From: Bjorn Helgaas <helgaas@kernel.org>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: virtio-dev@lists.oasis-open.org, kevin.tian@intel.com,
mst@redhat.com, linux-pci@vger.kernel.org,
virtualization@lists.linux-foundation.org,
iommu@lists.linux-foundation.org, sebastien.boeuf@intel.com,
bhelgaas@google.com, jasowang@redhat.com
Subject: Re: [PATCH v3 5/6] iommu/virtio: Support topology description in config space
Date: Thu, 24 Sep 2020 10:22:03 -0500 [thread overview]
Message-ID: <20200924152203.GA2320481@bjorn-Precision-5520> (raw)
In-Reply-To: <20200821131540.2801801-6-jean-philippe@linaro.org>
On Fri, Aug 21, 2020 at 03:15:39PM +0200, Jean-Philippe Brucker wrote:
> Platforms without device-tree nor ACPI can provide a topology
> description embedded into the virtio config space. Parse it.
>
> Use PCI FIXUP to probe the config space early, because we need to
> discover the topology before any DMA configuration takes place, and the
> virtio driver may be loaded much later. Since we discover the topology
> description when probing the PCI hierarchy, the virtual IOMMU cannot
> manage other platform devices discovered earlier.
> +struct viommu_cap_config {
> + u8 bar;
> + u32 length; /* structure size */
> + u32 offset; /* structure offset within the bar */
s/the bar/the BAR/ (to match comment below).
> +static void viommu_pci_parse_topology(struct pci_dev *dev)
> +{
> + int ret;
> + u32 features;
> + void __iomem *regs, *common_regs;
> + struct viommu_cap_config cap = {0};
> + struct virtio_pci_common_cfg __iomem *common_cfg;
> +
> + /*
> + * The virtio infrastructure might not be loaded at this point. We need
> + * to access the BARs ourselves.
> + */
> + ret = viommu_pci_find_capability(dev, VIRTIO_PCI_CAP_COMMON_CFG, &cap);
> + if (!ret) {
> + pci_warn(dev, "common capability not found\n");
Is the lack of this capability really an error, i.e., is this
pci_warn() or pci_info()? The "device doesn't have topology
description" below is only pci_dbg(), which suggests that we can live
without this.
Maybe a hint about what "common capability" means?
> + return;
> + }
> +
> + if (pci_enable_device_mem(dev))
> + return;
> +
> + common_regs = pci_iomap(dev, cap.bar, 0);
> + if (!common_regs)
> + return;
> +
> + common_cfg = common_regs + cap.offset;
> +
> + /* Perform the init sequence before we can read the config */
> + ret = viommu_pci_reset(common_cfg);
I guess this is some special device-specific reset, not any kind of
standard PCI reset?
> + if (ret < 0) {
> + pci_warn(dev, "unable to reset device\n");
> + goto out_unmap_common;
> + }
> +
> + iowrite8(VIRTIO_CONFIG_S_ACKNOWLEDGE, &common_cfg->device_status);
> + iowrite8(VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER,
> + &common_cfg->device_status);
> +
> + /* Find out if the device supports topology description */
> + iowrite32(0, &common_cfg->device_feature_select);
> + features = ioread32(&common_cfg->device_feature);
> +
> + if (!(features & BIT(VIRTIO_IOMMU_F_TOPOLOGY))) {
> + pci_dbg(dev, "device doesn't have topology description");
> + goto out_reset;
> + }
> +
> + ret = viommu_pci_find_capability(dev, VIRTIO_PCI_CAP_DEVICE_CFG, &cap);
> + if (!ret) {
> + pci_warn(dev, "device config capability not found\n");
> + goto out_reset;
> + }
> +
> + regs = pci_iomap(dev, cap.bar, 0);
> + if (!regs)
> + goto out_reset;
> +
> + pci_info(dev, "parsing virtio-iommu topology\n");
> + ret = viommu_parse_topology(&dev->dev, regs + cap.offset,
> + pci_resource_len(dev, 0) - cap.offset);
> + if (ret)
> + pci_warn(dev, "failed to parse topology: %d\n", ret);
> +
> + pci_iounmap(dev, regs);
> +out_reset:
> + ret = viommu_pci_reset(common_cfg);
> + if (ret)
> + pci_warn(dev, "unable to reset device\n");
> +out_unmap_common:
> + pci_iounmap(dev, common_regs);
> +}
> +
> +/*
> + * Catch a PCI virtio-iommu implementation early to get the topology description
> + * before we start probing other endpoints.
