Michael S. Tsirkin
2020-Mar-01 11:17 UTC
[PATCH v2 1/3] iommu/virtio: Add topology description to virtio-iommu config space
On Fri, Feb 28, 2020 at 06:25:36PM +0100, Jean-Philippe Brucker wrote:> Platforms without device-tree do not currently have a method for > describing the vIOMMU topology. Provide a topology description embedded > into the virtio device. > > 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. > > This solution isn't elegant nor foolproof, but is the best we can do at > the moment and works with existing virtio-iommu implementations. It also > enables an IOMMU for lightweight hypervisors that do not rely on > firmware methods for booting. > > Signed-off-by: Eric Auger <eric.auger at redhat.com> > Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org> > --- > MAINTAINERS | 2 + > drivers/iommu/Kconfig | 10 + > drivers/iommu/Makefile | 1 + > drivers/iommu/virtio-iommu-topology.c | 343 ++++++++++++++++++++++++++ > drivers/iommu/virtio-iommu.c | 3 + > include/linux/virt_iommu.h | 19 ++ > include/uapi/linux/virtio_iommu.h | 26 ++ > 7 files changed, 404 insertions(+) > create mode 100644 drivers/iommu/virtio-iommu-topology.c > create mode 100644 include/linux/virt_iommu.h > > diff --git a/MAINTAINERS b/MAINTAINERS > index fcd79fc38928..65a03ce53096 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -17781,6 +17781,8 @@ M: Jean-Philippe Brucker <jean-philippe at linaro.org> > L: virtualization at lists.linux-foundation.org > S: Maintained > F: drivers/iommu/virtio-iommu.c > +F: drivers/iommu/virtio-iommu-topology.c > +F: include/linux/virt_iommu.h > F: include/uapi/linux/virtio_iommu.h > > VIRTUAL BOX GUEST DEVICE DRIVER > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index c5df570ef84a..f8cb45d84bb0 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -516,4 +516,14 @@ config VIRTIO_IOMMU > > Say Y here if you intend to run this kernel as a guest. > > +config VIRTIO_IOMMU_TOPOLOGY > + bool "Topology properties for the virtio-iommu" > + depends on VIRTIO_IOMMU > + default y > + help > + Enable early probing of the virtio-iommu device, to detect the > + built-in topology description. > + > + Say Y here if you intend to run this kernel as a guest. > + > endif # IOMMU_SUPPORT > diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile > index 9f33fdb3bb05..5da24280d08c 100644 > --- a/drivers/iommu/Makefile > +++ b/drivers/iommu/Makefile > @@ -37,3 +37,4 @@ obj-$(CONFIG_S390_IOMMU) += s390-iommu.o > obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o > obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o > obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o > +obj-$(CONFIG_VIRTIO_IOMMU_TOPOLOGY) += virtio-iommu-topology.o > diff --git a/drivers/iommu/virtio-iommu-topology.c b/drivers/iommu/virtio-iommu-topology.c > new file mode 100644 > index 000000000000..2188624ef216 > --- /dev/null > +++ b/drivers/iommu/virtio-iommu-topology.c > @@ -0,0 +1,343 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > +#include <linux/dma-iommu.h> > +#include <linux/list.h> > +#include <linux/pci.h> > +#include <linux/virt_iommu.h> > +#include <linux/virtio_ids.h> > +#include <linux/virtio_pci.h> > +#include <uapi/linux/virtio_iommu.h> > + > +struct viommu_cap_config { > + u8 bar; > + u32 length; /* structure size */ > + u32 offset; /* structure offset within the bar */ > +}; > + > +union viommu_topo_cfg { > + __le16 type; > + struct virtio_iommu_topo_pci_range pci; > + struct virtio_iommu_topo_endpoint ep; > +}; > + > +struct viommu_spec { > + struct device *dev; /* transport device */ > + struct fwnode_handle *fwnode; > + struct iommu_ops *ops; > + struct list_head list; > + size_t num_items; > + /* The config array of length num_items follows */ > + union viommu_topo_cfg cfg[]; > +}; > + > +static LIST_HEAD(viommus); > +static DEFINE_MUTEX(viommus_lock); > + > +#define