ocxl: Driver code for 'generic' opencapi devices
Add an ocxl driver to handle generic opencapi devices. Of course, it's
not meant to be the only opencapi driver, any device is free to
implement its own. But if a host application only needs basic services
like attaching to an opencapi adapter, have translation faults handled
or allocate AFU interrupts, it should suffice.
The AFU config space must follow the opencapi specification and use
the expected vendor/device ID to be seen by the generic driver.
The driver exposes the device AFUs as a char device in /dev/ocxl/
Note that the driver currently doesn't handle memory attached to the
opencapi device.
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
new file mode 100644
index 0000000..64d7a98
--- /dev/null
+++ b/drivers/misc/ocxl/link.c
@@ -0,0 +1,603 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright 2017 IBM Corp.
+#include <linux/sched/mm.h>
+#include <linux/mutex.h>
+#include <linux/mmu_context.h>
+#include <asm/copro.h>
+#include <asm/pnv-ocxl.h>
+#include "ocxl_internal.h"
+
+
+#define SPA_PASID_BITS 15
+#define SPA_PASID_MAX ((1 << SPA_PASID_BITS) - 1)
+#define SPA_PE_MASK SPA_PASID_MAX
+#define SPA_SPA_SIZE_LOG 22 /* Each SPA is 4 Mb */
+
+#define SPA_CFG_SF (1ull << (63-0))
+#define SPA_CFG_TA (1ull << (63-1))
+#define SPA_CFG_HV (1ull << (63-3))
+#define SPA_CFG_UV (1ull << (63-4))
+#define SPA_CFG_XLAT_hpt (0ull << (63-6)) /* Hashed page table (HPT) mode */
+#define SPA_CFG_XLAT_roh (2ull << (63-6)) /* Radix on HPT mode */
+#define SPA_CFG_XLAT_ror (3ull << (63-6)) /* Radix on Radix mode */
+#define SPA_CFG_PR (1ull << (63-49))
+#define SPA_CFG_TC (1ull << (63-54))
+#define SPA_CFG_DR (1ull << (63-59))
+
+#define SPA_XSL_TF (1ull << (63-3)) /* Translation fault */
+#define SPA_XSL_S (1ull << (63-38)) /* Store operation */
+
+#define SPA_PE_VALID 0x80000000
+
+
+struct pe_data {
+ struct mm_struct *mm;
+ /* callback to trigger when a translation fault occurs */
+ void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr);
+ /* opaque pointer to be passed to the above callback */
+ void *xsl_err_data;
+ struct rcu_head rcu;
+};
+
+struct spa {
+ struct ocxl_process_element *spa_mem;
+ int spa_order;
+ struct mutex spa_lock;
+ struct radix_tree_root pe_tree; /* Maps PE handles to pe_data */
+ char *irq_name;
+ int virq;
+ void __iomem *reg_dsisr;
+ void __iomem *reg_dar;
+ void __iomem *reg_tfc;
+ void __iomem *reg_pe_handle;
+ /*
+ * The following field are used by the memory fault
+ * interrupt handler. We can only have one interrupt at a
+ * time. The NPU won't raise another interrupt until the
+ * previous one has been ack'd by writing to the TFC register
+ */
+ struct xsl_fault {
+ struct work_struct fault_work;
+ u64 pe;
+ u64 dsisr;
+ u64 dar;
+ struct pe_data pe_data;
+ } xsl_fault;
+};
+
+/*
+ * A opencapi link can be used be by several PCI functions. We have
+ * one link per device slot.
+ *
+ * A linked list of opencapi links should suffice, as there's a
+ * limited number of opencapi slots on a system and lookup is only
+ * done when the device is probed
+ */
+struct link {
+ struct list_head list;
+ struct kref ref;
+ int domain;
+ int bus;
+ int dev;
+ atomic_t irq_available;
+ struct spa *spa;
+ void *platform_data;
+};
+static struct list_head links_list = LIST_HEAD_INIT(links_list);
+static DEFINE_MUTEX(links_list_lock);
+
+enum xsl_response {
+ CONTINUE,
+ ADDRESS_ERROR,
+ RESTART,
+};
+
+
+static void read_irq(struct spa *spa, u64 *dsisr, u64 *dar, u64 *pe)
+{
+ u64 reg;
+
+ *dsisr = in_be64(spa->reg_dsisr);
+ *dar = in_be64(spa->reg_dar);
+ reg = in_be64(spa->reg_pe_handle);
+ *pe = reg & SPA_PE_MASK;
+}
+
+static void ack_irq(struct spa *spa, enum xsl_response r)
+{
+ u64 reg = 0;
+
+ /* continue is not supported */
+ if (r == RESTART)
+ reg = PPC_BIT(31);
+ else if (r == ADDRESS_ERROR)
+ reg = PPC_BIT(30);
+ else
+ WARN(1, "Invalid irq response %d\n", r);
+
+ if (reg)
+ out_be64(spa->reg_tfc, reg);
+}
+
+static void xsl_fault_handler_bh(struct work_struct *fault_work)
+{
+ unsigned int flt = 0;
+ unsigned long access, flags, inv_flags = 0;
+ enum xsl_response r;
+ struct xsl_fault *fault = container_of(fault_work, struct xsl_fault,
+ fault_work);
+ struct spa *spa = container_of(fault, struct spa, xsl_fault);
+
+ int rc;
+
+ /*
+ * We need to release a reference on the mm whenever exiting this
+ * function (taken in the memory fault interrupt handler)
+ */
+ rc = copro_handle_mm_fault(fault->pe_data.mm, fault->dar, fault->dsisr,
+ &flt);
+ if (rc) {
+ pr_debug("copro_handle_mm_fault failed: %d\n", rc);
+ if (fault->pe_data.xsl_err_cb) {
+ fault->pe_data.xsl_err_cb(
+ fault->pe_data.xsl_err_data,
+ fault->dar, fault->dsisr);
+ }
+ r = ADDRESS_ERROR;
+ goto ack;
+ }
+
+ if (!radix_enabled()) {
+ /*
+ * update_mmu_cache() will not have loaded the hash
+ * since current->trap is not a 0x400 or 0x300, so
+ * just call hash_page_mm() here.
+ */
+ access = _PAGE_PRESENT | _PAGE_READ;
+ if (fault->dsisr & SPA_XSL_S)
+ access |= _PAGE_WRITE;
+
+ if (REGION_ID(fault->dar) != USER_REGION_ID)
+ access |= _PAGE_PRIVILEGED;
+
+ local_irq_save(flags);
+ hash_page_mm(fault->pe_data.mm, fault->dar, access, 0x300,
+ inv_flags);
+ local_irq_restore(flags);
+ }
+ r = RESTART;
+ack:
+ mmdrop(fault->pe_data.mm);
+ ack_irq(spa, r);
+}
+
+static irqreturn_t xsl_fault_handler(int irq, void *data)
+{
+ struct link *link = (struct link *) data;
+ struct spa *spa = link->spa;
+ u64 dsisr, dar, pe_handle;
+ struct pe_data *pe_data;
+ struct ocxl_process_element *pe;
+ int lpid, pid, tid;
+
+ read_irq(spa, &dsisr, &dar, &pe_handle);
+
+ WARN_ON(pe_handle > SPA_PE_MASK);
+ pe = spa->spa_mem + pe_handle;
+ lpid = be32_to_cpu(pe->lpid);
+ pid = be32_to_cpu(pe->pid);
+ tid = be32_to_cpu(pe->tid);
+ /* We could be reading all null values here if the PE is being
+ * removed while an interrupt kicks in. It's not supposed to
+ * happen if the driver notified the AFU to terminate the
+ * PASID, and the AFU waited for pending operations before
+ * acknowledging. But even if it happens, we won't find a
+ * memory context below and fail silently, so it should be ok.
+ */
+ if (!(dsisr & SPA_XSL_TF)) {
+ WARN(1, "Invalid xsl interrupt fault register %#llx\n", dsisr);
+ ack_irq(spa, ADDRESS_ERROR);
+ return IRQ_HANDLED;
+ }
+
+ rcu_read_lock();
+ pe_data = radix_tree_lookup(&spa->pe_tree, pe_handle);
+ if (!pe_data) {
+ /*
+ * Could only happen if the driver didn't notify the
+ * AFU about PASID termination before removing the PE,
+ * or the AFU didn't wait for all memory access to
+ * have completed.
