On 24.11.22 10:35:21, Dan Williams wrote:
> From: Robert Richter <[email protected]>
>
> A downstream port must be connected to a component register block.
> For restricted hosts the base address is determined from the RCRB. The
> RCRB is provided by the host's CEDT CHBS entry. Rework CEDT parser to
> get the RCRB and add code to extract the component register block from
> it.
>
> RCRB's BAR[0..1] point to the component block containing CXL subsystem
> component registers. MEMBAR extraction follows the PCI base spec here,
> esp. 64 bit extraction and memory range alignment (6.0, 7.5.1.2.1). The
> RCRB base address is cached in the cxl_dport per-host bridge so that the
> upstream port component registers can be retrieved later by an RCD
> (RCIEP) associated with the host bridge.
>
> Note: Right now the component register block is used for HDM decoder
> capability only which is optional for RCDs. If unsupported by the RCD,
> the HDM init will fail. It is future work to bypass it in this case.
>
> Co-developed-by: Terry Bowman <[email protected]>
> Signed-off-by: Terry Bowman <[email protected]>
> Signed-off-by: Robert Richter <[email protected]>
> [djbw: introduce devm_cxl_add_rch_dport()]
> Signed-off-by: Dan Williams <[email protected]>
> ---
> drivers/cxl/acpi.c | 54 ++++++++++++++++++++++++++++++++--------
> drivers/cxl/core/port.c | 42 +++++++++++++++++++++++++++----
> drivers/cxl/core/regs.c | 56
> +++++++++++++++++++++++++++++++++++++++++
> drivers/cxl/cxl.h | 16 ++++++++++++
> tools/testing/cxl/Kbuild | 1 +
> tools/testing/cxl/test/cxl.c | 10 +++++++
> tools/testing/cxl/test/mock.c | 19 ++++++++++++++
> tools/testing/cxl/test/mock.h | 3 ++
> 8 files changed, 186 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 50d82376097c..1224add13529 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -9,6 +9,8 @@
> #include "cxlpci.h"
> #include "cxl.h"
>
> +#define CXL_RCRB_SIZE SZ_8K
> +
> static unsigned long cfmws_to_decoder_flags(int restrictions)
> {
> unsigned long flags = CXL_DECODER_F_ENABLE;
> @@ -215,6 +217,11 @@ static int add_host_bridge_uport(struct device *match,
> void *arg)
> if (rc)
> return rc;
>
> + if (dport->rch) {
> + dev_info(bridge, "host supports CXL (restricted)\n");
> + return 0;
> + }
This change comes after devm_cxl_register_pci_bus() to serve the
cxl_port_to_pci_bus() in devm_cxl_port_enumerate_dports() in
cxl_port_probe(). A root port is not probed and
devm_cxl_port_enumerate_dports() will be never called, so we could
jump out before devm_cxl_register_pci_bus().
On the other side we might want to be ready to use
cxl_port_to_pci_bus() elsewhere in later changes. RCHs would not work
then.
> +
> port = devm_cxl_add_port(host, bridge, dport->component_reg_phys,
> dport);
> if (IS_ERR(port))
> @@ -228,27 +235,46 @@ static int add_host_bridge_uport(struct device *match,
> void *arg)
> struct cxl_chbs_context {
> struct device *dev;
> unsigned long long uid;
> - resource_size_t chbcr;
> + struct acpi_cedt_chbs chbs;
> };
>
> -static int cxl_get_chbcr(union acpi_subtable_headers *header, void *arg,
> - const unsigned long end)
> +static int cxl_get_chbs(union acpi_subtable_headers *header, void *arg,
> + const unsigned long end)
> {
> struct cxl_chbs_context *ctx = arg;
> struct acpi_cedt_chbs *chbs;
>
> - if (ctx->chbcr)
> + if (ctx->chbs.base)
> return 0;
>
> chbs = (struct acpi_cedt_chbs *) header;
>
> if (ctx->uid != chbs->uid)
> return 0;
> - ctx->chbcr = chbs->base;
> + ctx->chbs = *chbs;
>
> return 0;
> }
>
> +static resource_size_t cxl_get_chbcr(struct cxl_chbs_context *ctx)
> +{
> + struct acpi_cedt_chbs *chbs = &ctx->chbs;
> +
> + if (!chbs->base)
> + return CXL_RESOURCE_NONE;
> +
> + if (chbs->cxl_version != ACPI_CEDT_CHBS_VERSION_CXL11)
> + return chbs->base;
> +
> + if (chbs->length != CXL_RCRB_SIZE)
> + return CXL_RESOURCE_NONE;
> +
> + dev_dbg(ctx->dev, "RCRB found for UID %lld: %pa\n", ctx->uid,
> + &chbs->base);
> +
> + return cxl_rcrb_to_component(ctx->dev, chbs->base, CXL_RCRB_DOWNSTREAM);
> +}
> +
I have an improved version of this code which squashes cxl_get_chbcr()
into cxl_get_chbs() (basically extends the original cxl_get_chbcr()
function).
> static int add_host_bridge_dport(struct device *match, void *arg)
> {
> acpi_status status;
> @@ -258,6 +284,7 @@ static int add_host_bridge_dport(struct device *match,
> void *arg)
> struct cxl_chbs_context ctx;
> struct acpi_pci_root *pci_root;
> struct cxl_port *root_port = arg;
> + resource_size_t component_reg_phys;
> struct device *host = root_port->dev.parent;
> struct acpi_device *hb = to_cxl_host_bridge(host, match);
>
> @@ -274,21 +301,28 @@ static int add_host_bridge_dport(struct device *match,
> void *arg)
> dev_dbg(match, "UID found: %lld\n", uid);
>
> ctx = (struct cxl_chbs_context) {
> - .dev = host,
> + .dev = match,
> .uid = uid,
> };
> - acpi_table_parse_cedt(ACPI_CEDT_TYPE_CHBS, cxl_get_chbcr, &ctx);
> + acpi_table_parse_cedt(ACPI_CEDT_TYPE_CHBS, cxl_get_chbs, &ctx);
>
> - if (ctx.chbcr == 0) {
> + component_reg_phys = cxl_get_chbcr(&ctx);
> + if (component_reg_phys == CXL_RESOURCE_NONE) {
> dev_warn(match, "No CHBS found for Host Bridge (UID %lld)\n",
> uid);
> return 0;
> }
>
> - dev_dbg(match, "CHBCR found: 0x%08llx\n", (u64)ctx.chbcr);
> + dev_dbg(match, "CHBCR found: %pa\n", &component_reg_phys);
>
> pci_root = acpi_pci_find_root(hb->handle);
> bridge = pci_root->bus->bridge;
> - dport = devm_cxl_add_dport(root_port, bridge, uid, ctx.chbcr);
> + if (ctx.chbs.cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11)
> + dport = devm_cxl_add_rch_dport(root_port, bridge, uid,
> + component_reg_phys,
> + ctx.chbs.base);
Yes, this new function makes the rcrb handling much more simpler.
> + else
> + dport = devm_cxl_add_dport(root_port, bridge, uid,
> + component_reg_phys);
> if (IS_ERR(dport))
> return PTR_ERR(dport);
>
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index d225267c69bb..d9fe06e1462f 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -628,6 +628,8 @@ static struct cxl_port *cxl_port_alloc(struct device
> *uport,
> iter = to_cxl_port(iter->dev.parent);
> if (iter->host_bridge)
> port->host_bridge = iter->host_bridge;
> + else if (parent_dport->rch)
> + port->host_bridge = parent_dport->dport;
Yes, looks good. This makes the endpoint a child of a CXL root port,
not the ACPI0017 the root device.
> else
> port->host_bridge = iter->uport;
> dev_dbg(uport, "host-bridge: %s\n",
> dev_name(port->host_bridge));
> @@ -899,10 +901,15 @@ static void cxl_dport_unlink(void *data)
> sysfs_remove_link(&port->dev.kobj, link_name);
> }
>
> -static struct cxl_dport *__devm_cxl_add_dport(struct cxl_port *port,
> - struct device *dport_dev,
> - int port_id,
> - resource_size_t
> component_reg_phys)
> +enum cxl_dport_mode {
> + CXL_DPORT_VH,
> + CXL_DPORT_RCH,
> +};
> +
> +static struct cxl_dport *
> +__devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
> + int port_id, resource_size_t component_reg_phys,
> + enum cxl_dport_mode mode, resource_size_t rcrb)
> {
> char link_name[CXL_TARGET_STRLEN];
> struct cxl_dport *dport;
> @@ -932,6 +939,9 @@ static struct cxl_dport *__devm_cxl_add_dport(struct
> cxl_port *port,
> dport->port_id = port_id;
> dport->component_reg_phys = component_reg_phys;
> dport->port = port;
> + if (mode == CXL_DPORT_RCH)
> + dport->rch = true;
Alternatively an inline function could be added which checks
dport->rcrb for a valid address.
> + dport->rcrb = rcrb;
>
> cond_cxl_root_lock(port);
> rc = add_dport(port, dport);
> @@ -973,7 +983,8 @@ struct cxl_dport *devm_cxl_add_dport(struct cxl_port
> *port,
> struct cxl_dport *dport;
>
> dport = __devm_cxl_add_dport(port, dport_dev, port_id,
> - component_reg_phys);
> + component_reg_phys, CXL_DPORT_VH,
> + CXL_RESOURCE_NONE);
> if (IS_ERR(dport)) {
> dev_dbg(dport_dev, "failed to add dport to %s: %ld\n",
> dev_name(&port->dev), PTR_ERR(dport));
> @@ -986,6 +997,27 @@ struct cxl_dport *devm_cxl_add_dport(struct cxl_port
> *port,
> }
> EXPORT_SYMBOL_NS_GPL(devm_cxl_add_dport, CXL);
>
> +struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
> + struct device *dport_dev, int port_id,
> + resource_size_t component_reg_phys,
> + resource_size_t rcrb)
The documentation header is missing for that.
> +{
> + struct cxl_dport *dport;
> +
> + dport = __devm_cxl_add_dport(port, dport_dev, port_id,
> + component_reg_phys, CXL_DPORT_RCH, rcrb);
> + if (IS_ERR(dport)) {
> + dev_dbg(dport_dev, "failed to add RCH dport to %s: %ld\n",
> + dev_name(&port->dev), PTR_ERR(dport));
> + } else {
> + dev_dbg(dport_dev, "RCH dport added to %s\n",
> + dev_name(&port->dev));
> + }
> +
> + return dport;
> +}
> +EXPORT_SYMBOL_NS_GPL(devm_cxl_add_rch_dport, CXL);
> +
> static int add_ep(struct cxl_ep *new)
> {
> struct cxl_port *port = new->dport->port;
> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
> index ec178e69b18f..7c2a85dc4125 100644
> --- a/drivers/cxl/core/regs.c
> +++ b/drivers/cxl/core/regs.c
> @@ -307,3 +307,59 @@ int cxl_find_regblock(struct pci_dev *pdev, enum
> cxl_regloc_type type,
> return -ENODEV;
> }
> EXPORT_SYMBOL_NS_GPL(cxl_find_regblock, CXL);
> +
> +resource_size_t cxl_rcrb_to_component(struct device *dev,
> + resource_size_t rcrb,
> + enum cxl_rcrb which)
> +{
> + resource_size_t component_reg_phys;
> + u32 bar0, bar1;
> + void *addr;
> + u16 cmd;
> +
> + if (which == CXL_RCRB_UPSTREAM)
> + rcrb += SZ_4K;
> +
> + /*
> + * RCRB's BAR[0..1] point to component block containing CXL
> + * subsystem component registers. MEMBAR extraction follows
> + * the PCI Base spec here, esp. 64 bit extraction and memory
> + * ranges alignment (6.0, 7.5.1.2.1).