VPCI_FIELD(field) offsetof(struct virtio_pci_cap, field) > + > +static inline int viommu_pci_find_capability(struct pci_dev *dev, u8 cfg_type, > + struct viommu_cap_config *cap) > +{ > + int pos; > + u8 bar; > + > + for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); > + pos > 0; > + pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) { > + u8 type; > + > + pci_read_config_byte(dev, pos + VPCI_FIELD(cfg_type), &type); > + if (type != cfg_type) > + continue; > + > + pci_read_config_byte(dev, pos + VPCI_FIELD(bar), &bar); > + > + /* Ignore structures with reserved BAR values */ > + if (type != VIRTIO_PCI_CAP_PCI_CFG && bar > 0x5) > + continue; > + > + cap->bar = bar; > + pci_read_config_dword(dev, pos + VPCI_FIELD(length), > + &cap->length); > + pci_read_config_dword(dev, pos + VPCI_FIELD(offset), > + &cap->offset); > + > + return pos; > + } > + return 0; > +} > + > +static void viommu_ccopy(__le32 *dst, u32 __iomem *src, size_t length) > +{ > + size_t i; > + > + /* For the moment all our config structures align on 32b */ > + if (WARN_ON(length % 4)) > + return; > + > + for (i = 0; i < length / 4; i++) > + /* Keep little-endian data */ > + dst[i] = cpu_to_le32(ioread32(src + i)); > +} > + > +static int viommu_parse_topology(struct device *dev, > + struct virtio_iommu_config __iomem *cfg)why is this int? always succeeds and callers don't use the return code ...> +{ > + size_t i; > + size_t spec_length; > + struct viommu_spec *viommu_spec; > + u32 offset, item_length, num_items; > + > + offset = ioread32(&cfg->topo_config.offset); > + item_length = ioread32(&cfg->topo_config.item_length); > + num_items = ioread32(&cfg->topo_config.num_items); > + if (!offset || !num_items || !item_length) > + return 0; > + > + spec_length = sizeof(*viommu_spec) + num_items * > + sizeof(union viommu_topo_cfg);This can overflow. Worth detecting and failing init if it does?> + viommu_spec = kzalloc(spec_length, GFP_KERNEL); > + if (!viommu_spec) > + return -ENOMEM; > + > + viommu_spec->dev = dev; > + > + /* Copy in the whole array, sort it out later */ > + for (i = 0; i < num_items; i++) { > + size_t read_length = min_t(size_t, item_length, > + sizeof(union viommu_topo_cfg)); > + > + viommu_ccopy((__le32 *)&viommu_spec->cfg[i],Doesn't this need __force?> + (void __iomem *)cfg + offset, > + read_length);> + > + offset += item_length; > + } > + viommu_spec->num_items = num_items; > + > + mutex_lock(&viommus_lock); > + list_add(&viommu_spec->list, &viommus); > + mutex_unlock(&viommus_lock); > + > + return 0; > +} > + > +static void viommu_pci_parse_topology(struct pci_dev *dev) > +{ > + int pos; > + u32 features; > + void __iomem *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. > + */ > + pos = viommu_pci_find_capability(dev, VIRTIO_PCI_CAP_COMMON_CFG, &cap); > + if (!pos) { > + pci_warn(dev, "common capability not found\n"); > + return; > + } > + > + if (pci_enable_device_mem(dev)) > + return; > + > + regs = pci_iomap(dev, cap.bar, 0); > + if (!regs) > + return; > + > + common_cfg = regs + cap.offset; > +So the virtio spec says this: The driver MUST follow this sequence to initialize a device: \begin{enumerate} \item Reset the device. \item Set the ACKNOWLEDGE status bit: the guest OS has noticed the device. \item Set the DRIVER status bit: the guest OS knows how to drive the device. Let's follow this unless there's a good reason not to. And I guess let's reset at the end?> + /* Find out if the device supports topology description */ > + writel(0, &common_cfg->device_feature_select); > + features = ioread32(&common_cfg->device_feature); > + > + pci_iounmap(dev, regs); > + > + if (!