[Xen-devel] [PATCH v2 09/10] AMD/IOMMU: enable x2APIC mode when available

["Jan Beulich" <JBeulich@xxxxxxxx>]

In order for the CPUs to use x2APIC mode, the IOMMU(s) first need to be
switched into suitable state.

The post-AP-bringup IRQ affinity adjustment is done also for the non-
x2APIC case.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Drop cpu_has_cx16 check. Add comment.
---
TBD: Instead of the system_state check in iov_enable_xt() the function
     could also zap its own hook pointer, at which point it could also
     become __init. This would, however, require that either
     resume_x2apic() be bound to ignore iommu_enable_x2apic() errors
     forever, or that iommu_enable_x2apic() be slightly re-arranged to
     not return -EOPNOTSUPP when finding a NULL hook during resume.

--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -834,6 +834,30 @@ static bool_t __init set_iommu_interrupt
     return 1;
 }
 
+int iov_adjust_irq_affinities(void)
+{
+    const struct amd_iommu *iommu;
+
+    if ( !iommu_enabled )
+        return 0;
+
+    for_each_amd_iommu ( iommu )
+    {
+        struct irq_desc *desc = irq_to_desc(iommu->msi.irq);
+        unsigned long flags;
+
+        spin_lock_irqsave(&desc->lock, flags);
+        if ( iommu->ctrl.int_cap_xt_en )
+            set_x2apic_affinity(desc, &cpu_online_map);
+        else
+            set_msi_affinity(desc, &cpu_online_map);
+        spin_unlock_irqrestore(&desc->lock, flags);
+    }
+
+    return 0;
+}
+__initcall(iov_adjust_irq_affinities);
+
 /*
  * Family15h Model 10h-1fh erratum 746 (IOMMU Logging May Stall Translations)
  * Workaround:
@@ -1047,7 +1071,7 @@ static void * __init allocate_ppr_log(st
                                 IOMMU_PPR_LOG_DEFAULT_ENTRIES, "PPR Log");
 }
 
-static int __init amd_iommu_init_one(struct amd_iommu *iommu)
+static int __init amd_iommu_init_one(struct amd_iommu *iommu, bool intr)
 {
     if ( allocate_cmd_buffer(iommu) == NULL )
         goto error_out;
@@ -1058,7 +1082,7 @@ static int __init amd_iommu_init_one(str
     if ( iommu->features.flds.ppr_sup && !allocate_ppr_log(iommu) )
         goto error_out;
 
-    if ( !set_iommu_interrupt_handler(iommu) )
+    if ( intr && !set_iommu_interrupt_handler(iommu) )
         goto error_out;
 
     /* To make sure that device_table.buffer has been successfully allocated */
@@ -1285,7 +1309,7 @@ static int __init amd_iommu_prepare_one(
     return 0;
 }
 
-int __init amd_iommu_init(void)
+int __init amd_iommu_prepare(void)
 {
     struct amd_iommu *iommu;
     int rc = -ENODEV;
@@ -1300,9 +1324,14 @@ int __init amd_iommu_init(void)
     if ( unlikely(acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_MSI) )
         goto error_out;
 
+    /* Have we been here before? */
+    if ( ivhd_type )
+        return 0;
+
     rc = amd_iommu_get_supported_ivhd_type();
     if ( rc < 0 )
         goto error_out;
+    BUG_ON(!rc);
     ivhd_type = rc;
 
     rc = amd_iommu_get_ivrs_dev_entries();
@@ -1321,9 +1350,33 @@ int __init amd_iommu_init(void)
     }
 
     rc = amd_iommu_update_ivrs_mapping_acpi();
+
+ error_out:
+    if ( rc )
+    {
+        amd_iommu_init_cleanup();
+        ivhd_type = 0;
+    }
+
+    return rc;
+}
+
+int __init amd_iommu_init(bool xt)
+{
+    struct amd_iommu *iommu;
+    int rc = amd_iommu_prepare();
+
     if ( rc )
         goto error_out;
 
+    for_each_amd_iommu ( iommu )
+    {
+        /* NB: There's no need to actually write these out right here. */
+        iommu->ctrl.ga_en |= xt;
+        iommu->ctrl.xt_en = xt;
+        iommu->ctrl.int_cap_xt_en = xt;
+    }
+
     /* initialize io-apic interrupt remapping entries */
     if ( iommu_intremap )
         rc = amd_iommu_setup_ioapic_remapping();
@@ -1346,7 +1399,12 @@ int __init amd_iommu_init(void)
     /* per iommu initialization  */
     for_each_amd_iommu ( iommu )
     {
-        rc = amd_iommu_init_one(iommu);
+        /*
+         * Setting up of the IOMMU interrupts cannot occur yet at the (very
+         * early) time we get here when enabling x2APIC mode. Suppress it
+         * here, and do it explicitly in amd_iommu_init_interrupt().
+         */
+        rc = amd_iommu_init_one(iommu, !xt);
         if ( rc )
             goto error_out;
     }
@@ -1358,6 +1416,40 @@ error_out:
     return rc;
 }
 
