From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

Store and restore active context and micro-TLB registers.

Tested on R-Car H3 Starter Kit.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Signed-off-by: Mykola Kvach <mykola_kvach@epam.com>
---
Changes in V7:
- moved suspend context allocation before pci stuff
---
 xen/drivers/passthrough/arm/ipmmu-vmsa.c | 305 ++++++++++++++++++++++-
 1 file changed, 298 insertions(+), 7 deletions(-)

diff --git a/xen/drivers/passthrough/arm/ipmmu-vmsa.c b/xen/drivers/passthrough/arm/ipmmu-vmsa.c
index ea9fa9ddf3..6765bd3083 100644
--- a/xen/drivers/passthrough/arm/ipmmu-vmsa.c
+++ b/xen/drivers/passthrough/arm/ipmmu-vmsa.c
@@ -71,6 +71,8 @@
 })
 #endif
 
+#define dev_dbg(dev, fmt, ...)    \
+    dev_print(dev, XENLOG_DEBUG, fmt, ## __VA_ARGS__)
 #define dev_info(dev, fmt, ...)    \
     dev_print(dev, XENLOG_INFO, fmt, ## __VA_ARGS__)
 #define dev_warn(dev, fmt, ...)    \
@@ -130,6 +132,24 @@ struct ipmmu_features {
     unsigned int imuctr_ttsel_mask;
 };
 
+#ifdef CONFIG_SYSTEM_SUSPEND
+
+struct ipmmu_reg_ctx {
+    unsigned int imttlbr0;
+    unsigned int imttubr0;
+    unsigned int imttbcr;
+    unsigned int imctr;
+};
+
+struct ipmmu_vmsa_backup {
+    struct device *dev;
+    unsigned int *utlbs_val;
+    unsigned int *asids_val;
+    struct list_head list;
+};
+
+#endif
+
 /* Root/Cache IPMMU device's information */
 struct ipmmu_vmsa_device {
     struct device *dev;
@@ -142,6 +162,9 @@ struct ipmmu_vmsa_device {
     struct ipmmu_vmsa_domain *domains[IPMMU_CTX_MAX];
     unsigned int utlb_refcount[IPMMU_UTLB_MAX];
     const struct ipmmu_features *features;
+#ifdef CONFIG_SYSTEM_SUSPEND
+    struct ipmmu_reg_ctx *reg_backup[IPMMU_CTX_MAX];
+#endif
 };
 
 /*
@@ -547,6 +570,245 @@ static void ipmmu_domain_free_context(struct ipmmu_vmsa_device *mmu,
     spin_unlock_irqrestore(&mmu->lock, flags);
 }
 
