Intel IOMMU Suspend/Resume Support - DMAR

This patch implements the suspend and resume feature for Intel IOMMU
DMAR. It hooks to kernel suspend and resume interface. When suspend happens, it
saves necessary hardware registers. When resume happens, it restores the
registers and restarts IOMMU by enabling translation, setting up root entry, and
re-enabling queued invalidation.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 157 insertions, 0 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 23e56a564e05..ef5795d0396b 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -36,6 +36,7 @@
 #include <linux/iova.h>
 #include <linux/iommu.h>
 #include <linux/intel-iommu.h>
+#include <linux/sysdev.h>
 #include <asm/cacheflush.h>
 #include <asm/iommu.h>
 #include "pci.h"
@@ -2597,6 +2598,150 @@ static void __init init_no_remapping_devices(void)
         }
 }
 
+#ifdef CONFIG_SUSPEND
+static int init_iommu_hw(void)
+{
+        struct dmar_drhd_unit *drhd;
+        struct intel_iommu *iommu = NULL;
+
+        for_each_active_iommu(iommu, drhd)
+                if (iommu->qi)
+                        dmar_reenable_qi(iommu);
+
+        for_each_active_iommu(iommu, drhd) {
+                iommu_flush_write_buffer(iommu);
+
+                iommu_set_root_entry(iommu);
+
+                iommu->flush.flush_context(iommu, 0, 0, 0,
+                                                DMA_CCMD_GLOBAL_INVL, 0);
+                iommu->flush.flush_iotlb(iommu, 0, 0, 0,
+                                                DMA_TLB_GLOBAL_FLUSH, 0);
+                iommu_disable_protect_mem_regions(iommu);
+                iommu_enable_translation(iommu);
+        }
+
+        return 0;
+}
+
+static void iommu_flush_all(void)
+{
+        struct dmar_drhd_unit *drhd;
+        struct intel_iommu *iommu;
+
+        for_each_active_iommu(iommu, drhd) {
+                iommu->flush.flush_context(iommu, 0, 0, 0,
+                                                DMA_CCMD_GLOBAL_INVL, 0);
+                iommu->flush.flush_iotlb(iommu, 0, 0, 0,
+                                                DMA_TLB_GLOBAL_FLUSH, 0);
+        }
+}
+
+static int iommu_suspend(struct sys_device *dev, pm_message_t state)
+{
+        struct dmar_drhd_unit *drhd;
+        struct intel_iommu *iommu = NULL;
+        unsigned long flag;
+
+        for_each_active_iommu(iommu, drhd) {
+                iommu->iommu_state = kzalloc(sizeof(u32) * MAX_SR_DMAR_REGS,
+                                                 GFP_ATOMIC);
+                if (!iommu->iommu_state)
+                        goto nomem;
+        }
+
+        iommu_flush_all();
+
+        for_each_active_iommu(iommu, drhd) {
+                iommu_disable_translation(iommu);
+
+                spin_lock_irqsave(&iommu->register_lock, flag);
+
+                iommu->iommu_state[SR_DMAR_FECTL_REG] =
+                        readl(iommu->reg + DMAR_FECTL_REG);
+                iommu->iommu_state[SR_DMAR_FEDATA_REG] =
+                        readl(iommu->reg + DMAR_FEDATA_REG);
+                iommu->iommu_state[SR_DMAR_FEADDR_REG] =
+                        readl(iommu->reg + DMAR_FEADDR_REG);
+                iommu->iommu_state[SR_DMAR_FEUADDR_REG] =
+                        readl(iommu->reg + DMAR_FEUADDR_REG);
+
+                spin_unlock_irqrestore(&iommu->register_lock, flag);
+        }
+        return 0;
+
+nomem:
+        for_each_active_iommu(iommu, drhd)
+                kfree(iommu->iommu_state);
+
+        return -ENOMEM;
+}
+
+static int iommu_resume(struct sys_device *dev)
+{
+        struct dmar_drhd_unit *drhd;
+        struct intel_iommu *iommu = NULL;
+        unsigned long flag;
+
+        if (init_iommu_hw()) {
+                WARN(1, "IOMMU setup failed, DMAR can not resume!\n");
+                return -EIO;
+        }
+
+        for_each_active_iommu(iommu, drhd) {
+
+                spin_lock_irqsave(&iommu->register_lock, flag);
+
+                writel(iommu->iommu_state[SR_DMAR_FECTL_REG],
+                        iommu->reg + DMAR_FECTL_REG);
+                writel(iommu->iommu_state[SR_DMAR_FEDATA_REG],
+                        iommu->reg + DMAR_FEDATA_REG);
+                writel(iommu->iommu_state[SR_DMAR_FEADDR_REG],
+                        iommu->reg + DMAR_FEADDR_REG);
+                writel(iommu->iommu_state[SR_DMAR_FEUADDR_REG],
+                        iommu->reg + DMAR_FEUADDR_REG);
+
+                spin_unlock_irqrestore(&iommu->register_lock, flag);
+        }
+
+        for_each_active_iommu(iommu, drhd)
+                kfree(iommu->iommu_state);
+
+        return 0;
+}
+
+static struct sysdev_class iommu_sysclass = {
+        .name           = "iommu",
+        .resume         = iommu_resume,
+        .suspend        = iommu_suspend,
+};
+
+static struct sys_device device_iommu = {
+        .cls    = &iommu_sysclass,
+};
+
+static int __init init_iommu_sysfs(void)
+{
+        int error;
+
+        error = sysdev_class_register(&iommu_sysclass);
+        if (error)
+                return error;
+
+        error = sysdev_register(&device_iommu);
+        if (error)
+                sysdev_class_unregister(&iommu_sysclass);
+
+        return error;
+}
+
+#else
+static int __init init_iommu_sysfs(void)
+{
+        return 0;
+}
+#endif  /* CONFIG_PM */
+
 int __init intel_iommu_init(void)
 {
         int ret = 0;
@@ -2632,6 +2777,7 @@ int __init intel_iommu_init(void)
         init_timer(&unmap_timer);
         force_iommu = 1;
         dma_ops = &intel_dma_ops;
+        init_iommu_sysfs();
 
