Re: [PATCH v14 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing

From: Qian Cai
Date: Wed Jun 23 2021 - 12:39:41 EST



On 6/18/2021 11:40 PM, Claire Chang wrote:
> Propagate the swiotlb_force into io_tlb_default_mem->force_bounce and
> use it to determine whether to bounce the data or not. This will be
> useful later to allow for different pools.
>
> Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Tested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Tested-by: Will Deacon <will@xxxxxxxxxx>
> Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

Reverting the rest of the series up to this patch fixed a boot crash with NVMe on today's linux-next.

[ 22.286574][ T7] Unable to handle kernel paging request at virtual address dfff80000000000e
[ 22.295225][ T7] Mem abort info:
[ 22.298743][ T7] ESR = 0x96000004
[ 22.302496][ T7] EC = 0x25: DABT (current EL), IL = 32 bits
[ 22.308525][ T7] SET = 0, FnV = 0
[ 22.312274][ T7] EA = 0, S1PTW = 0
[ 22.316131][ T7] FSC = 0x04: level 0 translation fault
[ 22.321704][ T7] Data abort info:
[ 22.325278][ T7] ISV = 0, ISS = 0x00000004
[ 22.329840][ T7] CM = 0, WnR = 0
[ 22.333503][ T7] [dfff80000000000e] address between user and kernel address ranges
[ 22.338543][ T256] igb 0006:01:00.0: Intel(R) Gigabit Ethernet Network Connection
[ 22.341400][ T7] Internal error: Oops: 96000004 [#1] SMP
[ 22.348915][ T256] igb 0006:01:00.0: eth0: (PCIe:2.5Gb/s:Width x1) 4c:38:d5:09:c8:83
[ 22.354458][ T7] Modules linked in: igb(+) i2c_algo_bit nvme mlx5_core(+) i2c_core nvme_core firmware_class
[ 22.362512][ T256] igb 0006:01:00.0: eth0: PBA No: G69016-004
[ 22.372287][ T7] CPU: 13 PID: 7 Comm: kworker/u64:0 Not tainted 5.13.0-rc7-next-20210623+ #47
[ 22.372293][ T7] Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.6 06/28/2020
[ 22.372298][ T7] Workqueue: nvme-reset-wq nvme_reset_work [nvme]
[ 22.378145][ T256] igb 0006:01:00.0: Using MSI-X interrupts. 4 rx queue(s), 4 tx queue(s)
[ 22.386901][ T7]
[ 22.386905][ T7] pstate: 10000005 (nzcV daif -PAN -UAO -TCO BTYPE=--)
[ 22.386910][ T7] pc : dma_direct_map_sg+0x304/0x8f0

is_swiotlb_force_bounce at /usr/src/linux-next/./include/linux/swiotlb.h:119
(inlined by) dma_direct_map_page at /usr/src/linux-next/kernel/dma/direct.h:90
(inlined by) dma_direct_map_sg at /usr/src/linux-next/kernel/dma/direct.c:428