+#ifdef CONFIG_SYSTEM_SUSPEND
+
+static DEFINE_SPINLOCK(ipmmu_devices_backup_lock);
+static LIST_HEAD(ipmmu_devices_backup);
+
+static struct ipmmu_reg_ctx root_pgtable[IPMMU_CTX_MAX];
+
+static uint32_t ipmmu_imuasid_read(struct ipmmu_vmsa_device *mmu,
+                                   unsigned int utlb)
+{
+    return ipmmu_read(mmu, ipmmu_utlb_reg(mmu, IMUASID(utlb)));
+}
+
+static void ipmmu_utlbs_backup(struct ipmmu_vmsa_device *mmu)
+{
+    struct ipmmu_vmsa_backup *backup_data;
+
+    dev_dbg(mmu->dev, "Handle micro-TLBs backup\n");
+
+    spin_lock(&ipmmu_devices_backup_lock);
+
+    list_for_each_entry( backup_data, &ipmmu_devices_backup, list )
+    {
+        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(backup_data->dev);
+        unsigned int i;
+
+        if ( to_ipmmu(backup_data->dev) != mmu )
+            continue;
+
+        for ( i = 0; i < fwspec->num_ids; i++ )
+        {
+            unsigned int utlb = fwspec->ids[i];
+
+            backup_data->asids_val[i] = ipmmu_imuasid_read(mmu, utlb);
+            backup_data->utlbs_val[i] = ipmmu_imuctr_read(mmu, utlb);
+        }
+    }
+
+    spin_unlock(&ipmmu_devices_backup_lock);
+}
+
+static void ipmmu_utlbs_restore(struct ipmmu_vmsa_device *mmu)
+{
+    struct ipmmu_vmsa_backup *backup_data;
+
+    dev_dbg(mmu->dev, "Handle micro-TLBs restore\n");
+
+    spin_lock(&ipmmu_devices_backup_lock);
+
+    list_for_each_entry( backup_data, &ipmmu_devices_backup, list )
+    {
+        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(backup_data->dev);
+        unsigned int i;
+
+        if ( to_ipmmu(backup_data->dev) != mmu )
+            continue;
+
+        for ( i = 0; i < fwspec->num_ids; i++ )
+        {
+            unsigned int utlb = fwspec->ids[i];
+
+            ipmmu_imuasid_write(mmu, utlb, backup_data->asids_val[i]);
+            ipmmu_imuctr_write(mmu, utlb, backup_data->utlbs_val[i]);
+        }
+    }
+
+    spin_unlock(&ipmmu_devices_backup_lock);
+}
+
+static void ipmmu_domain_backup_context(struct ipmmu_vmsa_domain *domain)
+{
+    struct ipmmu_vmsa_device *mmu = domain->mmu->root;
+    struct ipmmu_reg_ctx *regs = mmu->reg_backup[domain->context_id];
+
+    dev_dbg(mmu->dev, "Handle domain context %u backup\n", domain->context_id);
+
+    regs->imttlbr0 = ipmmu_ctx_read_root(domain, IMTTLBR0);
+    regs->imttubr0 = ipmmu_ctx_read_root(domain, IMTTUBR0);
+    regs->imttbcr  = ipmmu_ctx_read_root(domain, IMTTBCR);
+    regs->imctr    = ipmmu_ctx_read_root(domain, IMCTR);
+}
+
+static void ipmmu_domain_restore_context(struct ipmmu_vmsa_domain *domain)
+{
+    struct ipmmu_vmsa_device *mmu = domain->mmu->root;
+    struct ipmmu_reg_ctx *regs  = mmu->reg_backup[domain->context_id];
+
+    dev_dbg(mmu->dev, "Handle domain context %u restore\n", domain->context_id);
+
+    ipmmu_ctx_write_root(domain, IMTTLBR0, regs->imttlbr0);
+    ipmmu_ctx_write_root(domain, IMTTUBR0, regs->imttubr0);
+    ipmmu_ctx_write_root(domain, IMTTBCR,  regs->imttbcr);
+    ipmmu_ctx_write_all(domain,  IMCTR,    regs->imctr | IMCTR_FLUSH);
+}
+
+/*
+ * Xen: Unlike Linux implementation, Xen uses a single driver instance
+ * for handling all IPMMUs. There is no framework for ipmmu_suspend/resume
+ * callbacks to be invoked for each IPMMU device. So, we need to iterate
+ * through all registered IPMMUs performing required actions.
+ *
+ * Also take care of restoring special settings, such as translation
+ * table format, etc.
+ */
+static int __must_check ipmmu_suspend(void)
+{
+    struct ipmmu_vmsa_device *mmu;
+
+    if ( !iommu_enabled )
+        return 0;
+
+    printk(XENLOG_DEBUG "ipmmu: Suspending...\n");
+
+    spin_lock(&ipmmu_devices_lock);
+
+    list_for_each_entry( mmu, &ipmmu_devices, list )
+    {
+        if ( ipmmu_is_root(mmu) )
+        {
+            unsigned int i;
+
+            for ( i = 0; i < mmu->num_ctx; i++ )
+            {
+                if ( !mmu->domains[i] )
+                    continue;
+                ipmmu_domain_backup_context(mmu->domains[i]);
+            }
+        }
+        else
+            ipmmu_utlbs_backup(mmu);
+    }
+
+    spin_unlock(&ipmmu_devices_lock);
+
+    return 0;
+}
+
+static void ipmmu_resume(void)
+{
+    struct ipmmu_vmsa_device *mmu;
+
+    if ( !iommu_enabled )
+        return;
+
+    printk(XENLOG_DEBUG "ipmmu: Resuming...\n");
+
+    spin_lock(&ipmmu_devices_lock);
+
+    list_for_each_entry( mmu, &ipmmu_devices, list )
+    {
+        uint32_t reg;
+
+        /* Do not use security group function */
+        reg = IMSCTLR + mmu->features->control_offset_base;
+        ipmmu_write(mmu, reg, ipmmu_read(mmu, reg) & ~IMSCTLR_USE_SECGRP);
+
+        if ( ipmmu_is_root(mmu) )
+        {
+            unsigned int i;
+
+            /* Use stage 2 translation table format */
+            reg = IMSAUXCTLR + mmu->features->control_offset_base;
+            ipmmu_write(mmu, reg, ipmmu_read(mmu, reg) | IMSAUXCTLR_S2PTE);
+
+            for ( i = 0; i < mmu->num_ctx; i++ )
+            {
+                if ( !mmu->domains[i] )
+                    continue;
+                ipmmu_domain_restore_context(mmu->domains[i]);
+            }
+        }
+        else
+            ipmmu_utlbs_restore(mmu);
+    }
+
+    spin_unlock(&ipmmu_devices_lock);
+}
+
+static int ipmmu_alloc_ctx_suspend(struct device *dev)
+{
+    struct ipmmu_vmsa_backup *backup_data;
+    unsigned int *utlbs_val, *asids_val;
+    struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+
+    utlbs_val = xzalloc_array(unsigned int, fwspec->num_ids);
+    if ( !utlbs_val )
+        return -ENOMEM;
+
+    asids_val = xzalloc_array(unsigned int, fwspec->num_ids);
+    if ( !asids_val )
+    {
+        xfree(utlbs_val);
+        return -ENOMEM;
+    }
+
+    backup_data = xzalloc(struct ipmmu_vmsa_backup);
+    if ( !backup_data )
+    {
+        xfree(utlbs_val);
+        xfree(asids_val);
+        return -ENOMEM;
+    }
+
+    backup_data->dev = dev;
+    backup_data->utlbs_val = utlbs_val;
+    backup_data->asids_val = asids_val;
+
+    spin_lock(&ipmmu_devices_backup_lock);
+    list_add(&backup_data->list, &ipmmu_devices_backup);
+    spin_unlock(&ipmmu_devices_backup_lock);
+
+    return 0;
+}
+
+#ifdef CONFIG_HAS_PCI
+static void ipmmu_free_ctx_suspend(struct device *dev)
+{
+    struct ipmmu_vmsa_backup *backup_data, *tmp;
+
+    spin_lock(&ipmmu_devices_backup_lock);
+
+    list_for_each_entry_safe( backup_data, tmp, &ipmmu_devices_backup, list )
+    {
+        if ( backup_data->dev == dev )
+        {
+            list_del(&backup_data->list);
+            xfree(backup_data->utlbs_val);
+            xfree(backup_data->asids_val);
+            xfree(backup_data);
+            break;
+        }
+    }
+
+    spin_unlock(&ipmmu_devices_backup_lock);
+}
+#endif /* CONFIG_HAS_PCI */
+
+#endif /* CONFIG_SYSTEM_SUSPEND */
+
 static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)
 {
     uint64_t ttbr;
@@ -559,6 +821,9 @@ static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)
         return ret;
 
     domain->context_id = ret;
+#ifdef CONFIG_SYSTEM_SUSPEND
+    domain->mmu->root->reg_backup[ret] = &root_pgtable[ret];
+#endif
 
     /*
      * TTBR0
@@ -615,6 +880,9 @@ static void ipmmu_domain_destroy_context(struct ipmmu_vmsa_domain *domain)
     ipmmu_ctx_write_root(domain, IMCTR, IMCTR_FLUSH);
     ipmmu_tlb_sync(domain);
 
+#ifdef CONFIG_SYSTEM_SUSPEND
+    domain->mmu->root->reg_backup[domain->context_id] = NULL;
+#endif
     ipmmu_domain_free_context(domain->mmu->root, domain->context_id);
 }
 
@@ -1340,10 +1608,11 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
     struct iommu_fwspec *fwspec;
 
 #ifdef CONFIG_HAS_PCI
+    int ret;
+
     if ( dev_is_pci(dev) )
     {
         struct pci_dev *pdev = dev_to_pci(dev);
-        int ret;
 
         if ( devfn != pdev->devfn )
             return 0;
@@ -1371,6 +1640,15 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
         /* Let Xen know that the master device is protected by an IOMMU. */
         dt_device_set_protected(dev_to_dt(dev));
     }
+
+#ifdef CONFIG_SYSTEM_SUSPEND
+    if ( ipmmu_alloc_ctx_suspend(dev) )
+    {
+        dev_err(dev, "Failed to allocate context for suspend\n");
+        return -ENOMEM;
+    }
+#endif
+
 #ifdef CONFIG_HAS_PCI
     if ( dev_is_pci(dev) )
     {
@@ -1379,26 +1657,28 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
         struct pci_host_bridge *bridge;
         struct iommu_fwspec *fwspec_bridge;
         unsigned int utlb_osid0 = 0;
-        int ret;
 
         bridge = pci_find_host_bridge(pdev->seg, pdev->bus);
         if ( !bridge )
         {
             dev_err(dev, "Failed to find host bridge\n");
-            return -ENODEV;
+            ret = -ENODEV;
+            goto free_suspend_ctx;
         }
 
         fwspec_bridge = dev_iommu_fwspec_get(dt_to_dev(bridge->dt_node));
         if ( fwspec_bridge->num_ids < 1 )
         {
             dev_err(dev, "Failed to find host bridge uTLB\n");
-            return -ENXIO;
+            ret = -ENXIO;
+            goto free_suspend_ctx;
         }
 
         if ( fwspec->num_ids < 1 )
         {
             dev_err(dev, "Failed to find uTLB");
-            return -ENXIO;
+            ret = -ENXIO;
+            goto free_suspend_ctx;
         }
 
         rcar4_pcie_osid_regs_init(bridge);
@@ -1407,7 +1687,7 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
         if ( ret < 0 )
         {
             dev_err(dev, "No unused OSID regs\n");
-            return ret;
+            goto free_suspend_ctx;
         }
         reg_id = ret;
 
@@ -1422,7 +1702,7 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
         {
             rcar4_pcie_osid_bdf_clear(bridge, reg_id);
             rcar4_pcie_osid_reg_free(bridge, reg_id);
-            return ret;
+            goto free_suspend_ctx;
         }
     }
 #endif
@@ -1431,6 +1711,13 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
              dev_name(fwspec->iommu_dev), fwspec->num_ids);
 
     return 0;
+#ifdef CONFIG_HAS_PCI
+ free_suspend_ctx:
+#ifdef CONFIG_SYSTEM_SUSPEND
+    ipmmu_free_ctx_suspend(dev);
+#endif
+    return ret;
+#endif
 }
 
 static int ipmmu_iommu_domain_init(struct domain *d)
@@ -1492,6 +1779,10 @@ static const struct iommu_ops ipmmu_iommu_ops =
     .unmap_page      = arm_iommu_unmap_page,
     .dt_xlate        = ipmmu_dt_xlate,
     .add_device      = ipmmu_add_device,
+#ifdef CONFIG_SYSTEM_SUSPEND
+    .suspend         = ipmmu_suspend,
+    .resume          = ipmmu_resume,
+#endif
 };
 
 static __init int ipmmu_init(struct dt_device_node *node, const void *data)
-- 
2.43.0

On 11.12.25 20:43, Mykola Kvach wrote:

Hello Mykola


> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> Store and restore active context and micro-TLB registers.
> 
> Tested on R-Car H3 Starter Kit.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> Signed-off-by: Mykola Kvach <mykola_kvach@epam.com>
> ---
> Changes in V7:
> - moved suspend context allocation before pci stuff

  Thanks for making this change, one note below ...