+ *
+ * Either way, we fail early, but we shouldn't log an
+ * error message, as it is a valid (if unexpected)
+ * scenario
+ */
+ rcu_read_unlock();
+ pr_debug("Unknown mm context for xsl interrupt\n");
+ ack_irq(spa, ADDRESS_ERROR);
+ return IRQ_HANDLED;
+ }
+ WARN_ON(pe_data->mm->context.id != pid);
+
+ spa->xsl_fault.pe = pe_handle;
+ spa->xsl_fault.dar = dar;
+ spa->xsl_fault.dsisr = dsisr;
+ spa->xsl_fault.pe_data = *pe_data;
+ mmgrab(pe_data->mm); /* mm count is released by bottom half */
+
+ rcu_read_unlock();
+ schedule_work(&spa->xsl_fault.fault_work);
+ return IRQ_HANDLED;
+}
+
+static void unmap_irq_registers(struct spa *spa)
+{
+ pnv_ocxl_unmap_xsl_regs(spa->reg_dsisr, spa->reg_dar, spa->reg_tfc,
+ spa->reg_pe_handle);
+}
+
+static int map_irq_registers(struct pci_dev *dev, struct spa *spa)
+{
+ return pnv_ocxl_map_xsl_regs(dev, &spa->reg_dsisr, &spa->reg_dar,
+ &spa->reg_tfc, &spa->reg_pe_handle);
+}
+
+static int setup_xsl_irq(struct pci_dev *dev, struct link *link)
+{
+ struct spa *spa = link->spa;
+ int rc;
+ int hwirq;
+
+ rc = pnv_ocxl_get_xsl_irq(dev, &hwirq);
+ if (rc)
+ return rc;
+
+ rc = map_irq_registers(dev, spa);
+ if (rc)
+ return rc;
+
+ spa->irq_name = kasprintf(GFP_KERNEL, "ocxl-xsl-%x-%x-%x",
+ link->domain, link->bus, link->dev);
+ if (!spa->irq_name) {
+ unmap_irq_registers(spa);
+ dev_err(&dev->dev, "Can't allocate name for xsl interrupt\n");
+ return -ENOMEM;
+ }
+ /*
+ * At some point, we'll need to look into allowing a higher
+ * number of interrupts. Could we have an IRQ domain per link?
+ */
+ spa->virq = irq_create_mapping(NULL, hwirq);
+ if (!spa->virq) {
+ kfree(spa->irq_name);
+ unmap_irq_registers(spa);
+ dev_err(&dev->dev,
+ "irq_create_mapping failed for translation interrupt\n");
+ return -EINVAL;
+ }
+
+ dev_dbg(&dev->dev, "hwirq %d mapped to virq %d\n", hwirq, spa->virq);
+
+ rc = request_irq(spa->virq, xsl_fault_handler, 0, spa->irq_name,
+ link);
+ if (rc) {
+ irq_dispose_mapping(spa->virq);
+ kfree(spa->irq_name);
+ unmap_irq_registers(spa);
+ dev_err(&dev->dev,
+ "request_irq failed for translation interrupt: %d\n",
+ rc);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static void release_xsl_irq(struct link *link)
+{
+ struct spa *spa = link->spa;
+
+ if (spa->virq) {
+ free_irq(spa->virq, link);
+ irq_dispose_mapping(spa->virq);
+ }
+ kfree(spa->irq_name);
+ unmap_irq_registers(spa);
+}
+
+static int alloc_spa(struct pci_dev *dev, struct link *link)
+{
+ struct spa *spa;
+
+ spa = kzalloc(sizeof(struct spa), GFP_KERNEL);
+ if (!spa)
+ return -ENOMEM;
+
+ mutex_init(&spa->spa_lock);
+ INIT_RADIX_TREE(&spa->pe_tree, GFP_KERNEL);
+ INIT_WORK(&spa->xsl_fault.fault_work, xsl_fault_handler_bh);
+
+ spa->spa_order = SPA_SPA_SIZE_LOG - PAGE_SHIFT;
+ spa->spa_mem = (struct ocxl_process_element *)
+ __get_free_pages(GFP_KERNEL | __GFP_ZERO, spa->spa_order);
+ if (!spa->spa_mem) {
+ dev_err(&dev->dev, "Can't allocate Shared Process Area\n");
+ kfree(spa);
+ return -ENOMEM;
+ }
+ pr_debug("Allocated SPA for %x:%x:%x at %p\n", link->domain, link->bus,
+ link->dev, spa->spa_mem);
+
+ link->spa = spa;
+ return 0;
+}
+
+static void free_spa(struct link *link)
+{
+ struct spa *spa = link->spa;
+
+ pr_debug("Freeing SPA for %x:%x:%x\n", link->domain, link->bus,
+ link->dev);
+
+ if (spa && spa->spa_mem) {
