Re: [PATCH 3/5] vfio/iommu_type1: Prefer to reuse domains vs match enforced cache coherency
From: Jason Gunthorpe <jgg@nvidia.com>
Date: 2022-06-08 11:17:35
Also in:
kvm, linux-arm-msm, linux-iommu, linux-mediatek, linux-rockchip, linux-s390, linux-samsung-soc, linux-sunxi, linux-tegra, lkml
On Wed, Jun 08, 2022 at 08:28:03AM +0000, Tian, Kevin wrote:
quoted
From: Nicolin Chen Sent: Monday, June 6, 2022 2:19 PM From: Jason Gunthorpe <jgg@nvidia.com> The KVM mechanism for controlling wbinvd is only triggered during kvm_vfio_group_add(), meaning it is a one-shot test done once the devices are setup.It's not one-shot. kvm_vfio_update_coherency() is called in both group_add() and group_del(). Then the coherency property is checked dynamically in wbinvd emulation:
From the perspective of managing the domains that is still one-shot. It doesn't get updated when individual devices are added/removed to domains.
given that I'm fine with the change in this patch. Even more probably we really want an explicit one-shot model so KVM can lock down the property once it starts to consume it then further adding a new group which would change the coherency is explicitly rejected and removing an existing group leaves it intact.
Why? Once wbinvd is enabled it is compatible with all domain configurations, so just leave it on and ignore everything at that point. Jason _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel