Some Qualcomm SoCs, such as Shikra, run the modem in a separate security domain with restricted access to system memory. BAM-DMUX DMA mappings and BAM descriptor FIFOs must therefore be constrained to a designated memory region that can be shared with the modem. Accesses outside that region can trigger an XPU violation. When qcom,vmid is present, require a restricted DMA pool and assign the entire pool to both the local and remote execution environments before requesting the DMA channels. This ensures that BAM-DMUX mappings are within the assigned region. When the BAM DMA controller references the same pool, its descriptor FIFOs are covered by the assignment as well. Track the assigned execution environments explicitly and reclaim the pool for the local environment after DMA channels and mappings are released during remove or probe error cleanup. Skip the reclaim and leave the pool assigned if the remote side still holds its power vote, since it may still access the pool. Fail probing when restricted DMA pool support is unavailable, when the VMID property is malformed, when memory-region is missing, or when the restricted DMA pool is not attached to the device. Co-developed-by: Deepak Kumar Singh Signed-off-by: Deepak Kumar Singh Signed-off-by: Vishnu Santhosh --- drivers/net/wwan/Kconfig | 1 + drivers/net/wwan/qcom_bam_dmux.c | 108 ++++++++++++++++++++++++++++++++++++++- 2 files changed, 107 insertions(+), 2 deletions(-) diff --git a/drivers/net/wwan/Kconfig b/drivers/net/wwan/Kconfig index 958dbc7347fa84ee869439bf8b503037faab8bef..1b133c56231615269698140187ca3141dfe48dbf 100644 --- a/drivers/net/wwan/Kconfig +++ b/drivers/net/wwan/Kconfig @@ -65,6 +65,7 @@ config MHI_WWAN_MBIM config QCOM_BAM_DMUX tristate "Qualcomm BAM-DMUX WWAN network driver" depends on (DMA_ENGINE && PM && QCOM_SMEM_STATE) || COMPILE_TEST + select QCOM_SCM help The BAM Data Multiplexer provides access to the network data channels of modems integrated into many older Qualcomm SoCs, e.g. Qualcomm diff --git a/drivers/net/wwan/qcom_bam_dmux.c b/drivers/net/wwan/qcom_bam_dmux.c index cc6ace8d64371eb8d00c638a39b234ee540b83c9..0e7ad62f8b4e059264e89837f296ee13c0c31c9b 100644 --- a/drivers/net/wwan/qcom_bam_dmux.c +++ b/drivers/net/wwan/qcom_bam_dmux.c @@ -9,14 +9,17 @@ #include #include #include +#include #include #include #include #include +#include #include #include #include #include +#include #include #include #include @@ -75,6 +78,9 @@ struct bam_dmux { struct completion pc_ack_completion; struct dma_chan *rx, *tx; + phys_addr_t dma_pool_base; + size_t dma_pool_size; + u64 dma_pool_perms; struct bam_dmux_skb_dma rx_skbs[BAM_DMUX_NUM_SKB]; struct bam_dmux_skb_dma tx_skbs[BAM_DMUX_NUM_SKB]; spinlock_t tx_lock; /* Protect tx_skbs, tx_next_skb */ @@ -762,6 +768,90 @@ static int __maybe_unused bam_dmux_runtime_resume(struct device *dev) return 0; } +static int bam_dmux_assign_dma_pool(struct bam_dmux *dmux) +{ + struct device *dev = dmux->dev; + struct device_node *rmem_np; + struct reserved_mem *rmem; + struct qcom_scm_vmperm dst[2]; + u64 src = BIT_ULL(QCOM_SCM_VMID_HLOS); + u32 vmid; + int ret; + + if (!of_property_present(dev->of_node, "qcom,vmid")) + return 0; + + ret = of_property_read_u32(dev->of_node, "qcom,vmid", &vmid); + if (ret) + return dev_err_probe(dev, ret, "Failed to read qcom,vmid\n"); + if (vmid == QCOM_SCM_VMID_HLOS || vmid >= BITS_PER_TYPE(u64)) + return dev_err_probe(dev, -EINVAL, "Invalid qcom,vmid %u\n", vmid); + + if (!IS_ENABLED(CONFIG_DMA_RESTRICTED_POOL)) + return dev_err_probe(dev, -EOPNOTSUPP, + "qcom,vmid requires DMA_RESTRICTED_POOL\n"); + + rmem_np = of_parse_phandle(dev->of_node, "memory-region", 0); + if (!rmem_np) + return dev_err_probe(dev, -EINVAL, + "qcom,vmid requires memory-region\n"); + + rmem = of_reserved_mem_lookup(rmem_np); + of_node_put(rmem_np); + if (!rmem) + return dev_err_probe(dev, -EINVAL, + "Failed to look up restricted DMA pool\n"); + + if (!is_swiotlb_for_alloc(dev)) + return dev_err_probe(dev, -EINVAL, + "Restricted DMA pool not attached\n"); + + if (!qcom_scm_is_available()) + return -EPROBE_DEFER; + + dst[0].vmid = QCOM_SCM_VMID_HLOS; + dst[0].perm = QCOM_SCM_PERM_RW; + dst[1].vmid = vmid; + dst[1].perm = QCOM_SCM_PERM_RW; + + ret = qcom_scm_assign_mem(rmem->base, rmem->size, &src, dst, + ARRAY_SIZE(dst)); + if (ret) + return dev_err_probe(dev, ret, + "SCM assign restricted DMA pool failed\n"); + + dmux->dma_pool_base = rmem->base; + dmux->dma_pool_size = rmem->size; + /* Track the destination VMIDs explicitly for the reclaim operation. */ + dmux->dma_pool_perms = BIT_ULL(QCOM_SCM_VMID_HLOS) | BIT_ULL(vmid); + + return 0; +} + +static void bam_dmux_reclaim_dma_pool(struct bam_dmux *dmux) +{ + struct qcom_scm_vmperm hlos = { + .vmid = QCOM_SCM_VMID_HLOS, + .perm = QCOM_SCM_PERM_RW, + }; + u64 src = dmux->dma_pool_perms; + int ret; + + if (!dmux->dma_pool_perms) + return; + + ret = qcom_scm_assign_mem(dmux->dma_pool_base, dmux->dma_pool_size, &src, + &hlos, 1); + if (ret) { + dev_err(dmux->dev, "SCM reclaim restricted DMA pool failed: %d\n", ret); + return; + } + + dmux->dma_pool_perms = 0; +} + +static void bam_dmux_remove(struct platform_device *pdev); + static int bam_dmux_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; @@ -796,6 +886,10 @@ static int bam_dmux_probe(struct platform_device *pdev) "Failed to get pc-ack state\n"); dmux->pc_ack_mask = BIT(bit); + ret = bam_dmux_assign_dma_pool(dmux); + if (ret) + return ret; + init_waitqueue_head(&dmux->pc_wait); init_completion(&dmux->pc_ack_completion); complete_all(&dmux->pc_ack_completion); @@ -829,8 +923,11 @@ static int bam_dmux_probe(struct platform_device *pdev) ret = irq_get_irqchip_state(dmux->pc_irq, IRQCHIP_STATE_LINE_LEVEL, &dmux->pc_state); - if (ret) - goto err_disable_pm; + if (ret) { + /* The PC IRQ may already have powered up the RX path */ + bam_dmux_remove(pdev); + return ret; + } /* Check if remote finished initialization before us */ if (dmux->pc_state) { @@ -845,6 +942,7 @@ static int bam_dmux_probe(struct platform_device *pdev) err_disable_pm: pm_runtime_disable(dev); pm_runtime_dont_use_autosuspend(dev); + bam_dmux_reclaim_dma_pool(dmux); return ret; } @@ -879,6 +977,12 @@ static void bam_dmux_remove(struct platform_device *pdev) disable_irq(dmux->pc_irq); bam_dmux_power_off(dmux); bam_dmux_free_skbs(dmux->tx_skbs, DMA_TO_DEVICE); + + /* The remote side may still access the pool if it holds its power vote */ + if (!dmux->pc_state) + bam_dmux_reclaim_dma_pool(dmux); + else if (dmux->dma_pool_perms) + dev_warn(dev, "Leaving restricted DMA pool assigned to remote\n"); } static const struct dev_pm_ops bam_dmux_pm_ops = { -- 2.34.1