+ free_pages((unsigned long) spa->spa_mem, spa->spa_order);
+ kfree(spa);
+ link->spa = NULL;
+ }
+}
+
+static int alloc_link(struct pci_dev *dev, int PE_mask, struct link **out_link)
+{
+ struct link *link;
+ int rc;
+
+ link = kzalloc(sizeof(struct link), GFP_KERNEL);
+ if (!link)
+ return -ENOMEM;
+
+ kref_init(&link->ref);
+ link->domain = pci_domain_nr(dev->bus);
+ link->bus = dev->bus->number;
+ link->dev = PCI_SLOT(dev->devfn);
+ atomic_set(&link->irq_available, MAX_IRQ_PER_LINK);
+
+ rc = alloc_spa(dev, link);
+ if (rc)
+ goto err_free;
+
+ rc = setup_xsl_irq(dev, link);
+ if (rc)
+ goto err_spa;
+
+ /* platform specific hook */
+ rc = pnv_ocxl_spa_setup(dev, link->spa->spa_mem, PE_mask,
+ &link->platform_data);
+ if (rc)
+ goto err_xsl_irq;
+
+ *out_link = link;
+ return 0;
+
+err_xsl_irq:
+ release_xsl_irq(link);
+err_spa:
+ free_spa(link);
+err_free:
+ kfree(link);
+ return rc;
+}
+
+static void free_link(struct link *link)
+{
+ release_xsl_irq(link);
+ free_spa(link);
+ kfree(link);
+}
+
+int ocxl_link_setup(struct pci_dev *dev, int PE_mask, void **link_handle)
+{
+ int rc = 0;
+ struct link *link;
+
+ mutex_lock(&links_list_lock);
+ list_for_each_entry(link, &links_list, list) {
+ /* The functions of a device all share the same link */
+ if (link->domain == pci_domain_nr(dev->bus) &&
+ link->bus == dev->bus->number &&
+ link->dev == PCI_SLOT(dev->devfn)) {
+ kref_get(&link->ref);
+ *link_handle = link;
+ goto unlock;
+ }
+ }
+ rc = alloc_link(dev, PE_mask, &link);
+ if (rc)
+ goto unlock;
+
+ list_add(&link->list, &links_list);
+ *link_handle = link;
+unlock:
+ mutex_unlock(&links_list_lock);
+ return rc;
+}
+
+static void release_xsl(struct kref *ref)
+{
+ struct link *link = container_of(ref, struct link, ref);
+
+ list_del(&link->list);
+ /* call platform code before releasing data */
+ pnv_ocxl_spa_release(link->platform_data);
+ free_link(link);
+}
+
+void ocxl_link_release(struct pci_dev *dev, void *link_handle)
+{
+ struct link *link = (struct link *) link_handle;
+
+ mutex_lock(&links_list_lock);
+ kref_put(&link->ref, release_xsl);
+ mutex_unlock(&links_list_lock);
+}
+
+static u64 calculate_cfg_state(bool kernel)
+{
+ u64 state;
+
+ state = SPA_CFG_DR;
+ if (mfspr(SPRN_LPCR) & LPCR_TC)
+ state |= SPA_CFG_TC;
+ if (radix_enabled())
+ state |= SPA_CFG_XLAT_ror;
+ else
+ state |= SPA_CFG_XLAT_hpt;
+ state |= SPA_CFG_HV;
+ if (kernel) {
+ if (mfmsr() & MSR_SF)
+ state |= SPA_CFG_SF;
+ } else {
+ state |= SPA_CFG_PR;
+ if (!test_tsk_thread_flag(current, TIF_32BIT))
+ state |= SPA_CFG_SF;
+ }
+ return state;
+}
+
+int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr,
+ u64 amr, struct mm_struct *mm,
+ void (*xsl_err_cb)(void *data, u64 addr, u64 dsisr),
+ void *xsl_err_data)
+{
+ struct link *link = (struct link *) link_handle;
+ struct spa *spa = link->spa;
+ struct ocxl_process_element *pe;
+ int pe_handle, rc = 0;
+ struct pe_data *pe_data;
+
+ BUILD_BUG_ON(sizeof(struct ocxl_process_element) != 128);
+ if (pasid > SPA_PASID_MAX)
+ return -EINVAL;
+
+ mutex_lock(&spa->spa_lock);
+ pe_handle = pasid & SPA_PE_MASK;
+ pe = spa->spa_mem + pe_handle;
+
+ if (pe->software_state) {
+ rc = -EBUSY;
+ goto unlock;
+ }
+
+ pe_data = kmalloc(sizeof(*pe_data), GFP_KERNEL);
+ if (!pe_data) {
+ rc = -ENOMEM;
+ goto unlock;
+ }
+