> ---
>   xen/drivers/passthrough/arm/ipmmu-vmsa.c | 305 ++++++++++++++++++++++-
>   1 file changed, 298 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/arm/ipmmu-vmsa.c b/xen/drivers/passthrough/arm/ipmmu-vmsa.c
> index ea9fa9ddf3..6765bd3083 100644
> --- a/xen/drivers/passthrough/arm/ipmmu-vmsa.c
> +++ b/xen/drivers/passthrough/arm/ipmmu-vmsa.c
> @@ -71,6 +71,8 @@
>   })
>   #endif
>   
> +#define dev_dbg(dev, fmt, ...)    \
> +    dev_print(dev, XENLOG_DEBUG, fmt, ## __VA_ARGS__)
>   #define dev_info(dev, fmt, ...)    \
>       dev_print(dev, XENLOG_INFO, fmt, ## __VA_ARGS__)
>   #define dev_warn(dev, fmt, ...)    \
> @@ -130,6 +132,24 @@ struct ipmmu_features {
>       unsigned int imuctr_ttsel_mask;
>   };
>   
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +
> +struct ipmmu_reg_ctx {
> +    unsigned int imttlbr0;
> +    unsigned int imttubr0;
> +    unsigned int imttbcr;
> +    unsigned int imctr;
> +};
> +
> +struct ipmmu_vmsa_backup {
> +    struct device *dev;
> +    unsigned int *utlbs_val;
> +    unsigned int *asids_val;
> +    struct list_head list;
> +};
> +
> +#endif
> +
>   /* Root/Cache IPMMU device's information */
>   struct ipmmu_vmsa_device {
>       struct device *dev;
> @@ -142,6 +162,9 @@ struct ipmmu_vmsa_device {
>       struct ipmmu_vmsa_domain *domains[IPMMU_CTX_MAX];
>       unsigned int utlb_refcount[IPMMU_UTLB_MAX];
>       const struct ipmmu_features *features;
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +    struct ipmmu_reg_ctx *reg_backup[IPMMU_CTX_MAX];
> +#endif
>   };
>   
>   /*
> @@ -547,6 +570,245 @@ static void ipmmu_domain_free_context(struct ipmmu_vmsa_device *mmu,
>       spin_unlock_irqrestore(&mmu->lock, flags);
>   }
>   
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +
> +static DEFINE_SPINLOCK(ipmmu_devices_backup_lock);
> +static LIST_HEAD(ipmmu_devices_backup);
> +
> +static struct ipmmu_reg_ctx root_pgtable[IPMMU_CTX_MAX];
> +
> +static uint32_t ipmmu_imuasid_read(struct ipmmu_vmsa_device *mmu,
> +                                   unsigned int utlb)
> +{
> +    return ipmmu_read(mmu, ipmmu_utlb_reg(mmu, IMUASID(utlb)));
> +}
> +
> +static void ipmmu_utlbs_backup(struct ipmmu_vmsa_device *mmu)
> +{
> +    struct ipmmu_vmsa_backup *backup_data;
> +
> +    dev_dbg(mmu->dev, "Handle micro-TLBs backup\n");
> +
> +    spin_lock(&ipmmu_devices_backup_lock);
> +
> +    list_for_each_entry( backup_data, &ipmmu_devices_backup, list )
> +    {
> +        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(backup_data->dev);
> +        unsigned int i;
> +
> +        if ( to_ipmmu(backup_data->dev) != mmu )
> +            continue;
> +
> +        for ( i = 0; i < fwspec->num_ids; i++ )
> +        {
> +            unsigned int utlb = fwspec->ids[i];
> +
> +            backup_data->asids_val[i] = ipmmu_imuasid_read(mmu, utlb);
> +            backup_data->utlbs_val[i] = ipmmu_imuctr_read(mmu, utlb);
> +        }
> +    }
> +
> +    spin_unlock(&ipmmu_devices_backup_lock);
> +}
> +
