| Message ID | 20200821131540.2801801-6-jean-philippe@linaro.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | Add virtio-iommu built-in topology | expand |
Hi Jean, On 8/21/20 3:15 PM, 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. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > --- > drivers/iommu/Kconfig | 12 ++ > drivers/iommu/virtio/Makefile | 1 + > drivers/iommu/virtio/topology.c | 259 ++++++++++++++++++++++++++++++++ > 3 files changed, 272 insertions(+) > create mode 100644 drivers/iommu/virtio/topology.c > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index e29ae50f7100..98d28fdbc19a 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -394,4 +394,16 @@ config VIRTIO_IOMMU > config VIRTIO_IOMMU_TOPOLOGY_HELPERS > bool > > +config VIRTIO_IOMMU_TOPOLOGY > + bool "Handle topology properties from the virtio-iommu" > + depends on VIRTIO_IOMMU > + depends on PCI > + default y > + select VIRTIO_IOMMU_TOPOLOGY_HELPERS > + help > + Enable early probing of virtio-iommu devices 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/virtio/Makefile b/drivers/iommu/virtio/Makefile > index b42ad47eac7e..1eda8ca1cbbf 100644 > --- a/drivers/iommu/virtio/Makefile > +++ b/drivers/iommu/virtio/Makefile > @@ -1,3 +1,4 @@ > # SPDX-License-Identifier: GPL-2.0 > obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o > +obj-$(CONFIG_VIRTIO_IOMMU_TOPOLOGY) += topology.o > obj-$(CONFIG_VIRTIO_IOMMU_TOPOLOGY_HELPERS) += topology-helpers.o > diff --git a/drivers/iommu/virtio/topology.c b/drivers/iommu/virtio/topology.c > new file mode 100644 > index 000000000000..4923eec618b9 > --- /dev/null > +++ b/drivers/iommu/virtio/topology.c > @@ -0,0 +1,259 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > +#include <linux/io-64-nonatomic-hi-lo.h> > +#include <linux/iopoll.h> > +#include <linux/list.h> > +#include <linux/pci.h> > +#include <linux/virtio_ids.h> > +#include <linux/virtio_pci.h> > +#include <uapi/linux/virtio_config.h> > +#include <uapi/linux/virtio_iommu.h> > + > +#include "topology-helpers.h" > + > +struct viommu_cap_config { > + u8 bar; > + u32 length; /* structure size */ > + u32 offset; /* structure offset within the bar */ > +}; > + > +struct viommu_topo_header { > + u8 type; > + u8 reserved; > + u16 length; > +}; > + > +static struct virt_topo_endpoint * > +viommu_parse_node(void __iomem *buf, size_t len) > +{ > + int ret = -EINVAL; > + union { > + struct viommu_topo_header hdr; > + struct virtio_iommu_topo_pci_range pci; > + struct virtio_iommu_topo_mmio mmio; > + } __iomem *cfg = buf; > + struct virt_topo_endpoint *spec; > + > + spec = kzalloc(sizeof(*spec), GFP_KERNEL); > + if (!spec) > + return ERR_PTR(-ENOMEM); > + > + switch (ioread8(&cfg->hdr.type)) { > + case VIRTIO_IOMMU_TOPO_PCI_RANGE: > + if (len < sizeof(cfg->pci)) > + goto err_free; > + > + spec->dev_id.type = VIRT_TOPO_DEV_TYPE_PCI; > + spec->dev_id.segment = ioread16(&cfg->pci.segment); > + spec->dev_id.bdf_start = ioread16(&cfg->pci.bdf_start); > + spec->dev_id.bdf_end = ioread16(&cfg->pci.bdf_end); > + spec->endpoint_id = ioread32(&cfg->pci.endpoint_start); > + break; > + case VIRTIO_IOMMU_TOPO_MMIO: > + if (len < sizeof(cfg->mmio)) > + goto err_free; > + > + spec->dev_id.type = VIRT_TOPO_DEV_TYPE_MMIO; > + spec->dev_id.base = ioread64(&cfg->mmio.address); > + spec->endpoint_id = ioread32(&cfg->mmio.endpoint); > + break; > + default: > + pr_warn("unhandled format 0x%x\n", ioread8(&cfg->hdr.type)); > + ret = 0; > + goto err_free; > + } > + return spec; > + > +err_free: > + kfree(spec); > + return ERR_PTR(ret); > +} > + > +static int viommu_parse_topology(struct device *dev, > + struct virtio_iommu_config __iomem *cfg, > + size_t max_len) > +{ > + int ret; > + u16 len; > + size_t i; > + LIST_HEAD(endpoints); > + size_t offset, count; > + struct virt_topo_iommu *viommu; > + struct virt_topo_endpoint *ep, *next; > + struct viommu_topo_header __iomem *cur; > + > + offset = ioread16(&cfg->topo_config.offset); > + count = ioread16(&cfg->topo_config.count); > + if (!offset || !count) > + return 0; > + > + viommu = kzalloc(sizeof(*viommu), GFP_KERNEL); > + if (!viommu) > + return -ENOMEM; > + > + viommu->dev = dev; > + > + for (i = 0; i < count; i++, offset += len) { > + if (offset + sizeof(*cur) > max_len) { > + ret = -EOVERFLOW; > + goto err_free; > + } > + > + cur = (void __iomem *)cfg + offset; > + len = ioread16(&cur->length); > + if (offset + len > max_len) { > + ret = -EOVERFLOW; > + goto err_free; > + } > + > + ep = viommu_parse_node((void __iomem *)cur, len); > + if (!ep) { > + continue; > + } else if (IS_ERR(ep)) { > + ret = PTR_ERR(ep); > + goto err_free; > + } > + > + ep->viommu = viommu; > + list_add(&ep->list, &endpoints); > + } > + > + list_for_each_entry_safe(ep, next, &endpoints, list) > + /* Moves ep to the helpers list */ > + virt_topo_add_endpoint(ep); > + virt_topo_add_iommu(viommu); > + > + return 0; > +err_free: > + list_for_each_entry_safe(ep, next, &endpoints, list) > + kfree(ep); > + kfree(viommu); > + return ret; > +} > + > +#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) not sure the inline is useful here > +{ > + 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 int viommu_pci_reset(struct virtio_pci_common_cfg __iomem *cfg) > +{ > + u8 status; > + ktime_t timeout = ktime_add_ms(ktime_get(), 100); > + > + iowrite8(0, &cfg->device_status); > + while ((status = ioread8(&cfg->device_status)) != 0 && > + ktime_before(ktime_get(), timeout)) > + msleep(1); > + > + return status ? -ETIMEDOUT : 0; > +} > + > +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"); > + 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); > + 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); > Reviewed-by: Eric Auger <eric.auger@redhat.com> Eric
On Fri, Sep 04, 2020 at 06:05:35PM +0200, Auger Eric wrote: > > +static inline int viommu_pci_find_capability(struct pci_dev *dev, u8 cfg_type, > > + struct viommu_cap_config *cap) > not sure the inline is useful here No, I'll drop it Thanks, Jean
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 >
On Thu, Sep 24, 2020 at 10:22:03AM -0500, Bjorn Helgaas wrote: > 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. At this point we know that this is a (modern) virtio-pci device which, according to the virtio 1.0 specification, must have this capability. So this is definitely an error, but the topology description is an optional feature. > > Maybe a hint about what "common capability" means? Yes, "virtio-pci common configuration capability" would be more appropriate > > > + 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? Yes it's the virtio reset - writing 0 to the status register in the BAR. Thanks, Jean
On Fri, Sep 25, 2020 at 10:12:43AM +0200, Jean-Philippe Brucker wrote: > On Thu, Sep 24, 2020 at 10:22:03AM -0500, Bjorn Helgaas wrote: > > On Fri, Aug 21, 2020 at 03:15:39PM +0200, Jean-Philippe Brucker wrote: > > > + /* 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? > > Yes it's the virtio reset - writing 0 to the status register in the BAR. I wonder if this should be named something like viommu_virtio_reset(), so there's no confusion with PCI resets and all the timing restrictions, config space restoration, etc. associated with them. Bjorn
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index e29ae50f7100..98d28fdbc19a 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -394,4 +394,16 @@ config VIRTIO_IOMMU config VIRTIO_IOMMU_TOPOLOGY_HELPERS bool +config VIRTIO_IOMMU_TOPOLOGY + bool "Handle topology properties from the virtio-iommu" + depends on VIRTIO_IOMMU + depends on PCI + default y + select VIRTIO_IOMMU_TOPOLOGY_HELPERS + help + Enable early probing of virtio-iommu devices 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/virtio/Makefile b/drivers/iommu/virtio/Makefile index b42ad47eac7e..1eda8ca1cbbf 100644 --- a/drivers/iommu/virtio/Makefile +++ b/drivers/iommu/virtio/Makefile @@ -1,3 +1,4 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o +obj-$(CONFIG_VIRTIO_IOMMU_TOPOLOGY) += topology.o obj-$(CONFIG_VIRTIO_IOMMU_TOPOLOGY_HELPERS) += topology-helpers.o diff --git a/drivers/iommu/virtio/topology.c b/drivers/iommu/virtio/topology.c