> + */
> + if (!request_mem_region(rcrb, SZ_4K, "CXL RCRB"))
> + return CXL_RESOURCE_NONE;
> + addr = ioremap(rcrb, SZ_4K);
> + if (!addr) {
> + dev_err(dev, "Failed to map region %pr\n", addr);
> + release_mem_region(rcrb, SZ_4K);
> + return CXL_RESOURCE_NONE;
> + }
> +
> + cmd = readw(addr + PCI_COMMAND);
> + bar0 = readl(addr + PCI_BASE_ADDRESS_0);
> + bar1 = readl(addr + PCI_BASE_ADDRESS_1);
> + iounmap(addr);
> + release_mem_region(rcrb, SZ_4K);
> +
> + /* sanity check */
> + if (cmd == 0xffff)
> + return CXL_RESOURCE_NONE;
The spec says offset 0 should be checked (32 bit) which is always
non-FF if implemented. This requires another read.
cmd is most of the cases also non-zero, so probably checking cmd
instead will have the same effect. Still worth changing that.
If the downstream port's rcrb is all FFs, it is a FW bug. Could be
worth a message.
> + if ((cmd & PCI_COMMAND_MEMORY) == 0)
I like the following more, but that's a flavor:
if (!(cmd & PCI_COMMAND_MEMORY))
> + return CXL_RESOURCE_NONE;
> + if (bar0 & (PCI_BASE_ADDRESS_MEM_TYPE_1M | PCI_BASE_ADDRESS_SPACE_IO))
> + return CXL_RESOURCE_NONE;
> +
> + component_reg_phys = bar0 & PCI_BASE_ADDRESS_MEM_MASK;
> + if (bar0 & PCI_BASE_ADDRESS_MEM_TYPE_64)
> + component_reg_phys |= ((u64)bar1) << 32;
> +
> + if (!component_reg_phys)
> + return CXL_RESOURCE_NONE;
> +
> + /* MEMBAR is block size (64k) aligned. */
> + if (!IS_ALIGNED(component_reg_phys, CXL_COMPONENT_REG_BLOCK_SIZE))
> + return CXL_RESOURCE_NONE;
> +
> + return component_reg_phys;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_rcrb_to_component, CXL);
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 9b33ae4b2aec..43c43d1ec069 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -223,6 +223,14 @@ enum cxl_regloc_type;
> int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
> struct cxl_register_map *map);
>
> +enum cxl_rcrb {
> + CXL_RCRB_DOWNSTREAM,
> + CXL_RCRB_UPSTREAM,
> +};
> +resource_size_t cxl_rcrb_to_component(struct device *dev,
> + resource_size_t rcrb,
> + enum cxl_rcrb which);
> +
> #define CXL_RESOURCE_NONE ((resource_size_t) -1)
> #define CXL_TARGET_STRLEN 20
>
> @@ -486,12 +494,16 @@ cxl_find_dport_by_dev(struct cxl_port *port, const
> struct device *dport_dev)
> * @dport: PCI bridge or firmware device representing the downstream link
> * @port_id: unique hardware identifier for dport in decoder target list
> * @component_reg_phys: downstream port component registers
> + * @rcrb: base address for the Root Complex Register Block
> + * @rch: Indicate whether this dport was enumerated in RCH or VH mode
> * @port: reference to cxl_port that contains this downstream port
> */
> struct cxl_dport {
> struct device *dport;
> int port_id;
> resource_size_t component_reg_phys;
> + resource_size_t rcrb;
> + bool rch;
> struct cxl_port *port;
> };
>
> @@ -561,6 +573,10 @@ bool schedule_cxl_memdev_detach(struct cxl_memdev
> *cxlmd);
> struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port,
> struct device *dport, int port_id,
> resource_size_t component_reg_phys);
> +struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
> + struct device *dport_dev, int port_id,
> + resource_size_t component_reg_phys,
> + resource_size_t rcrb);