+int __init amd_iommu_init_interrupt(void)
+{
+    struct amd_iommu *iommu;
+    int rc = 0;
+
+    for_each_amd_iommu ( iommu )
+    {
+        struct irq_desc *desc;
+
+        if ( !set_iommu_interrupt_handler(iommu) )
+        {
+            rc = -EIO;
+            break;
+        }
+
+        desc = irq_to_desc(iommu->msi.irq);
+
+        spin_lock(&desc->lock);
+        ASSERT(iommu->ctrl.int_cap_xt_en);
+        set_x2apic_affinity(desc, &cpu_online_map);
+        spin_unlock(&desc->lock);
+
+        set_iommu_event_log_control(iommu, IOMMU_CONTROL_ENABLED);
+
+        if ( iommu->features.flds.ppr_sup )
+            set_iommu_ppr_log_control(iommu, IOMMU_CONTROL_ENABLED);
+    }
+
+    if ( rc )
+        amd_iommu_init_cleanup();
+
+    return rc;
+}
+
 static void invalidate_all_domain_pages(void)
 {
     struct domain *d;
--- a/xen/drivers/passthrough/amd/iommu_intr.c
+++ b/xen/drivers/passthrough/amd/iommu_intr.c
@@ -816,6 +816,40 @@ void* __init amd_iommu_alloc_intremap_ta
     return tb;
 }
 
+bool __init iov_supports_xt(void)
+{
+    unsigned int apic;
+    struct amd_iommu *iommu;
+
+    if ( !iommu_enable || !iommu_intremap )
+        return false;
+
+    if ( amd_iommu_prepare() )
+        return false;
+
+    for_each_amd_iommu ( iommu )
+        if ( !iommu->features.flds.ga_sup || !iommu->features.flds.xt_sup )
+            return false;
+
+    for ( apic = 0; apic < nr_ioapics; apic++ )
+    {
+        unsigned int idx = ioapic_id_to_index(IO_APIC_ID(apic));
+
+        if ( idx == MAX_IO_APICS )
+            return false;
+
+        if ( !find_iommu_for_device(ioapic_sbdf[idx].seg,
+                                    ioapic_sbdf[idx].bdf) )
+        {
+            AMD_IOMMU_DEBUG("No IOMMU for IO-APIC %#x (ID %x)\n",
+                            apic, IO_APIC_ID(apic));
+            return false;
+        }
+    }
+
+    return true;
+}
+
 int __init amd_setup_hpet_msi(struct msi_desc *msi_desc)
 {
     spinlock_t *lock;
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -170,7 +170,8 @@ static int __init iov_detect(void)
     if ( !iommu_enable && !iommu_intremap )
         return 0;
 
-    if ( amd_iommu_init() != 0 )
+    else if ( (init_done ? amd_iommu_init_interrupt()
+                         : amd_iommu_init(false)) != 0 )
     {
         printk("AMD-Vi: Error initialization\n");
         return -ENODEV;
@@ -183,6 +184,25 @@ static int __init iov_detect(void)
     return scan_pci_devices();
 }
 
+static int iov_enable_xt(void)
+{
+    int rc;
+
+    if ( system_state >= SYS_STATE_active )
+        return 0;
+
+    if ( (rc = amd_iommu_init(true)) != 0 )
+    {
+        printk("AMD-Vi: Error %d initializing for x2APIC mode\n", rc);
+        /* -ENXIO has special meaning to the caller - convert it. */
+        return rc != -ENXIO ? rc : -ENODATA;
+    }
+
+    init_done = true;
+
+    return 0;
+}
+
 int amd_iommu_alloc_root(struct domain_iommu *hd)
 {
     if ( unlikely(!hd->arch.root_table) )
@@ -559,11 +579,13 @@ static const struct iommu_ops __initcons
     .free_page_table = deallocate_page_table,
     .reassign_device = reassign_device,
     .get_device_group_id = amd_iommu_group_id,
+    .enable_x2apic = iov_enable_xt,
     .update_ire_from_apic = amd_iommu_ioapic_update_ire,
     .update_ire_from_msi = amd_iommu_msi_msg_update_ire,
     .read_apic_from_ire = amd_iommu_read_ioapic_from_ire,
     .read_msi_from_ire = amd_iommu_read_msi_from_ire,
     .setup_hpet_msi = amd_setup_hpet_msi,
+    .adjust_irq_affinities = iov_adjust_irq_affinities,
     .suspend = amd_iommu_suspend,
     .resume = amd_iommu_resume,
     .share_p2m = amd_iommu_share_p2m,
@@ -574,4 +596,5 @@ static const struct iommu_ops __initcons
 static const struct iommu_init_ops __initconstrel _iommu_init_ops = {
     .ops = &_iommu_ops,
     .setup = iov_detect,
+    .supports_x2apic = iov_supports_xt,
 };
--- a/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
@@ -48,8 +48,11 @@ int amd_iommu_detect_acpi(void);
 void get_iommu_features(struct amd_iommu *iommu);
 
 /* amd-iommu-init functions */
-int amd_iommu_init(void);
+int amd_iommu_prepare(void);
+int amd_iommu_init(bool xt);
+int amd_iommu_init_interrupt(void);
 int amd_iommu_update_ivrs_mapping_acpi(void);
+int iov_adjust_irq_affinities(void);
 
 /* mapping functions */
 int __must_check amd_iommu_map_page(struct domain *d, dfn_t dfn,
@@ -96,6 +99,7 @@ void amd_iommu_flush_all_caches(struct a
 struct amd_iommu *find_iommu_for_device(int seg, int bdf);
 
 /* interrupt remapping */
+bool iov_supports_xt(void);
 int amd_iommu_setup_ioapic_remapping(void);
 void *amd_iommu_alloc_intremap_table(unsigned long **);
 int amd_iommu_free_intremap_table(u16 seg, struct ivrs_mappings *);




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