> + */
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_REDHAT_QUMRANET, 0x1040 + VIRTIO_ID_IOMMU,
> + viommu_pci_parse_topology);
> --
> 2.28.0
>
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-09-24 15:22 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 13:15 [PATCH v3 0/6] Add virtio-iommu built-in topology Jean-Philippe Brucker
2020-08-21 13:15 ` [PATCH v3 1/6] iommu/virtio: Move to drivers/iommu/virtio/ Jean-Philippe Brucker
2020-09-04 15:29 ` Auger Eric
2020-08-21 13:15 ` [PATCH v3 2/6] iommu/virtio: Add topology helpers Jean-Philippe Brucker
2020-09-04 16:22 ` Auger Eric
2020-09-24 8:31 ` Jean-Philippe Brucker
2020-08-21 13:15 ` [PATCH v3 3/6] PCI: Add DMA configuration for virtual platforms Jean-Philippe Brucker
2020-08-21 13:15 ` [PATCH v3 4/6] iommu/virtio: Add topology definitions Jean-Philippe Brucker
2020-09-04 15:30 ` Auger Eric
2020-08-21 13:15 ` [PATCH v3 5/6] iommu/virtio: Support topology description in config space Jean-Philippe Brucker
2020-09-04 16:05 ` Auger Eric
2020-09-24 8:33 ` Jean-Philippe Brucker
2020-09-24 15:22 ` Bjorn Helgaas [this message]
2020-09-25 8:12 ` Jean-Philippe Brucker
2020-09-25 15:34 ` Bjorn Helgaas
2020-08-21 13:15 ` [PATCH v3 6/6] iommu/virtio: Enable x86 support Jean-Philippe Brucker
2020-08-26 13:26 ` [PATCH v3 0/6] Add virtio-iommu built-in topology Michael S. Tsirkin
2020-08-27 8:01 ` Jean-Philippe Brucker
2020-09-04 16:24 ` Auger Eric
2020-09-24 9:00 ` Michael S. Tsirkin
2020-09-24 9:21 ` Joerg Roedel
2020-09-24 9:38 ` Michael S. Tsirkin
2020-09-24 9:54 ` Auger Eric
2020-09-29 17:28 ` Al Stone
2020-10-02 18:23 ` Al Stone
2020-10-06 15:23 ` Auger Eric
2020-11-03 20:09 ` Al Stone
2020-11-04 9:33 ` Jean-Philippe Brucker
2020-11-04 20:56 ` Al Stone
2020-09-24 10:02 ` Joerg Roedel
2020-09-24 10:24 ` Gerd Hoffmann
2020-09-24 10:29 ` Jean-Philippe Brucker
2020-09-24 11:50 ` Joerg Roedel
2020-09-24 12:41 ` Michael S. Tsirkin
2020-09-24 12:50 ` Joerg Roedel
2020-09-25 10:22 ` Michael S. Tsirkin
2020-09-25 8:48 ` Jean-Philippe Brucker
2020-09-25 10:22 ` Michael S. Tsirkin
2020-09-25 11:26 ` Jean-Philippe Brucker
2020-09-25 13:44 ` Michael S. Tsirkin
2020-09-25 14:14 ` [virtio-dev] " Gerd Hoffmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200924152203.GA2320481@bjorn-Precision-5520 \
--to=helgaas@kernel.org \
--cc=bhelgaas@google.com \
--cc=iommu@lists.linux-foundation.org \
--cc=jasowang@redhat.com \
--cc=jean-philippe@linaro.org \
--cc=kevin.tian@intel.com \
--cc=linux-pci@vger.kernel.org \
--cc=mst@redhat.com \
--cc=sebastien.boeuf@intel.com \
--cc=virtio-dev@lists.oasis-open.org \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).