>
> struct cxl_decoder *to_cxl_decoder(struct device *dev);
> struct cxl_root_decoder *to_cxl_root_decoder(struct device *dev);
> diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
> index 500be85729cc..9e4d94e81723 100644
> --- a/tools/testing/cxl/Kbuild
> +++ b/tools/testing/cxl/Kbuild
> @@ -10,6 +10,7 @@ ldflags-y += --wrap=devm_cxl_add_passthrough_decoder
> ldflags-y += --wrap=devm_cxl_enumerate_decoders
> ldflags-y += --wrap=cxl_await_media_ready
> ldflags-y += --wrap=cxl_hdm_decode_init
> +ldflags-y += --wrap=cxl_rcrb_to_component
>
> DRIVERS := ../../../drivers
> CXL_SRC := $(DRIVERS)/cxl
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index 42a34650dd2f..1823c61d7ba3 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -694,6 +694,15 @@ static int mock_cxl_port_enumerate_dports(struct
> cxl_port *port)
> return 0;
> }
>
> +resource_size_t mock_cxl_rcrb_to_component(struct device *dev,
> + resource_size_t rcrb,
> + enum cxl_rcrb which)
> +{
> + dev_dbg(dev, "rcrb: %pa which: %d\n", &rcrb, which);
> +
> + return 0;
> +}
> +
> static struct cxl_mock_ops cxl_mock_ops = {
> .is_mock_adev = is_mock_adev,
> .is_mock_bridge = is_mock_bridge,
> @@ -702,6 +711,7 @@ static struct cxl_mock_ops cxl_mock_ops = {
> .is_mock_dev = is_mock_dev,
> .acpi_table_parse_cedt = mock_acpi_table_parse_cedt,
> .acpi_evaluate_integer = mock_acpi_evaluate_integer,
> + .cxl_rcrb_to_component = mock_cxl_rcrb_to_component,
> .acpi_pci_find_root = mock_acpi_pci_find_root,
> .devm_cxl_port_enumerate_dports = mock_cxl_port_enumerate_dports,
> .devm_cxl_setup_hdm = mock_cxl_setup_hdm,
> diff --git a/tools/testing/cxl/test/mock.c b/tools/testing/cxl/test/mock.c
> index bce6a21df0d5..5dface08e0de 100644
> --- a/tools/testing/cxl/test/mock.c
> +++ b/tools/testing/cxl/test/mock.c
> @@ -224,6 +224,25 @@ int __wrap_cxl_hdm_decode_init(struct cxl_dev_state
> *cxlds,
> }
> EXPORT_SYMBOL_NS_GPL(__wrap_cxl_hdm_decode_init, CXL);
>
> +resource_size_t __wrap_cxl_rcrb_to_component(struct device *dev,
> + resource_size_t rcrb,
> + enum cxl_rcrb which)
> +{
> + int index;
> + resource_size_t component_reg_phys;
> + struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
> +
> + if (ops && ops->is_mock_port(dev))
> + component_reg_phys =
> + ops->cxl_rcrb_to_component(dev, rcrb, which);
> + else
> + component_reg_phys = cxl_rcrb_to_component(dev, rcrb, which);
> + put_cxl_mock_ops(index);
> +
> + return component_reg_phys;
> +}
> +EXPORT_SYMBOL_NS_GPL(__wrap_cxl_rcrb_to_component, CXL);
> +
> MODULE_LICENSE("GPL v2");
> MODULE_IMPORT_NS(ACPI);
> MODULE_IMPORT_NS(CXL);
> diff --git a/tools/testing/cxl/test/mock.h b/tools/testing/cxl/test/mock.h
> index 738f24e3988a..ef33f159375e 100644
> --- a/tools/testing/cxl/test/mock.h
> +++ b/tools/testing/cxl/test/mock.h
> @@ -15,6 +15,9 @@ struct cxl_mock_ops {
> acpi_string pathname,
> struct acpi_object_list *arguments,
> unsigned long long *data);
> + resource_size_t (*cxl_rcrb_to_component)(struct device *dev,
> + resource_size_t rcrb,
> + enum cxl_rcrb which);
> struct acpi_pci_root *(*acpi_pci_find_root)(acpi_handle handle);
> bool (*is_mock_bus)(struct pci_bus *bus);
> bool (*is_mock_port)(struct device *dev);
>
The mock part looks good to me.
-Robert
