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authorPaul Mackerras <paulus@samba.org>2013-04-18 21:51:04 +0200
committerAlexander Graf <agraf@suse.de>2013-04-26 20:27:13 +0200
commitc35635efdc0312e013ebda1c8f3b5dd038c0d0e7 (patch)
treeb4a0f054975b1d7530a9d7de85f8ac1b9fe8c60c /virt
parentKVM: PPC: Book3S HV: Make HPT reading code notice R/C bit changes (diff)
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KVM: PPC: Book3S HV: Report VPA and DTL modifications in dirty map
At present, the KVM_GET_DIRTY_LOG ioctl doesn't report modifications done by the host to the virtual processor areas (VPAs) and dispatch trace logs (DTLs) registered by the guest. This is because those modifications are done either in real mode or in the host kernel context, and in neither case does the access go through the guest's HPT, and thus no change (C) bit gets set in the guest's HPT. However, the changes done by the host do need to be tracked so that the modified pages get transferred when doing live migration. In order to track these modifications, this adds a dirty flag to the struct representing the VPA/DTL areas, and arranges to set the flag when the VPA/DTL gets modified by the host. Then, when we are collecting the dirty log, we also check the dirty flags for the VPA and DTL for each vcpu and set the relevant bit in the dirty log if necessary. Doing this also means we now need to keep track of the guest physical address of the VPA/DTL areas. So as not to lose track of modifications to a VPA/DTL area when it gets unregistered, or when a new area gets registered in its place, we need to transfer the dirty state to the rmap chain. This adds code to kvmppc_unpin_guest_page() to do that if the area was dirty. To simplify that code, we now require that all VPA, DTL and SLB shadow buffer areas fit within a single host page. Guests already comply with this requirement because pHyp requires that these areas not cross a 4k boundary. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
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