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Date: Tue, 14 Dec 2021 07:01:10 +0900
From: Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To: John Garry <john.garry@...wei.com>, jinpu.wang@...ud.ionos.com,
jejb@...ux.ibm.com, martin.petersen@...cle.com
Cc: Viswas.G@...rochip.com, Ajish.Koshy@...rochip.com,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] scsi: pm8001: Fix phys_to_virt() usage on dma_addr_t
On 2021/12/13 19:10, John Garry wrote:
> The driver supports a "direct" mode of operation, where the SMP req frame
> is directly copied into the command payload (and vice-versa for the SMP
> resp).
>
> To get at the SMP req frame data in the scatterlist the driver uses
> phys_to_virt() on the DMA mapped memory dma_addr_t . This is broken,
> and subsequently crashes as follows when an IOMMU is enabled:
>
> Unable to handle kernel paging request at virtual address
> ffff0000fcebfb00
> ...
> pc : pm80xx_chip_smp_req+0x2d0/0x3d0
> lr : pm80xx_chip_smp_req+0xac/0x3d0
> pm80xx_chip_smp_req+0x2d0/0x3d0
> pm8001_task_exec.constprop.0+0x368/0x520
> pm8001_queue_command+0x1c/0x30
> smp_execute_task_sg+0xdc/0x204
> sas_discover_expander.part.0+0xac/0x6cc
> sas_discover_root_expander+0x8c/0x150
> sas_discover_domain+0x3ac/0x6a0
> process_one_work+0x1d0/0x354
> worker_thread+0x13c/0x470
> kthread+0x17c/0x190
> ret_from_fork+0x10/0x20
> Code: 371806e1 910006d6 6b16033f 54000249 (38766b05)
> ---[ end trace b91d59aaee98ea2d ]---
> note: kworker/u192:0[7] exited with preempt_count 1
>
> Instead use kmap_atomic().
>
> Signed-off-by: John Garry <john.garry@...wei.com>
> --
> Difference to v1:
> - use kmap_atomic() in both locations
> Difference to v2:
> - add whitespace around arithmetic (Damien)
>
> diff --git a/drivers/scsi/pm8001/pm80xx_hwi.c b/drivers/scsi/pm8001/pm80xx_hwi.c
> index b9f6d83ff380..2101fc5761c3 100644
> --- a/drivers/scsi/pm8001/pm80xx_hwi.c
> +++ b/drivers/scsi/pm8001/pm80xx_hwi.c
> @@ -3053,7 +3053,6 @@ mpi_smp_completion(struct pm8001_hba_info *pm8001_ha, void *piomb)
> struct smp_completion_resp *psmpPayload;
> struct task_status_struct *ts;
> struct pm8001_device *pm8001_dev;
> - char *pdma_respaddr = NULL;
>
> psmpPayload = (struct smp_completion_resp *)(piomb + 4);
> status = le32_to_cpu(psmpPayload->status);
> @@ -3080,19 +3079,23 @@ mpi_smp_completion(struct pm8001_hba_info *pm8001_ha, void *piomb)
> if (pm8001_dev)
> atomic_dec(&pm8001_dev->running_req);
> if (pm8001_ha->smp_exp_mode == SMP_DIRECT) {
> + struct scatterlist *sg_resp = &t->smp_task.smp_resp;
> + u8 *payload;
> + void *to;
> +
> pm8001_dbg(pm8001_ha, IO,
> "DIRECT RESPONSE Length:%d\n",
> param);
> - pdma_respaddr = (char *)(phys_to_virt(cpu_to_le64
> - ((u64)sg_dma_address
> - (&t->smp_task.smp_resp))));
> + to = kmap_atomic(sg_page(sg_resp));
> + payload = to + sg_resp->offset;
