Re: [PATCH 0/3] KVM: x86: KVM_MEM_PCI_HOLE memory

From: Vitaly Kuznetsov
Date: Thu Aug 06 2020 - 13:21:17 EST

"Michael S. Tsirkin" <mst@xxxxxxxxxx> writes:

> About the feature bit, I am not sure why it's really needed. A single
> mmio access is cheaper than two io accesses anyway, right? So it makes
> sense for a kvm guest whether host has this feature or not.
> We need to be careful and limit to a specific QEMU implementation
> to avoid tripping up bugs, but it seems more appropriate to
> check it using pci host IDs.

Right, it's just that "running on KVM" is too coarse grained, we just
need a way to somehow distinguish between "known/good" and
"unknown/buggy" configurations.