powerpc/eeh: EEH support for VFIO PCI device

The patch exports functions to be used by new VFIO ioctl command,
which will be introduced in subsequent patch, to support EEH
functinality for VFIO PCI devices.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Author: Gavin Shan

arch/powerpc/include/asm/eeh.h

@@ -172,6 +172,11 @@ enum {
 #define EEH_STATE_DMA_ACTIVE	(1 << 4)	/* Active DMA		*/
 #define EEH_STATE_MMIO_ENABLED	(1 << 5)	/* MMIO enabled		*/
 #define EEH_STATE_DMA_ENABLED	(1 << 6)	/* DMA enabled		*/
+#define EEH_PE_STATE_NORMAL		0	/* Normal state		*/
+#define EEH_PE_STATE_RESET		1	/* PE reset asserted	*/
+#define EEH_PE_STATE_STOPPED_IO_DMA	2	/* Frozen PE		*/
+#define EEH_PE_STATE_STOPPED_DMA	4	/* Stopped DMA, Enabled IO */
+#define EEH_PE_STATE_UNAVAIL		5	/* Unavailable		*/
 #define EEH_RESET_DEACTIVATE	0	/* Deactivate the PE reset	*/
 #define EEH_RESET_HOT		1	/* Hot reset			*/
 #define EEH_RESET_FUNDAMENTAL	3	/* Fundamental reset		*/
@@ -279,6 +284,13 @@ void eeh_add_device_late(struct pci_dev *);
 void eeh_add_device_tree_late(struct pci_bus *);
 void eeh_add_sysfs_files(struct pci_bus *);
 void eeh_remove_device(struct pci_dev *);
+int eeh_dev_open(struct pci_dev *pdev);
+void eeh_dev_release(struct pci_dev *pdev);
+struct eeh_pe *eeh_iommu_group_to_pe(struct iommu_group *group);
+int eeh_pe_set_option(struct eeh_pe *pe, int option);
+int eeh_pe_get_state(struct eeh_pe *pe);
+int eeh_pe_reset(struct eeh_pe *pe, int option);
+int eeh_pe_configure(struct eeh_pe *pe);
 
 /**
  * EEH_POSSIBLE_ERROR() -- test for possible MMIO failure.

arch/powerpc/kernel/eeh.c

@@ -40,6 +40,7 @@
 #include <asm/eeh.h>
 #include <asm/eeh_event.h>
 #include <asm/io.h>
+#include <asm/iommu.h>
 #include <asm/machdep.h>
 #include <asm/ppc-pci.h>
 #include <asm/rtas.h>
@@ -108,6 +109,9 @@ struct eeh_ops *eeh_ops = NULL;
 /* Lock to avoid races due to multiple reports of an error */
 DEFINE_RAW_SPINLOCK(confirm_error_lock);
 
+/* Lock to protect passed flags */
+static DEFINE_MUTEX(eeh_dev_mutex);
+
 /* Buffer for reporting pci register dumps. Its here in BSS, and
  * not dynamically alloced, so that it ends up in RMO where RTAS
  * can access it.
@@ -1108,6 +1112,270 @@ void eeh_remove_device(struct pci_dev *dev)
 	edev->mode &= ~EEH_DEV_SYSFS;
 }
 