> +static void ipmmu_utlbs_restore(struct ipmmu_vmsa_device *mmu)
> +{
> +    struct ipmmu_vmsa_backup *backup_data;
> +
> +    dev_dbg(mmu->dev, "Handle micro-TLBs restore\n");
> +
> +    spin_lock(&ipmmu_devices_backup_lock);
> +
> +    list_for_each_entry( backup_data, &ipmmu_devices_backup, list )
> +    {
> +        struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(backup_data->dev);
> +        unsigned int i;
> +
> +        if ( to_ipmmu(backup_data->dev) != mmu )
> +            continue;
> +
> +        for ( i = 0; i < fwspec->num_ids; i++ )
> +        {
> +            unsigned int utlb = fwspec->ids[i];
> +
> +            ipmmu_imuasid_write(mmu, utlb, backup_data->asids_val[i]);
> +            ipmmu_imuctr_write(mmu, utlb, backup_data->utlbs_val[i]);
> +        }
> +    }
> +
> +    spin_unlock(&ipmmu_devices_backup_lock);
> +}
> +
> +static void ipmmu_domain_backup_context(struct ipmmu_vmsa_domain *domain)
> +{
> +    struct ipmmu_vmsa_device *mmu = domain->mmu->root;
> +    struct ipmmu_reg_ctx *regs = mmu->reg_backup[domain->context_id];
> +
> +    dev_dbg(mmu->dev, "Handle domain context %u backup\n", domain->context_id);
> +
> +    regs->imttlbr0 = ipmmu_ctx_read_root(domain, IMTTLBR0);
> +    regs->imttubr0 = ipmmu_ctx_read_root(domain, IMTTUBR0);
> +    regs->imttbcr  = ipmmu_ctx_read_root(domain, IMTTBCR);
> +    regs->imctr    = ipmmu_ctx_read_root(domain, IMCTR);
> +}
> +
> +static void ipmmu_domain_restore_context(struct ipmmu_vmsa_domain *domain)
> +{
> +    struct ipmmu_vmsa_device *mmu = domain->mmu->root;
> +    struct ipmmu_reg_ctx *regs  = mmu->reg_backup[domain->context_id];
> +
> +    dev_dbg(mmu->dev, "Handle domain context %u restore\n", domain->context_id);
> +
> +    ipmmu_ctx_write_root(domain, IMTTLBR0, regs->imttlbr0);
> +    ipmmu_ctx_write_root(domain, IMTTUBR0, regs->imttubr0);
> +    ipmmu_ctx_write_root(domain, IMTTBCR,  regs->imttbcr);
> +    ipmmu_ctx_write_all(domain,  IMCTR,    regs->imctr | IMCTR_FLUSH);
> +}
> +
> +/*
> + * Xen: Unlike Linux implementation, Xen uses a single driver instance
> + * for handling all IPMMUs. There is no framework for ipmmu_suspend/resume
> + * callbacks to be invoked for each IPMMU device. So, we need to iterate
> + * through all registered IPMMUs performing required actions.
> + *
> + * Also take care of restoring special settings, such as translation
> + * table format, etc.
> + */
> +static int __must_check ipmmu_suspend(void)
> +{
> +    struct ipmmu_vmsa_device *mmu;
> +
> +    if ( !iommu_enabled )
> +        return 0;
> +
> +    printk(XENLOG_DEBUG "ipmmu: Suspending...\n");
> +
> +    spin_lock(&ipmmu_devices_lock);
> +
> +    list_for_each_entry( mmu, &ipmmu_devices, list )
> +    {
> +        if ( ipmmu_is_root(mmu) )
> +        {
> +            unsigned int i;
> +
> +            for ( i = 0; i < mmu->num_ctx; i++ )
> +            {
> +                if ( !mmu->domains[i] )
> +                    continue;
> +                ipmmu_domain_backup_context(mmu->domains[i]);
> +            }