         register_iommu(&intel_iommu_ops);
 
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 77214ead1a36..3771cd1f876e 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -284,6 +284,14 @@ struct iommu_flush {
                 unsigned int size_order, u64 type, int non_present_entry_flush);
 };
 
+enum {
+        SR_DMAR_FECTL_REG,
+        SR_DMAR_FEDATA_REG,
+        SR_DMAR_FEADDR_REG,
+        SR_DMAR_FEUADDR_REG,
+        MAX_SR_DMAR_REGS
+};
+
 struct intel_iommu {
         void __iomem    *reg; /* Pointer to hardware regs, virtual addr */
         u64             cap;
@@ -304,6 +312,8 @@ struct intel_iommu {
         struct iommu_flush flush;
 #endif
         struct q_inval  *qi;            /* Queued invalidation info */
+        u32 *iommu_state; /* Store iommu states between suspend and resume.*/
+
 #ifdef CONFIG_INTR_REMAP
         struct ir_table *ir_table;      /* Interrupt remapping info */
 #endif
@@ -322,6 +332,7 @@ extern int alloc_iommu(struct dmar_drhd_unit *drhd);
 extern void free_iommu(struct intel_iommu *iommu);
 extern int dmar_enable_qi(struct intel_iommu *iommu);
 extern void dmar_disable_qi(struct intel_iommu *iommu);
+extern int dmar_reenable_qi(struct intel_iommu *iommu);
 extern void qi_global_iec(struct intel_iommu *iommu);
 
 extern int qi_flush_context(struct intel_iommu *iommu, u16 did, u16 sid,