+/**
+ * eeh_dev_open - Increase count of pass through devices for PE
+ * @pdev: PCI device
+ *
+ * Increase count of passed through devices for the indicated
+ * PE. In the result, the EEH errors detected on the PE won't be
+ * reported. The PE owner will be responsible for detection
+ * and recovery.
+ */
+int eeh_dev_open(struct pci_dev *pdev)
+{
+	struct eeh_dev *edev;
+
+	mutex_lock(&eeh_dev_mutex);
+
+	/* No PCI device ? */
+	if (!pdev)
+		goto out;
+
+	/* No EEH device or PE ? */
+	edev = pci_dev_to_eeh_dev(pdev);
+	if (!edev || !edev->pe)
+		goto out;
+
+	/* Increase PE's pass through count */
+	atomic_inc(&edev->pe->pass_dev_cnt);
+	mutex_unlock(&eeh_dev_mutex);
+
+	return 0;
+out:
+	mutex_unlock(&eeh_dev_mutex);
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(eeh_dev_open);
+
+/**
+ * eeh_dev_release - Decrease count of pass through devices for PE
+ * @pdev: PCI device
+ *
+ * Decrease count of pass through devices for the indicated PE. If
+ * there is no passed through device in PE, the EEH errors detected
+ * on the PE will be reported and handled as usual.
+ */
+void eeh_dev_release(struct pci_dev *pdev)
+{
+	struct eeh_dev *edev;
+
+	mutex_lock(&eeh_dev_mutex);
+
+	/* No PCI device ? */
+	if (!pdev)
+		goto out;
+
+	/* No EEH device ? */
+	edev = pci_dev_to_eeh_dev(pdev);
+	if (!edev || !edev->pe || !eeh_pe_passed(edev->pe))
+		goto out;
+
+	/* Decrease PE's pass through count */
+	atomic_dec(&edev->pe->pass_dev_cnt);
+	WARN_ON(atomic_read(&edev->pe->pass_dev_cnt) < 0);
+out:
+	mutex_unlock(&eeh_dev_mutex);
+}
+EXPORT_SYMBOL(eeh_dev_release);
+
+/**
+ * eeh_iommu_group_to_pe - Convert IOMMU group to EEH PE
+ * @group: IOMMU group
+ *
+ * The routine is called to convert IOMMU group to EEH PE.
+ */
+struct eeh_pe *eeh_iommu_group_to_pe(struct iommu_group *group)
+{
+	struct iommu_table *tbl;
+	struct pci_dev *pdev = NULL;
+	struct eeh_dev *edev;
+	bool found = false;
+
+	/* No IOMMU group ? */
+	if (!group)
+		return NULL;
+
+	/* No PCI device ? */
+	for_each_pci_dev(pdev) {
+		tbl = get_iommu_table_base(&pdev->dev);
+		if (tbl && tbl->it_group == group) {
+			found = true;
+			break;
+		}
+	}
+	if (!found)
+		return NULL;
+
+	/* No EEH device or PE ? */
+	edev = pci_dev_to_eeh_dev(pdev);
+	if (!edev || !edev->pe)
+		return NULL;
+
+	return edev->pe;
+}
+
+/**
+ * eeh_pe_set_option - Set options for the indicated PE
+ * @pe: EEH PE
+ * @option: requested option
+ *
+ * The routine is called to enable or disable EEH functionality
+ * on the indicated PE, to enable IO or DMA for the frozen PE.
+ */
+int eeh_pe_set_option(struct eeh_pe *pe, int option)
+{
+	int ret = 0;
+
+	/* Invalid PE ? */
+	if (!pe)
+		return -ENODEV;
+
+	/*
+	 * EEH functionality could possibly be disabled, just
+	 * return error for the case. And the EEH functinality
+	 * isn't expected to be disabled on one specific PE.
+	 */
+	switch (option) {
+	case EEH_OPT_ENABLE:
+		if (eeh_enabled())
+			break;
+		ret = -EIO;
+		break;
+	case EEH_OPT_DISABLE:
+		break;
+	case EEH_OPT_THAW_MMIO:
+	case EEH_OPT_THAW_DMA:
+		if (!eeh_ops || !eeh_ops->set_option) {
+			ret = -ENOENT;
+			break;
+		}
+
+		ret = eeh_ops->set_option(pe, option);
+		break;
+	default:
+		pr_debug("%s: Option %d out of range (%d, %d)\n",
+			__func__, option, EEH_OPT_DISABLE, EEH_OPT_THAW_DMA);
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(eeh_pe_set_option);
+
+/**
+ * eeh_pe_get_state - Retrieve PE's state
+ * @pe: EEH PE
+ *
+ * Retrieve the PE's state, which includes 3 aspects: enabled
+ * DMA, enabled IO and asserted reset.
+ */
+int eeh_pe_get_state(struct eeh_pe *pe)
+{
+	int result, ret = 0;
+	bool rst_active, dma_en, mmio_en;
+
+	/* Existing PE ? */
+	if (!pe)
+		return -ENODEV;
+
+	if (!eeh_ops || !eeh_ops->get_state)
+		return -ENOENT;
+
+	result = eeh_ops->get_state(pe, NULL);
+	rst_active = !!(result & EEH_STATE_RESET_ACTIVE);
+	dma_en = !!(result & EEH_STATE_DMA_ENABLED);
+	mmio_en = !!(result & EEH_STATE_MMIO_ENABLED);
+
+	if (rst_active)
+		ret = EEH_PE_STATE_RESET;
+	else if (dma_en && mmio_en)
+		ret = EEH_PE_STATE_NORMAL;
+	else if (!dma_en && !mmio_en)
+		ret = EEH_PE_STATE_STOPPED_IO_DMA;
+	else if (!dma_en && mmio_en)
+		ret = EEH_PE_STATE_STOPPED_DMA;
+	else
+		ret = EEH_PE_STATE_UNAVAIL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(eeh_pe_get_state);
+
+/**
+ * eeh_pe_reset - Issue PE reset according to specified type
+ * @pe: EEH PE
+ * @option: reset type
+ *
+ * The routine is called to reset the specified PE with the
+ * indicated type, either fundamental reset or hot reset.
+ * PE reset is the most important part for error recovery.
+ */
+int eeh_pe_reset(struct eeh_pe *pe, int option)
+{
+	int ret = 0;
+
+	/* Invalid PE ? */
+	if (!pe)
+		return -ENODEV;
+
+	if (!eeh_ops || !eeh_ops->set_option || !eeh_ops->reset)
+		return -ENOENT;
+
+	switch (option) {
+	case EEH_RESET_DEACTIVATE:
+		ret = eeh_ops->reset(pe, option);
+		if (ret)
+			break;
+
+		/*
+		 * The PE is still in frozen state and we need to clear
+		 * that. It's good to clear frozen state after deassert
+		 * to avoid messy IO access during reset, which might
+		 * cause recursive frozen PE.
+		 */
+		ret = eeh_ops->set_option(pe, EEH_OPT_THAW_MMIO);
+		if (!ret)
+			ret = eeh_ops->set_option(pe, EEH_OPT_THAW_DMA);
+		if (!ret)
+			eeh_pe_state_clear(pe, EEH_PE_ISOLATED);
+		break;
+	case EEH_RESET_HOT:
+	case EEH_RESET_FUNDAMENTAL:
+		ret = eeh_ops->reset(pe, option);
+		break;
+	default:
+		pr_debug("%s: Unsupported option %d\n",
+			__func__, option);
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(eeh_pe_reset);
+
+/**
+ * eeh_pe_configure - Configure PCI bridges after PE reset
+ * @pe: EEH PE
+ *
+ * The routine is called to restore the PCI config space for
+ * those PCI devices, especially PCI bridges affected by PE
+ * reset issued previously.
+ */
+int eeh_pe_configure(struct eeh_pe *pe)
+{
+	int ret = 0;
+
+	/* Invalid PE ? */
+	if (!pe)
+		return -ENODEV;
+
+	/* Restore config space for the affected devices */
+	eeh_pe_restore_bars(pe);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(eeh_pe_configure);
+
 static int proc_eeh_show(struct seq_file *m, void *v)
 {
 	if (!eeh_enabled()) {