> +        }
> +        else
> +            ipmmu_utlbs_backup(mmu);
> +    }
> +
> +    spin_unlock(&ipmmu_devices_lock);
> +
> +    return 0;
> +}
> +
> +static void ipmmu_resume(void)
> +{
> +    struct ipmmu_vmsa_device *mmu;
> +
> +    if ( !iommu_enabled )
> +        return;
> +
> +    printk(XENLOG_DEBUG "ipmmu: Resuming...\n");
> +
> +    spin_lock(&ipmmu_devices_lock);
> +
> +    list_for_each_entry( mmu, &ipmmu_devices, list )
> +    {
> +        uint32_t reg;
> +
> +        /* Do not use security group function */
> +        reg = IMSCTLR + mmu->features->control_offset_base;
> +        ipmmu_write(mmu, reg, ipmmu_read(mmu, reg) & ~IMSCTLR_USE_SECGRP);
> +
> +        if ( ipmmu_is_root(mmu) )
> +        {
> +            unsigned int i;
> +
> +            /* Use stage 2 translation table format */
> +            reg = IMSAUXCTLR + mmu->features->control_offset_base;
> +            ipmmu_write(mmu, reg, ipmmu_read(mmu, reg) | IMSAUXCTLR_S2PTE);
> +
> +            for ( i = 0; i < mmu->num_ctx; i++ )
> +            {
> +                if ( !mmu->domains[i] )
> +                    continue;
> +                ipmmu_domain_restore_context(mmu->domains[i]);
> +            }
> +        }
> +        else
> +            ipmmu_utlbs_restore(mmu);
> +    }
> +
> +    spin_unlock(&ipmmu_devices_lock);
> +}
> +
> +static int ipmmu_alloc_ctx_suspend(struct device *dev)
> +{
> +    struct ipmmu_vmsa_backup *backup_data;
> +    unsigned int *utlbs_val, *asids_val;
> +    struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> +
> +    utlbs_val = xzalloc_array(unsigned int, fwspec->num_ids);
> +    if ( !utlbs_val )
> +        return -ENOMEM;
> +
> +    asids_val = xzalloc_array(unsigned int, fwspec->num_ids);
> +    if ( !asids_val )
> +    {
> +        xfree(utlbs_val);
> +        return -ENOMEM;
> +    }
> +
> +    backup_data = xzalloc(struct ipmmu_vmsa_backup);
> +    if ( !backup_data )
> +    {
> +        xfree(utlbs_val);
> +        xfree(asids_val);
> +        return -ENOMEM;
> +    }
> +
> +    backup_data->dev = dev;
> +    backup_data->utlbs_val = utlbs_val;
> +    backup_data->asids_val = asids_val;
> +
> +    spin_lock(&ipmmu_devices_backup_lock);
> +    list_add(&backup_data->list, &ipmmu_devices_backup);
> +    spin_unlock(&ipmmu_devices_backup_lock);
> +
> +    return 0;
> +}
> +
> +#ifdef CONFIG_HAS_PCI
> +static void ipmmu_free_ctx_suspend(struct device *dev)
> +{
> +    struct ipmmu_vmsa_backup *backup_data, *tmp;
> +
> +    spin_lock(&ipmmu_devices_backup_lock);
> +
> +    list_for_each_entry_safe( backup_data, tmp, &ipmmu_devices_backup, list )
> +    {
> +        if ( backup_data->dev == dev )
> +        {
> +            list_del(&backup_data->list);
> +            xfree(backup_data->utlbs_val);
> +            xfree(backup_data->asids_val);
> +            xfree(backup_data);
> +            break;
> +        }
> +    }
> +
> +    spin_unlock(&ipmmu_devices_backup_lock);
> +}
> +#endif /* CONFIG_HAS_PCI */
> +
> +#endif /* CONFIG_SYSTEM_SUSPEND */


