mirror of https://gitee.com/openkylin/linux.git
5b88cda665
This fixes some inaccuracies in the state machine for the virtualized ICP when implementing the H_IPI hcall (Set_MFFR and related states): 1. The old code wipes out any pending interrupts when the new MFRR is more favored than the CPPR but less favored than a pending interrupt (by always modifying xisr and the pending_pri). This can cause us to lose a pending external interrupt. The correct code here is to only modify the pending_pri and xisr in the ICP if the MFRR is equal to or more favored than the current pending pri (since in this case, it is guaranteed that that there cannot be a pending external interrupt). The code changes are required in both kvmppc_rm_h_ipi and kvmppc_h_ipi. 2. Again, in both kvmppc_rm_h_ipi and kvmppc_h_ipi, there is a check for whether MFRR is being made less favored AND further if new MFFR is also less favored than the current CPPR, we check for any resends pending in the ICP. These checks look like they are designed to cover the case where if the MFRR is being made less favored, we opportunistically trigger a resend of any interrupts that had been previously rejected. Although, this is not a state described by PAPR, this is an action we actually need to do especially if the CPPR is already at 0xFF. Because in this case, the resend bit will stay on until another ICP state change which may be a long time coming and the interrupt stays pending until then. The current code which checks for MFRR < CPPR is broken when CPPR is 0xFF since it will not get triggered in that case. Ideally, we would want to do a resend only if prio(pending_interrupt) < mfrr && prio(pending_interrupt) < cppr where pending interrupt is the one that was rejected. But we don't have the priority of the pending interrupt state saved, so we simply trigger a resend whenever the MFRR is made less favored. 3. In kvmppc_rm_h_ipi, where we save state to pass resends to the virtual mode, we also need to save the ICP whose need_resend we reset since this does not need to be my ICP (vcpu->arch.icp) as is incorrectly assumed by the current code. A new field rm_resend_icp is added to the kvmppc_icp structure for this purpose. Signed-off-by: Suresh Warrier <warrier@linux.vnet.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de> |
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