(features & BIT(VIRTIO_IOMMU_F_TOPOLOGY))) { > + pci_dbg(dev, "device doesn't have topology description"); > + return; > + } > + > + pos = viommu_pci_find_capability(dev, VIRTIO_PCI_CAP_DEVICE_CFG, &cap); > + if (!pos) { > + pci_warn(dev, "device config capability not found\n"); > + return; > + } > + > + regs = pci_iomap(dev, cap.bar, 0); > + if (!regs) > + return; > + > + pci_info(dev, "parsing virtio-iommu topology\n"); > + viommu_parse_topology(&dev->dev, regs + cap.offset); > + pci_iounmap(dev, 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); > + > +/* > + * Return true if the device matches this topology structure. Write the endpoint > + * ID into epid if it's the case. > + */ > +static bool viommu_parse_pci(struct pci_dev *pdev, union viommu_topo_cfg *cfg, > + u32 *epid) > +{ > + u32 endpoint_start; > + u16 start, end, domain; > + u16 devid = pci_dev_id(pdev); > + u16 type = le16_to_cpu(cfg->type); > + > + if (type != VIRTIO_IOMMU_TOPO_PCI_RANGE) > + return false; > + > + start = le16_to_cpu(cfg->pci.requester_start); > + end = le16_to_cpu(cfg->pci.requester_end); > + domain = le16_to_cpu(cfg->pci.hierarchy); > + endpoint_start = le32_to_cpu(cfg->pci.endpoint_start); > + > + if (pci_domain_nr(pdev->bus) == domain && > + devid >= start && devid <= end) { > + *epid = devid - start + endpoint_start; > + return true; > + } > + return false; > +} > + > +static const struct iommu_ops *virt_iommu_setup(struct device *dev) > +{ > + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); > + const struct iommu_ops *viommu_ops = NULL; > + struct fwnode_handle *viommu_fwnode; > + struct viommu_spec *viommu_spec; > + struct pci_dev *pci_dev = NULL; > + struct device *viommu_dev; > + bool found = false; > + size_t i; > + u32 epid; > + int ret; > + > + /* Already translated? */ > + if (fwspec && fwspec->ops) > + return NULL; > + > + if (dev_is_pci(dev)) { > + pci_dev = to_pci_dev(dev); > + } else { > + /* At the moment we don't support platform devices */ > + return NULL; > + } > + > + mutex_lock(&viommus_lock); > + list_for_each_entry(viommu_spec, &viommus, list) { > + for (i = 0; i < viommu_spec->num_items; i++) { > + union viommu_topo_cfg *cfg = &viommu_spec->cfg[i]; > + > + found = viommu_parse_pci(pci_dev, cfg, &epid); > + if (found) > + break; > + } > + if (found) { > + viommu_ops = viommu_spec->ops; > + viommu_fwnode = viommu_spec->fwnode; > + viommu_dev = viommu_spec->dev; > + break; > + } > + } > + mutex_unlock(&viommus_lock); > + if (!found) > + return NULL; > + > + /* We're not translating ourselves. */ > + if (viommu_dev == dev) > + return NULL; > + > + /* > + * If we found a PCI range managed by the viommu, we're the ones that > + * have to request ACS. > + */ > + if (pci_dev) > + pci_request_acs(); > + > + if (!viommu_ops) > + return ERR_PTR(-EPROBE_DEFER); > + > + ret = iommu_fwspec_init(dev, viommu_fwnode, viommu_ops); > + if (ret) > + return ERR_PTR(ret); > + > + iommu_fwspec_add_ids(dev, &epid, 1); > + > + return viommu_ops; > +} > + > +/** > + * virt_dma_configure - Configure DMA of virtualized devices > + * @dev: the endpoint > + * > + * Setup the DMA and IOMMU ops of a virtual device, for platforms without DT or > + * ACPI. > + * > + * Return: -EPROBE_DEFER if the device is managed by an IOMMU that hasn't been > + * probed yet, 0 otherwise > + */ > +int virt_dma_configure(struct device *dev) > +{ > + const struct iommu_ops *iommu_ops; > + > + iommu_ops = virt_iommu_setup(dev); > + if (IS_ERR_OR_NULL(iommu_ops)) { > + int ret = PTR_ERR(iommu_ops); > + > + if (ret == -EPROBE_DEFER || ret == 0) > + return ret; > + dev_err(dev, "error %d while setting up virt IOMMU\n", ret); > + return 0; > + } > + > + /* > + * If we have reason to believe the IOMMU driver missed the initial > + * add_device callback for dev, replay it to get things in order. > + */ > + if (dev->bus && !device_iommu_mapped(dev)) > + iommu_probe_device(dev); > + > + /* Assume coherent, as well as full 64-bit addresses. */ > +#ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS > + arch_setup_dma_ops(dev, 0, ~0ULL, iommu_ops, true); > +#else > + iommu_setup_dma_ops(dev, 0, ~0ULL); > +#endif > + return 0; > +} > + > +/** > + * virt_set_iommu_ops - Set the IOMMU ops of a virtual IOMMU device > + * @dev: the IOMMU device (transport) > + * @ops: the new IOMMU ops or NULL > + * > + * Setup the iommu_ops associated to a viommu_spec, once the driver is loaded > + * and the device probed. > + */ > +void virt_set_iommu_ops(struct device *dev, struct iommu_ops *ops) > +{ > + struct viommu_spec *viommu_spec; > + > + mutex_lock(&viommus_lock); > + list_for_each_entry(viommu_spec, &viommus, list) { > + if (viommu_spec->dev == dev) { > + viommu_spec->ops = ops; > + viommu_spec->fwnode = ops ? dev->fwnode : NULL; > + break; > + } > + } > + mutex_unlock(&viommus_lock); > +} > +EXPORT_SYMBOL_GPL(virt_set_iommu_ops); > diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c > index 93ff58632452..5429c12c879b 100644 > --- a/drivers/iommu/virtio-iommu.c > +++ b/drivers/iommu/virtio-iommu.c > @@ -21,6 +21,7 @@ > #include <linux/virtio.h> > #include <linux/virtio_config.h> > #include <linux/virtio_ids.h> > +#include <linux/virt_iommu.h> > #include <linux/wait.h> > > #include <uapi/linux/virtio_iommu.h> > @@ -1075,6 +1076,7 @@ static int viommu_probe(struct virtio_device *vdev) > if (ret) > goto err_free_vqs; > > + virt_set_iommu_ops(dev->parent, &viommu_ops); > iommu_device_set_ops(&viommu->iommu, &viommu_ops); > iommu_device_set_fwnode(&viommu->iommu, parent_dev->fwnode); > > @@ -1121,6 +1123,7 @@ static void viommu_remove(struct virtio_device *vdev) > { > struct viommu_dev *viommu = vdev->priv; > > + virt_set_iommu_ops(vdev->dev.parent, NULL); > iommu_device_sysfs_remove(&viommu->iommu); > iommu_device_unregister(&viommu->iommu); > > diff --git a/include/linux/virt_iommu.h b/include/linux/virt_iommu.h > new file mode 100644 > index 000000000000..c68b03ec75ba > --- /dev/null > +++ b/include/linux/virt_iommu.h > @@ -0,0 +1,19 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef VIRTIO_IOMMU_H_ > +#define VIRTIO_IOMMU_H_ > + > +#if IS_ENABLED(CONFIG_VIRTIO_IOMMU_TOPOLOGY) > +int virt_dma_configure(struct device *dev); > +void virt_set_iommu_ops(struct device *dev, struct iommu_ops *ops); > +#else /* !CONFIG_VIRTIO_IOMMU_TOPOLOGY */ > +static inline int virt_dma_configure(struct device *dev) > +{ > + /* Don't disturb the normal DMA configuration methods */ > + return 0; > +} > + > +static inline void virt_set_iommu_ops(struct device *dev, struct iommu_ops *ops) > +{ } > +#endif /* !CONFIG_VIRTIO_IOMMU_TOPOLOGY */ > + > +#endif /* VIRTIO_IOMMU_H_ */ > diff --git a/include/uapi/linux/virtio_iommu.h b/include/uapi/linux/virtio_iommu.h > index 237e36a280cb..ec57d215086a 100644 > --- a/include/uapi/linux/virtio_iommu.h > +++ b/include/uapi/linux/virtio_iommu.h > @@ -16,6 +16,7 @@ > #define VIRTIO_IOMMU_F_BYPASS 3 > #define VIRTIO_IOMMU_F_PROBE 4 > #define VIRTIO_IOMMU_F_MMIO 5 > +#define VIRTIO_IOMMU_F_TOPOLOGY 6 > > struct virtio_iommu_range_64 { > __le64 start; > @@ -27,6 +28,12 @@ struct virtio_iommu_range_32 { > __le32 end; > }; > > +struct virtio_iommu_topo_config { > + __le32 offset; > + __le32 num_items; > + __le32 item_length; > +}; > + > struct virtio_iommu_config { > /* Supported page sizes */ > __le64 page_size_mask; > @@ -36,6 +43,25 @@ struct virtio_iommu_config { > struct virtio_iommu_range_32 domain_range; > /* Probe buffer size */ > __le32 probe_size; > + struct virtio_iommu_topo_config topo_config; > +}; > + > +#define VIRTIO_IOMMU_TOPO_PCI_RANGE 0x1 > +#define VIRTIO_IOMMU_TOPO_ENDPOINT 0x2 > + > +struct virtio_iommu_topo_pci_range { > + __le16 type; > + __le16 hierarchy; > + __le16 requester_start; > + __le16 requester_end; > + __le32 endpoint_start; > +}; > + > +struct virtio_iommu_topo_endpoint { > + __le16 type; > + __le16 reserved; > + __le32 endpoint; > + __le64 address; > }; > > /* Request types */ > -- > 2.25.0