Re: [PATCH v6 24/25] iommu/tegra241-cmdqv: Add user-space use support
From: Nicolin Chen <hidden>
Date: 2025-06-26 18:51:32
Also in:
linux-doc, linux-iommu, linux-kselftest, linux-patches, linux-tegra, lkml
On Sat, Jun 14, 2025 at 12:14:49AM -0700, Nicolin Chen wrote: I made some small changes:
/** * struct tegra241_vintf - Virtual Interface + * @vsmmu: Embedded arm_vsmmu structure * @idx: Global index in the CMDQV * @enabled: Enable status * @hyp_own: Owned by hypervisor (in-kernel) * @cmdqv: Parent CMDQV pointer * @lvcmdqs: List of logical VCMDQ pointers
Added: + * @lvcmdq_mutex: Lock to serialize user-allocated lvcmdq for the following change:
quoted hunk ↗ jump to hunk
@@ -154,19 +172,41 @@ struct tegra241_vintf { struct tegra241_cmdqv *cmdqv; struct tegra241_vcmdq **lvcmdqs; + struct mutex lvcmdq_mutex; /* user space race */
[...]
+static void
+tegra241_vintf_destroy_lvcmdq_user(struct iommufd_hw_queue *hw_queue)
+{
+ struct tegra241_vcmdq *vcmdq = hw_queue_to_vcmdq(hw_queue);
+
+ tegra241_vcmdq_hw_deinit(vcmdq);
+ tegra241_vcmdq_unmap_lvcmdq(vcmdq);
+ tegra241_vintf_free_lvcmdq(vcmdq->vintf, vcmdq->lidx);
+ if (vcmdq->prev)
+ iommufd_hw_queue_undepend(vcmdq, vcmdq->prev, core);Added mutex to pair with tegra241_vintf_alloc_lvcmdq_user(): mutex_lock(&vcmdq->vintf->lvcmdq_mutex); ... mutex_unlock(&vcmdq->vintf->lvcmdq_mutex);
+ /* + * Initialize the user-owned VINTF without a LVCMDQ, because it has to + * wait for the allocation of a user-owned LVCMDQ, for security reason. + * It is different than the kernel-owned VINTF0, which had pre-assigned + * and pre-allocated global VCMDQs that would be mapped to the LVCMDQs + * by the tegra241_vintf_hw_init() call. + */ + ret = tegra241_vintf_hw_init(vintf, false);
Revised a bit: + /* + * Initialize the user-owned VINTF without a LVCMDQ, as it cannot pre- + * allocate a LVCMDQ until user space wants one, for security reasons. [...] Thanks Nicolin