Re: [PATCH 4.19 042/190] KVM: x86: hyperv: keep track of mismatched VP indexes

On Fri 2019-09-13 14:04:57, Greg Kroah-Hartman wrote:

[ Upstream commit 87ee613d076351950b74383215437f841ebbeb75 ]

In most common cases VP index of a vcpu matches its vcpu index. Userspace is, however, free to set any mapping it wishes and we need to account for that when we need to find a vCPU with a particular VP index. To keep search algorithms optimal in both cases introduce 'num_mismatched_vp_indexes' counter showing how many vCPUs with mismatching VP index we have. In case the counter is zero we can assume vp_index == vcpu_idx.

I don't see why this is stable material.

u64 hv_reenlightenment_control; u64 hv_tsc_emulation_control; u64 hv_tsc_emulation_status;

• /* How many vCPUs have VP index != vCPU index */
• atomic_t num_mismatched_vp_indexes;

};

It adds a write-only variable ...

Best regards, Pavel