[ 22.386919][ T7] lr : dma_map_sg_attrs+0x6c/0x118
[ 22.386924][ T7] sp : ffff80001dc8eac0
[ 22.386926][ T7] x29: ffff80001dc8eac0 x28: ffff0000199e70b0 x27: 0000000000000000
[ 22.386935][ T7] x26: ffff000847ee7000 x25: ffff80001158e570 x24: 0000000000000002
[ 22.386943][ T7] x23: dfff800000000000 x22: 0000000000000100 x21: ffff0000199e7460
[ 22.386951][ T7] x20: ffff0000199e7488 x19: 0000000000000001 x18: ffff000010062670
[ 22.386955][ T253] Unable to handle kernel paging request at virtual address dfff80000000000e
[ 22.386958][ T7] x17: ffff8000109f6a90 x16: ffff8000109e1b4c x15: ffff800009303420
[ 22.386965][ T253] Mem abort info:
[ 22.386967][ T7] x14: 0000000000000001 x13: ffff80001158e000
[ 22.386970][ T253] ESR = 0x96000004
[ 22.386972][ T7] x12: 1fffe00108fdce01
[ 22.386975][ T253] EC = 0x25: DABT (current EL), IL = 32 bits
[ 22.386976][ T7] x11: 1fffe00108fdce03 x10: ffff000847ee700c x9 : 0000000000000004
[ 22.386981][ T253] SET = 0, FnV = 0
[ 22.386983][ T7]
[ 22.386985][ T7] x8 : ffff700003b91d72
[ 22.386986][ T253] EA = 0, S1PTW = 0
[ 22.386987][ T7] x7 : 0000000000000000 x6 : 000000000000000e
[ 22.386990][ T253] FSC = 0x04: level 0 translation fault
[ 22.386992][ T7]
[ 22.386994][ T7] x5 : dfff800000000000
[ 22.386995][ T253] Data abort info:
[ 22.386997][ T7] x4 : 00000008c7ede000
[ 22.386999][ T253] ISV = 0, ISS = 0x00000004
[ 22.386999][ T7] x3 : 00000008c7ede000
[ 22.387003][ T7] x2 : 0000000000001000
[ 22.387003][ T253] CM = 0, WnR = 0
[ 22.387006][ T7] x1 : 0000000000000000 x0 : 0000000000000071
[ 22.387008][ T253] [dfff80000000000e] address between user and kernel address ranges
[ 22.387011][ T7]
[ 22.387013][ T7] Call trace:
[ 22.387016][ T7] dma_direct_map_sg+0x304/0x8f0
[ 22.387022][ T7] dma_map_sg_attrs+0x6c/0x118
[ 22.387026][ T7] nvme_map_data+0x2ec/0x21d8 [nvme]
[ 22.387040][ T7] nvme_queue_rq+0x274/0x3f0 [nvme]
[ 22.387052][ T7] blk_mq_dispatch_rq_list+0x2ec/0x18a0
[ 22.387060][ T7] __blk_mq_sched_dispatch_requests+0x2a0/0x3e8
[ 22.387065][ T7] blk_mq_sched_dispatch_requests+0xa4/0x100
[ 22.387070][ T7] __blk_mq_run_hw_queue+0x148/0x1d8
[ 22.387075][ T7] __blk_mq_delay_run_hw_queue+0x3f8/0x730
[ 22.414539][ T269] igb 0006:01:00.0 enP6p1s0: renamed from eth0
[ 22.418957][ T7] blk_mq_run_hw_queue+0x148/0x248
[ 22.418969][ T7] blk_mq_sched_insert_request+0x2a4/0x330
[ 22.418975][ T7] blk_execute_rq_nowait+0xc8/0x118
[ 22.418981][ T7] blk_execute_rq+0xd4/0x188
[ 22.453203][ T255] udevadm (255) used greatest stack depth: 57408 bytes left
[ 22.456504][ T7] __nvme_submit_sync_cmd+0x4e0/0x730 [nvme_core]
[ 22.673245][ T7] nvme_identify_ctrl.isra.0+0x124/0x1e0 [nvme_core]
[ 22.679784][ T7] nvme_init_identify+0x90/0x1868 [nvme_core]
[ 22.685713][ T7] nvme_init_ctrl_finish+0x1a8/0xb88 [nvme_core]
[ 22.691903][ T7] nvme_reset_work+0xe5c/0x2aa4 [nvme]
[ 22.697219][ T7] process_one_work+0x7e4/0x19a0
[ 22.702005][ T7] worker_thread+0x334/0xae0
[ 22.706442][ T7] kthread+0x3bc/0x470
[ 22.710359][ T7] ret_from_fork+0x10/0x18
[ 22.714627][ T7] Code: f941ef81 9101c420 1200080e d343fc06 (38f768c6)
[ 22.721407][ T7] ---[ end trace 1f3c4181ae408676 ]---
[ 22.726712][ T7] Kernel panic - not syncing: Oops: Fatal exception
[ 22.733169][ T7] SMP: stopping secondary CPUs
[ 23.765164][ T7] SMP: failed to stop secondary CPUs 13,15
[ 23.770818][ T7] Kernel Offset: disabled
[ 23.774991][ T7] CPU features: 0x00000251,20000846
[ 23.780034][ T7] Memory Limit: none
[ 23.783794][ T7] ---[ end Kernel panic - not syncing: Oops: Fatal exception ]---

