAGES:
>> return 0;
>> }
>> break;
>