new file mode 100644 index 000000000000..4923eec618b9 --- /dev/null +++ b/drivers/iommu/virtio/topology.c @@ -0,0 +1,259 @@ +// SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/io-64-nonatomic-hi-lo.h> +#include <linux/iopoll.h> +#include <linux/list.h> +#include <linux/pci.h> +#include <linux/virtio_ids.h> +#include <linux/virtio_pci.h> +#include <uapi/linux/virtio_config.h> +#include <uapi/linux/virtio_iommu.h> + +#include "topology-helpers.h" + +struct viommu_cap_config { + u8 bar; + u32 length; /* structure size */ + u32 offset; /* structure offset within the bar */ +}; + +struct viommu_topo_header { + u8 type; + u8 reserved; + u16 length; +}; + +static struct virt_topo_endpoint * +viommu_parse_node(void __iomem *buf, size_t len) +{ + int ret = -EINVAL; + union { + struct viommu_topo_header hdr; + struct virtio_iommu_topo_pci_range pci; + struct virtio_iommu_topo_mmio mmio; + } __iomem *cfg = buf; + struct virt_topo_endpoint *spec; + + spec = kzalloc(sizeof(*spec), GFP_KERNEL); + if (!spec) + return ERR_PTR(-ENOMEM); + + switch (ioread8(&cfg->hdr.type)) { + case VIRTIO_IOMMU_TOPO_PCI_RANGE: + if (len < sizeof(cfg->pci)) + goto err_free; + + spec->dev_id.type = VIRT_TOPO_DEV_TYPE_PCI; + spec->dev_id.segment = ioread16(&cfg->pci.segment); + spec->dev_id.bdf_start = ioread16(&cfg->pci.bdf_start); + spec->dev_id.bdf_end = ioread16(&cfg->pci.bdf_end); + spec->endpoint_id = ioread32(&cfg->pci.endpoint_start); + break; + case VIRTIO_IOMMU_TOPO_MMIO: + if (len < sizeof(cfg->mmio)) + goto err_free; + + spec->dev_id.type = VIRT_TOPO_DEV_TYPE_MMIO; + spec->dev_id.base = ioread64(&cfg->mmio.address); + spec->endpoint_id = ioread32(&cfg->mmio.endpoint); + break; + default: + pr_warn("unhandled format 0x%x\n", ioread8(&cfg->hdr.type)); + ret = 0; + goto err_free; + } + return spec; + +err_free: + kfree(spec); + return ERR_PTR(ret); +} + +static int viommu_parse_topology(struct device *dev, + struct virtio_iommu_config __iomem *cfg, + size_t max_len) +{ + int ret; + u16 len; + size_t i; + LIST_HEAD(endpoints); + size_t offset, count; + struct virt_topo_iommu *viommu; + struct virt_topo_endpoint *ep, *next; + struct viommu_topo_header __iomem *cur; + + offset = ioread16(&cfg->topo_config.offset); + count = ioread16(&cfg->topo_config.count); + if (!offset || !count) + return 0; + + viommu = kzalloc(sizeof(*viommu), GFP_KERNEL); + if (!viommu) + return -ENOMEM; + + viommu->dev = dev; + + for (i = 0; i < count; i++, offset += len) { + if (offset + sizeof(*cur) > max_len) { + ret = -EOVERFLOW; + goto err_free; + } + + cur = (void __iomem *)cfg + offset; + len = ioread16(&cur->length); + if (offset + len > max_len) { + ret = -EOVERFLOW; + goto err_free; + } + + ep = viommu_parse_node((void __iomem *)cur, len); + if (!ep) { + continue; + } else if (IS_ERR(ep)) { + ret = PTR_ERR(ep); + goto err_free; + } + + ep->viommu = viommu; + list_add(&ep->list, &endpoints); + } + + list_for_each_entry_safe(ep, next, &endpoints, list) + /* Moves ep to the helpers list */ + virt_topo_add_endpoint(ep); + virt_topo_add_iommu(viommu); + + return 0; +err_free: + list_for_each_entry_safe(ep, next, &endpoints, list) + kfree(ep); + kfree(viommu); + return ret; +} + +#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 int viommu_pci_reset(struct virtio_pci_common_cfg __iomem *cfg) +{ + u8 status; + ktime_t timeout = ktime_add_ms(ktime_get(), 100); + + iowrite8(0, &cfg->device_status); + while ((status = ioread8(&cfg->device_status)) != 0 && + ktime_before(ktime_get(), timeout)) + msleep(1); + + return status ? -ETIMEDOUT : 0; +} + +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"); + 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); + 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);
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. Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- drivers/iommu/Kconfig | 12 ++ drivers/iommu/virtio/Makefile | 1 + drivers/iommu/virtio/topology.c | 259 ++++++++++++++++++++++++++++++++ 3 files changed, 272 insertions(+) create mode 100644 drivers/iommu/virtio/topology.c