From: Jason Gunthorpe <jgg@ziepe.ca>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Sean Christopherson <seanjc@google.com>,
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
kvmarm@lists.linux.dev, iommu@lists.linux.dev,
linux-arm-kernel@lists.infradead.org, linuxarm@huawei.com,
kevin.tian@intel.com, alex.williamson@redhat.com, maz@kernel.org,
will@kernel.org, robin.murphy@arm.com, jean-philippe@linaro.org,
jonathan.cameron@huawei.com
Subject: Re: [RFC PATCH v2 4/7] iommufd: Associate kvm pointer to iommufd ctx
Date: Mon, 24 Jun 2024 19:35:35 -0300 [thread overview]
Message-ID: <20240624223535.GA1781035@ziepe.ca> (raw)
In-Reply-To: <ZnnORmCHrEI0KkGz@linux.dev>
On Mon, Jun 24, 2024 at 12:51:34PM -0700, Oliver Upton wrote:
> Having the SMMU participate in broadcast TLB maintenance means TLBI
> instructions on the CPU invalidate translations in the SMMU, which is
> useful for SVA usecases. However, if the host is using different VMIDs
> for the CPU and SMMU, then guest TLBIs no longer match the guest's SMMU
> context...
>
> Pinning / sharing the VMID between CPU and SMMU is a hard requirement if
> you advertise BTM support to the guest.
Yes, and the extra detail that the SMMU *must* always have a unique
VMID for the specific VM, we can't leave it in a state without one.
Meaning there is little purpose to changing the VMID at runtime as you
can't multiplex more VM's than you have IDs once the SMMU is using it
anyhow.
Jason
next prev parent reply other threads:[~2024-06-24 22:35 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-08 15:18 [RFC PATCH v2 0/7] iommu/arm-smmu-v3: Use pinned KVM VMID for stage 2 Shameer Kolothum
2024-02-08 15:18 ` [RFC PATCH v2 1/7] KVM: Add generic infrastructure to support pinned VMIDs Shameer Kolothum
2024-06-24 15:48 ` Sean Christopherson
2024-02-08 15:18 ` [RFC PATCH v2 2/7] KVM: arm64: Introduce support to pin VMIDs Shameer Kolothum
2024-06-24 19:22 ` Oliver Upton
2024-06-24 19:34 ` Shameerali Kolothum Thodi
2024-06-24 19:52 ` Oliver Upton
2024-02-08 15:18 ` [RFC PATCH v2 3/7] KVM: arm64: Add interfaces for pinned VMID support Shameer Kolothum
2024-02-08 15:18 ` [RFC PATCH v2 4/7] iommufd: Associate kvm pointer to iommufd ctx Shameer Kolothum
2024-02-08 15:42 ` Jason Gunthorpe
2024-06-24 16:53 ` Sean Christopherson
2024-06-24 17:07 ` Jason Gunthorpe
2024-06-24 17:54 ` Sean Christopherson
2024-06-24 18:01 ` Jason Gunthorpe
2024-06-24 19:12 ` Oliver Upton
2024-06-24 19:29 ` Sean Christopherson
2024-06-24 19:51 ` Oliver Upton
2024-06-24 22:35 ` Jason Gunthorpe [this message]
2024-06-25 2:21 ` Tian, Kevin
2024-06-24 19:13 ` Shameerali Kolothum Thodi
2024-06-25 1:53 ` Tian, Kevin
2024-02-08 15:18 ` [RFC PATCH v2 5/7] iommu: Pass in kvm pointer to domain_alloc_user Shameer Kolothum
2024-02-08 15:43 ` Jason Gunthorpe
2024-02-08 15:18 ` [RFC PATCH v2 6/7] iommu/arm-smmu-v3: Use KVM VMID for s2 stage Shameer Kolothum
2024-02-08 15:59 ` Jason Gunthorpe
2024-02-08 16:14 ` Shameerali Kolothum Thodi
2024-02-08 16:26 ` Jason Gunthorpe
2024-02-08 16:36 ` Shameerali Kolothum Thodi
2024-02-08 15:18 ` [RFC PATCH v2 7/7] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Shameer Kolothum
2024-02-08 15:35 ` [RFC PATCH v2 0/7] iommu/arm-smmu-v3: Use pinned KVM VMID for stage 2 Jason Gunthorpe
2024-02-08 15:49 ` Shameerali Kolothum Thodi
2024-02-08 16:07 ` Jason Gunthorpe
2024-02-09 11:58 ` Jean-Philippe Brucker
2024-02-09 12:48 ` Jason Gunthorpe
2024-02-09 13:54 ` Shameerali Kolothum Thodi
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