> for (i = 0; i < param; i++) {
> - *(pdma_respaddr+i) = psmpPayload->_r_a[i];
> + *(payload + i) = psmpPayload->_r_a[i];
> pm8001_dbg(pm8001_ha, IO,
> "SMP Byte%d DMA data 0x%x psmp 0x%x\n",
> - i, *(pdma_respaddr + i),
> + i, *(payload + i),
> psmpPayload->_r_a[i]);
> }
> + kunmap_atomic(to);
> }
> break;
> case IO_ABORTED:
> @@ -4236,14 +4239,14 @@ static int pm80xx_chip_smp_req(struct pm8001_hba_info *pm8001_ha,
> struct sas_task *task = ccb->task;
> struct domain_device *dev = task->dev;
> struct pm8001_device *pm8001_dev = dev->lldd_dev;
> - struct scatterlist *sg_req, *sg_resp;
> + struct scatterlist *sg_req, *sg_resp, *smp_req;
> u32 req_len, resp_len;
> struct smp_req smp_cmd;
> u32 opc;
> struct inbound_queue_table *circularQ;
> - char *preq_dma_addr = NULL;
> - __le64 tmp_addr;
> u32 i, length;
> + u8 *payload;
> + u8 *to;
>
> memset(&smp_cmd, 0, sizeof(smp_cmd));
> /*
> @@ -4280,8 +4283,9 @@ static int pm80xx_chip_smp_req(struct pm8001_hba_info *pm8001_ha,
> pm8001_ha->smp_exp_mode = SMP_INDIRECT;
>
>
> - tmp_addr = cpu_to_le64((u64)sg_dma_address(&task->smp_task.smp_req));
> - preq_dma_addr = (char *)phys_to_virt(tmp_addr);
> + smp_req = &task->smp_task.smp_req;
> + to = kmap_atomic(sg_page(smp_req));
> + payload = to + smp_req->offset;
>
> /* INDIRECT MODE command settings. Use DMA */
> if (pm8001_ha->smp_exp_mode == SMP_INDIRECT) {
> @@ -4289,7 +4293,7 @@ static int pm80xx_chip_smp_req(struct pm8001_hba_info *pm8001_ha,
> /* for SPCv indirect mode. Place the top 4 bytes of
> * SMP Request header here. */
> for (i = 0; i < 4; i++)
> - smp_cmd.smp_req16[i] = *(preq_dma_addr + i);
> + smp_cmd.smp_req16[i] = *(payload + i);
> /* exclude top 4 bytes for SMP req header */
> smp_cmd.long_smp_req.long_req_addr =
> cpu_to_le64((u64)sg_dma_address
> @@ -4320,20 +4324,20 @@ static int pm80xx_chip_smp_req(struct pm8001_hba_info *pm8001_ha,
> pm8001_dbg(pm8001_ha, IO, "SMP REQUEST DIRECT MODE\n");
> for (i = 0; i < length; i++)
> if (i < 16) {
> - smp_cmd.smp_req16[i] = *(preq_dma_addr+i);
> + smp_cmd.smp_req16[i] = *(payload + i);
> pm8001_dbg(pm8001_ha, IO,
> "Byte[%d]:%x (DMA data:%x)\n",
> i, smp_cmd.smp_req16[i],
> - *(preq_dma_addr));
> + *(payload));
> } else {
> - smp_cmd.smp_req[i] = *(preq_dma_addr+i);
> + smp_cmd.smp_req[i] = *(payload + i);
> pm8001_dbg(pm8001_ha, IO,
> "Byte[%d]:%x (DMA data:%x)\n",
> i, smp_cmd.smp_req[i],
> - *(preq_dma_addr));
> + *(payload));
> }
> }
> -
> + kunmap_atomic(to);
> build_smp_cmd(pm8001_dev->device_id, smp_cmd.tag,
> &smp_cmd, pm8001_ha->smp_exp_mode, length);
> rc = pm8001_mpi_build_cmd(pm8001_ha, circularQ, opc, &smp_cmd,
Looks good to me.
Reviewed-by: Damien Le Moal <damien.lemoal@...nsource.wdc.com>
--
Damien Le Moal
Western Digital Research
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