From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>,
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Subject: Re: [PATCH 3/5] vfio/iommu_type1: Prefer to reuse domains vs match enforced cache coherency
Date: Wed, 8 Jun 2022 08:17:24 -0300 [thread overview]
Message-ID: <20220608111724.GL1343366@nvidia.com> (raw)
In-Reply-To: <BN9PR11MB5276DC98E75B1906A76F7ADC8CA49@BN9PR11MB5276.namprd11.prod.outlook.com>
On Wed, Jun 08, 2022 at 08:28:03AM +0000, Tian, Kevin wrote:
> > 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
next prev parent reply other threads:[~2022-06-08 11:17 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-06 6:19 [PATCH 0/5] Simplify vfio_iommu_type1 attach/detach routine Nicolin Chen
2022-06-06 6:19 ` [PATCH 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group Nicolin Chen
2022-06-07 3:23 ` Baolu Lu
2022-06-07 4:03 ` Nicolin Chen
2022-06-08 7:49 ` Tian, Kevin
2022-06-08 17:38 ` Nicolin Chen
2022-06-06 6:19 ` [PATCH 2/5] iommu: Ensure device has the same iommu_ops as the domain Nicolin Chen
2022-06-06 14:33 ` Robin Murphy
2022-06-06 16:51 ` Nicolin Chen
2022-06-06 17:50 ` Robin Murphy
2022-06-06 18:28 ` Nicolin Chen
2022-06-06 18:52 ` Jason Gunthorpe
2022-06-06 6:19 ` [PATCH 3/5] vfio/iommu_type1: Prefer to reuse domains vs match enforced cache coherency Nicolin Chen
2022-06-08 8:28 ` Tian, Kevin
2022-06-08 11:17 ` Jason Gunthorpe [this message]
2022-06-08 23:48 ` Tian, Kevin
2022-06-14 20:45 ` Nicolin Chen
2022-06-15 7:35 ` Tian, Kevin
2022-06-15 23:12 ` Nicolin Chen
2022-06-06 6:19 ` [PATCH 4/5] vfio/iommu_type1: Clean up update_dirty_scope in detach_group() Nicolin Chen
2022-06-08 8:35 ` Tian, Kevin
2022-06-08 17:46 ` Nicolin Chen
2022-06-06 6:19 ` [PATCH 5/5] vfio/iommu_type1: Simplify group attachment Nicolin Chen
2022-06-07 7:44 ` [PATCH 0/5] Simplify vfio_iommu_type1 attach/detach routine Baolu Lu
2022-06-07 11:58 ` Jason Gunthorpe
2022-06-07 12:42 ` Baolu Lu
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