  ... I noticed the Kconfig guards for ipmmu_alloc_ctx_suspend() and 
ipmmu_free_ctx_suspend() are asymmetrical. This creates a configuration 
(CONFIG_SYSTEM_SUSPEND=y, CONFIG_HAS_PCI=n) where the allocation 
function exists but the deallocation function is compiled out.

While this feels a bit fragile, I understand this is necessary to avoid 
an "unused function" compiler error, as the only caller is within a 
CONFIG_HAS_PCI block. Since the alternative would break the build, I 
think the current implementation is acceptable. I have no further 
comments. The patch looks good now.


> +
>   static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)
>   {
>       uint64_t ttbr;
> @@ -559,6 +821,9 @@ static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)
>           return ret;
>   
>       domain->context_id = ret;
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +    domain->mmu->root->reg_backup[ret] = &root_pgtable[ret];
> +#endif
>   
>       /*
>        * TTBR0
> @@ -615,6 +880,9 @@ static void ipmmu_domain_destroy_context(struct ipmmu_vmsa_domain *domain)
>       ipmmu_ctx_write_root(domain, IMCTR, IMCTR_FLUSH);
>       ipmmu_tlb_sync(domain);
>   
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +    domain->mmu->root->reg_backup[domain->context_id] = NULL;
> +#endif
>       ipmmu_domain_free_context(domain->mmu->root, domain->context_id);
>   }
>   
> @@ -1340,10 +1608,11 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
>       struct iommu_fwspec *fwspec;
>   
>   #ifdef CONFIG_HAS_PCI
> +    int ret;
> +
>       if ( dev_is_pci(dev) )
>       {
>           struct pci_dev *pdev = dev_to_pci(dev);
> -        int ret;
>   
>           if ( devfn != pdev->devfn )
>               return 0;
> @@ -1371,6 +1640,15 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
>           /* Let Xen know that the master device is protected by an IOMMU. */
>           dt_device_set_protected(dev_to_dt(dev));
>       }
> +
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +    if ( ipmmu_alloc_ctx_suspend(dev) )
> +    {
> +        dev_err(dev, "Failed to allocate context for suspend\n");
> +        return -ENOMEM;
> +    }
> +#endif
> +
>   #ifdef CONFIG_HAS_PCI
>       if ( dev_is_pci(dev) )
>       {
> @@ -1379,26 +1657,28 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
>           struct pci_host_bridge *bridge;
>           struct iommu_fwspec *fwspec_bridge;
>           unsigned int utlb_osid0 = 0;
> -        int ret;
>   
>           bridge = pci_find_host_bridge(pdev->seg, pdev->bus);
>           if ( !bridge )
>           {
>               dev_err(dev, "Failed to find host bridge\n");
> -            return -ENODEV;
> +            ret = -ENODEV;
> +            goto free_suspend_ctx;
>           }
>   
>           fwspec_bridge = dev_iommu_fwspec_get(dt_to_dev(bridge->dt_node));
>           if ( fwspec_bridge->num_ids < 1 )
>           {
>               dev_err(dev, "Failed to find host bridge uTLB\n");
> -            return -ENXIO;
> +            ret = -ENXIO;
> +            goto free_suspend_ctx;
>           }
>   
>           if ( fwspec->num_ids < 1 )
>           {
>               dev_err(dev, "Failed to find uTLB");
> -            return -ENXIO;
> +            ret = -ENXIO;
> +            goto free_suspend_ctx;
>           }
>   
>           rcar4_pcie_osid_regs_init(bridge);
> @@ -1407,7 +1687,7 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
>           if ( ret < 0 )
>           {
>               dev_err(dev, "No unused OSID regs\n");
> -            return ret;
> +            goto free_suspend_ctx;
>           }
>           reg_id = ret;
>   
> @@ -1422,7 +1702,7 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
>           {
>               rcar4_pcie_osid_bdf_clear(bridge, reg_id);
>               rcar4_pcie_osid_reg_free(bridge, reg_id);
> -            return ret;
> +            goto free_suspend_ctx;
>           }
>       }
>   #endif
> @@ -1431,6 +1711,13 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
>                dev_name(fwspec->iommu_dev), fwspec->num_ids);
>   
>       return 0;
> +#ifdef CONFIG_HAS_PCI
> + free_suspend_ctx:
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +    ipmmu_free_ctx_suspend(dev);
> +#endif
> +    return ret;
> +#endif
>   }
>   
>   static int ipmmu_iommu_domain_init(struct domain *d)
> @@ -1492,6 +1779,10 @@ static const struct iommu_ops ipmmu_iommu_ops =
>       .unmap_page      = arm_iommu_unmap_page,
>       .dt_xlate        = ipmmu_dt_xlate,
>       .add_device      = ipmmu_add_device,
> +#ifdef CONFIG_SYSTEM_SUSPEND
> +    .suspend         = ipmmu_suspend,
> +    .resume          = ipmmu_resume,
> +#endif
>   };
>   
>   static __init int ipmmu_init(struct dt_device_node *node, const void *data)