> ---
> drivers/xen/swiotlb-xen.c | 2 +-
> include/linux/swiotlb.h | 11 +++++++++++
> kernel/dma/direct.c | 2 +-
> kernel/dma/direct.h | 2 +-
> kernel/dma/swiotlb.c | 4 ++++
> 5 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 0c6ed09f8513..4730a146fa35 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -369,7 +369,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
> if (dma_capable(dev, dev_addr, size, true) &&
> !range_straddles_page_boundary(phys, size) &&
> !xen_arch_need_swiotlb(dev, phys, dev_addr) &&
> - swiotlb_force != SWIOTLB_FORCE)
> + !is_swiotlb_force_bounce(dev))
> goto done;
>
> /*
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index dd1c30a83058..8d8855c77d9a 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -84,6 +84,7 @@ extern enum swiotlb_force swiotlb_force;
> * unmap calls.
> * @debugfs: The dentry to debugfs.
> * @late_alloc: %true if allocated using the page allocator
> + * @force_bounce: %true if swiotlb bouncing is forced
> */
> struct io_tlb_mem {
> phys_addr_t start;
> @@ -94,6 +95,7 @@ struct io_tlb_mem {
> spinlock_t lock;
> struct dentry *debugfs;
> bool late_alloc;
> + bool force_bounce;
> struct io_tlb_slot {
> phys_addr_t orig_addr;
> size_t alloc_size;
> @@ -109,6 +111,11 @@ static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
> return mem && paddr >= mem->start && paddr < mem->end;
> }
>
> +static inline bool is_swiotlb_force_bounce(struct device *dev)
> +{
> + return dev->dma_io_tlb_mem->force_bounce;
> +}
> +
> void __init swiotlb_exit(void);
> unsigned int swiotlb_max_segment(void);
> size_t swiotlb_max_mapping_size(struct device *dev);
> @@ -120,6 +127,10 @@ static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
> {
> return false;
> }
> +static inline bool is_swiotlb_force_bounce(struct device *dev)
> +{
> + return false;
> +}
> static inline void swiotlb_exit(void)
> {
> }
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 7a88c34d0867..a92465b4eb12 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -496,7 +496,7 @@ size_t dma_direct_max_mapping_size(struct device *dev)
> {
> /* If SWIOTLB is active, use its maximum mapping size */
> if (is_swiotlb_active(dev) &&
> - (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE))
> + (dma_addressing_limited(dev) || is_swiotlb_force_bounce(dev)))
> return swiotlb_max_mapping_size(dev);
> return SIZE_MAX;
> }
> diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
> index 13e9e7158d94..4632b0f4f72e 100644
> --- a/kernel/dma/direct.h
> +++ b/kernel/dma/direct.h
> @@ -87,7 +87,7 @@ static inline dma_addr_t dma_direct_map_page(struct device *dev,
> phys_addr_t phys = page_to_phys(page) + offset;
> dma_addr_t dma_addr = phys_to_dma(dev, phys);
>
> - if (unlikely(swiotlb_force == SWIOTLB_FORCE))
> + if (is_swiotlb_force_bounce(dev))
> return swiotlb_map(dev, phys, size, dir, attrs);
>
> if (unlikely(!dma_capable(dev, dma_addr, size, true))) {
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 8a120f42340b..0d294bbf274c 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -179,6 +179,10 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
> mem->end = mem->start + bytes;
> mem->index = 0;
> mem->late_alloc = late_alloc;
> +
> + if (swiotlb_force == SWIOTLB_FORCE)
> + mem->force_bounce = true;
> +
> spin_lock_init(&mem->lock);
> for (i = 0; i < mem->nslabs; i++) {
> mem->slots[i].list = IO_TLB_SEGSIZE - io_tlb_offset(i);
>