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SubjectRe: [PATCH v3] nvme-pci: Support shared tags across queues for Apple 2018 controllers
On Fri, Jul 19, 2019 at 1:31 PM Benjamin Herrenschmidt
<benh@kernel.crashing.org> wrote:
>
> From 8dcba2ef5b1466b023b88b4eca463b30de78d9eb Mon Sep 17 00:00:00 2001
> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Date: Fri, 19 Jul 2019 15:03:06 +1000
> Subject:
>
> Another issue with the Apple T2 based 2018 controllers seem to be
> that they blow up (and shut the machine down) if there's a tag
> collision between the IO queue and the Admin queue.
>
> My suspicion is that they use our tags for their internal tracking
> and don't mix them with the queue id. They also seem to not like
> when tags go beyond the IO queue depth, ie 128 tags.
>
> This adds a quirk that marks tags 0..31 of the IO queue reserved
>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>
> Thanks Damien, reserved tags work and make this a lot simpler !
>
> drivers/nvme/host/nvme.h | 5 +++++
> drivers/nvme/host/pci.c | 19 ++++++++++++++++++-
> 2 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index ced0e0a7e039..8732da6df555 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -102,6 +102,11 @@ enum nvme_quirks {
> * Use non-standard 128 bytes SQEs.
> */
> NVME_QUIRK_128_BYTES_SQES = (1 << 11),
> +
> + /*
> + * Prevent tag overlap between queues
> + */
> + NVME_QUIRK_SHARED_TAGS = (1 << 12),
> };
>
> /*
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 7088971d4c42..fc74395a028b 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2106,6 +2106,14 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
> unsigned long size;
>
> nr_io_queues = max_io_queues();
> +
> + /*
> + * If tags are shared with admin queue (Apple bug), then
> + * make sure we only use one IO queue.
> + */
> + if (dev->ctrl.quirks & NVME_QUIRK_SHARED_TAGS)
> + nr_io_queues = 1;
> +
> result = nvme_set_queue_count(&dev->ctrl, &nr_io_queues);
> if (result < 0)
> return result;
> @@ -2278,6 +2286,14 @@ static int nvme_dev_add(struct nvme_dev *dev)
> dev->tagset.flags = BLK_MQ_F_SHOULD_MERGE;
> dev->tagset.driver_data = dev;
>
> + /*
> + * Some Apple controllers requires tags to be unique
> + * across admin and IO queue, so reserve the first 32
> + * tags of the IO queue.
> + */
> + if (dev->ctrl.quirks & NVME_QUIRK_SHARED_TAGS)
> + dev->tagset.reserved_tags = NVME_AQ_DEPTH;
> +
> ret = blk_mq_alloc_tag_set(&dev->tagset);
> if (ret) {
> dev_warn(dev->ctrl.device,
> @@ -3057,7 +3073,8 @@ static const struct pci_device_id nvme_id_table[] = {
> { PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2003) },
> { PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2005),
> .driver_data = NVME_QUIRK_SINGLE_VECTOR |
> - NVME_QUIRK_128_BYTES_SQES },
> + NVME_QUIRK_128_BYTES_SQES |
> + NVME_QUIRK_SHARED_TAGS },
> { 0, }
> };
> MODULE_DEVICE_TABLE(pci, nvme_id_table);

Looks fine for me:

Reviewed-by: Ming Lei <ming.lei@redhat.com>

Thanks,
Ming Lei

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