+ pe_data->mm = mm;
+ pe_data->xsl_err_cb = xsl_err_cb;
+ pe_data->xsl_err_data = xsl_err_data;
+
+ memset(pe, 0, sizeof(struct ocxl_process_element));
+ pe->config_state = cpu_to_be64(calculate_cfg_state(pidr == 0));
+ pe->lpid = cpu_to_be32(mfspr(SPRN_LPID));
+ pe->pid = cpu_to_be32(pidr);
+ pe->tid = cpu_to_be32(tidr);
+ pe->amr = cpu_to_be64(amr);
+ pe->software_state = cpu_to_be32(SPA_PE_VALID);
+
+ mm_context_add_copro(mm);
+ /*
+ * Barrier is to make sure PE is visible in the SPA before it
+ * is used by the device. It also helps with the global TLBI
+ * invalidation
+ */
+ mb();
+ radix_tree_insert(&spa->pe_tree, pe_handle, pe_data);
+
+ /*
+ * The mm must stay valid for as long as the device uses it. We
+ * lower the count when the context is removed from the SPA.
+ *
+ * We grab mm_count (and not mm_users), as we don't want to
+ * end up in a circular dependency if a process mmaps its
+ * mmio, therefore incrementing the file ref count when
+ * calling mmap(), and forgets to unmap before exiting. In
+ * that scenario, when the kernel handles the death of the
+ * process, the file is not cleaned because unmap was not
+ * called, and the mm wouldn't be freed because we would still
+ * have a reference on mm_users. Incrementing mm_count solves
+ * the problem.
+ */
+ mmgrab(mm);
+unlock:
+ mutex_unlock(&spa->spa_lock);
+ return rc;
+}
+
+int ocxl_link_remove_pe(void *link_handle, int pasid)
+{
+ struct link *link = (struct link *) link_handle;
+ struct spa *spa = link->spa;
+ struct ocxl_process_element *pe;
+ struct pe_data *pe_data;
+ int pe_handle, rc;
+
+ if (pasid > SPA_PASID_MAX)
+ return -EINVAL;
+
+ /*
+ * About synchronization with our memory fault handler:
+ *
+ * Before removing the PE, the driver is supposed to have
+ * notified the AFU, which should have cleaned up and make
+ * sure the PASID is no longer in use, including pending
+ * interrupts. However, there's no way to be sure...
+ *
+ * We clear the PE and remove the context from our radix
+ * tree. From that point on, any new interrupt for that
+ * context will fail silently, which is ok. As mentioned
+ * above, that's not expected, but it could happen if the
+ * driver or AFU didn't do the right thing.
+ *
+ * There could still be a bottom half running, but we don't
+ * need to wait/flush, as it is managing a reference count on
+ * the mm it reads from the radix tree.
+ */
+ pe_handle = pasid & SPA_PE_MASK;
+ pe = spa->spa_mem + pe_handle;
+
+ mutex_lock(&spa->spa_lock);
+
+ if (!(be32_to_cpu(pe->software_state) & SPA_PE_VALID)) {
+ rc = -EINVAL;
+ goto unlock;
+ }
+
+ memset(pe, 0, sizeof(struct ocxl_process_element));
+ /*
+ * The barrier makes sure the PE is removed from the SPA
+ * before we clear the NPU context cache below, so that the
+ * old PE cannot be reloaded erroneously.
+ */
+ mb();
+
+ /*
+ * hook to platform code
+ * On powerpc, the entry needs to be cleared from the context
+ * cache of the NPU.
+ */
+ rc = pnv_ocxl_spa_remove_pe(link->platform_data, pe_handle);
+ WARN_ON(rc);
+
+ pe_data = radix_tree_delete(&spa->pe_tree, pe_handle);
+ if (!pe_data) {
+ WARN(1, "Couldn't find pe data when removing PE\n");
+ } else {
+ mm_context_remove_copro(pe_data->mm);
+ mmdrop(pe_data->mm);
+ kfree_rcu(pe_data, rcu);
+ }
+unlock:
+ mutex_unlock(&spa->spa_lock);
+ return rc;
+}