iommu/vt-d: Implement DMAR unit hotplug framework

On Intel platforms, an IO Hub (PCI/PCIe host bridge) may contain DMAR
units, so we need to support DMAR hotplug when supporting PCI host
bridge hotplug on Intel platforms.

According to Section 8.8 "Remapping Hardware Unit Hot Plug" in "Intel
Virtualization Technology for Directed IO Architecture Specification
Rev 2.2", ACPI BIOS should implement ACPI _DSM method under the ACPI
object for the PCI host bridge to support DMAR hotplug.

This patch introduces interfaces to parse ACPI _DSM method for
DMAR unit hotplug. It also implements state machines for DMAR unit
hot-addition and hot-removal.

The PCI host bridge hotplug driver should call dmar_hotplug_hotplug()
before scanning PCI devices connected for hot-addition and after
destroying all PCI devices for hot-removal.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Reviewed-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 75 insertions, 3 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 2779354321f5..7c49ab51904f 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3703,17 +3703,48 @@ int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg)
 	return 0;
 }
 
-int __init dmar_parse_one_atsr(struct acpi_dmar_header *hdr, void *arg)
+static struct dmar_atsr_unit *dmar_find_atsr(struct acpi_dmar_atsr *atsr)
+{
+	struct dmar_atsr_unit *atsru;
+	struct acpi_dmar_atsr *tmp;
+
+	list_for_each_entry_rcu(atsru, &dmar_atsr_units, list) {
+		tmp = (struct acpi_dmar_atsr *)atsru->hdr;
+		if (atsr->segment != tmp->segment)
+			continue;
+		if (atsr->header.length != tmp->header.length)
+			continue;
+		if (memcmp(atsr, tmp, atsr->header.length) == 0)
+			return atsru;
+	}
+
+	return NULL;
+}
+
+int dmar_parse_one_atsr(struct acpi_dmar_header *hdr, void *arg)
 {
 	struct acpi_dmar_atsr *atsr;
 	struct dmar_atsr_unit *atsru;
 
+	if (system_state != SYSTEM_BOOTING && !intel_iommu_enabled)
+		return 0;
+
 	atsr = container_of(hdr, struct acpi_dmar_atsr, header);
-	atsru = kzalloc(sizeof(*atsru), GFP_KERNEL);
+	atsru = dmar_find_atsr(atsr);
+	if (atsru)
+		return 0;
+
+	atsru = kzalloc(sizeof(*atsru) + hdr->length, GFP_KERNEL);
 	if (!atsru)
 		return -ENOMEM;
 
-	atsru->hdr = hdr;
+	/*
+	 * If memory is allocated from slab by ACPI _DSM method, we need to
+	 * copy the memory content because the memory buffer will be freed
+	 * on return.
+	 */
+	atsru->hdr = (void *)(atsru + 1);
+	memcpy(atsru->hdr, hdr, hdr->length);
 	atsru->include_all = atsr->flags & 0x1;
 	if (!atsru->include_all) {
 		atsru->devices = dmar_alloc_dev_scope((void *)(atsr + 1),
@@ -3736,6 +3767,47 @@ static void intel_iommu_free_atsr(struct dmar_atsr_unit *atsru)
 	kfree(atsru);
 }
 
+int dmar_release_one_atsr(struct acpi_dmar_header *hdr, void *arg)
+{
+	struct acpi_dmar_atsr *atsr;
+	struct dmar_atsr_unit *atsru;
+
+	atsr = container_of(hdr, struct acpi_dmar_atsr, header);
+	atsru = dmar_find_atsr(atsr);
+	if (atsru) {
+		list_del_rcu(&atsru->list);
+		synchronize_rcu();
+		intel_iommu_free_atsr(atsru);
+	}
+
+	return 0;
+}
+
+int dmar_check_one_atsr(struct acpi_dmar_header *hdr, void *arg)
+{
+	int i;
+	struct device *dev;
+	struct acpi_dmar_atsr *atsr;
+	struct dmar_atsr_unit *atsru;
+
+	atsr = container_of(hdr, struct acpi_dmar_atsr, header);
+	atsru = dmar_find_atsr(atsr);
+	if (!atsru)
+		return 0;
+
+	if (!atsru->include_all && atsru->devices && atsru->devices_cnt)
+		for_each_active_dev_scope(atsru->devices, atsru->devices_cnt,
+					  i, dev)
+			return -EBUSY;
+
+	return 0;
+}
+
+int dmar_iommu_hotplug(struct dmar_drhd_unit *dmaru, bool insert)
+{
+	return intel_iommu_enabled ? -ENOSYS : 0;
+}
+
 static void intel_iommu_free_dmars(void)
 {
 	struct dmar_rmrr_unit *rmrru, *rmrr_n;