From: Jason Gunthorpe <jgg@nvidia.com>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>,
"will@kernel.org" <will@kernel.org>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
"vdumpa@nvidia.com" <vdumpa@nvidia.com>,
"jonathanh@nvidia.com" <jonathanh@nvidia.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
Jerry Snitselaar <jsnitsel@redhat.com>
Subject: Re: [PATCH v5 0/6] Add Tegra241 (Grace) CMDQV Support (part 1/2)
Date: Wed, 17 Apr 2024 09:24:45 -0300 [thread overview]
Message-ID: <20240417122445.GO3637727@nvidia.com> (raw)
In-Reply-To: <f92efdb774cc4cd48a59495e7cb69c27@huawei.com>
On Wed, Apr 17, 2024 at 08:01:10AM +0000, Shameerali Kolothum Thodi wrote:
> We do have plans to revive the SMMUv3 ECMDQ series posted a while back[0]
> and looking at this series, I am just wondering whether it makes sense to have
> a similar one with ECMDQ as well? I see that the NVIDIA VCMDQ has a special bit
> to restrict the commands that can be issued from user space. If we end up assigning
> a ECMDQ to user space, is there any potential risk in doing so?
I think there is some risk/trouble, ECMDQ needs some enhancement
before it can be really safe to use from less privileged software, and
it wasn't designed to have an isolated doorbell page either.
> Not clear to me what are the major concerns here and maybe we can come up with
> something to address that in kernel.
I haven't looked deeply but my impression has been the ECMDQ is not
workable to support virtualization. At a minimum it has no way to
constrain the command flow to a VMID and to do VSID -> PSID
translation.
I suggest you talk directly to ARM on this if you are interested in
this.
Jason
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next prev parent reply other threads:[~2024-04-17 12:25 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-13 3:43 [PATCH v5 0/6] Add Tegra241 (Grace) CMDQV Support (part 1/2) Nicolin Chen
2024-04-13 3:43 ` [PATCH v5 1/6] iommu/arm-smmu-v3: Add CS_NONE quirk Nicolin Chen
2024-04-19 17:12 ` Nicolin Chen
2024-04-13 3:43 ` [PATCH v5 2/6] iommu/arm-smmu-v3: Make arm_smmu_cmdq_init reusable Nicolin Chen
2024-04-13 3:43 ` [PATCH v5 3/6] iommu/arm-smmu-v3: Make __arm_smmu_cmdq_skip_err reusable Nicolin Chen
2024-04-13 3:43 ` [PATCH v5 4/6] iommu/arm-smmu-v3: Pass in cmdq pointer to arm_smmu_cmdq_issue_cmdlist() Nicolin Chen
2024-04-13 3:43 ` [PATCH v5 5/6] iommu/arm-smmu-v3: Add in-kernel support for NVIDIA Tegra241 (Grace) CMDQV Nicolin Chen
2024-04-13 3:43 ` [PATCH v5 6/6] iommu/tegra241-cmdqv: Limit CMDs for guest owned VINTF Nicolin Chen
2024-04-17 15:12 ` Shameerali Kolothum Thodi
2024-04-17 16:04 ` Nicolin Chen
2024-04-15 17:14 ` [PATCH v5 0/6] Add Tegra241 (Grace) CMDQV Support (part 1/2) Jason Gunthorpe
2024-04-17 8:01 ` Shameerali Kolothum Thodi
2024-04-17 9:45 ` Shameerali Kolothum Thodi
2024-04-17 12:29 ` Jason Gunthorpe
2024-04-17 12:24 ` Jason Gunthorpe [this message]
2024-04-17 15:13 ` Shameerali Kolothum Thodi
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