iommu/vt-d: Support size of the register set in DRHD

A new field, which indicates the size of the remapping hardware register
set for this remapping unit, is introduced in the DMA-remapping hardware
unit definition (DRHD) structure with the VT-d Spec 4.0. With this
information, SW doesn't need to 'guess' the size of the register set
anymore.

Update the struct acpi_dmar_hardware_unit to reflect the field. Store the
size of the register set in struct dmar_drhd_unit for each dmar device.

The 'size' information is ResvZ for the old BIOS and platforms. Fall back
to the old guessing method. There is nothing changed.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20230128200428.1459118-2-kan.liang@linux.intel.comSigned-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/dmar.c

@@ -427,6 +427,8 @@ static int dmar_parse_one_drhd(struct acpi_dmar_header *header, void *arg)
 	memcpy(dmaru->hdr, header, header->length);
 	dmaru->reg_base_addr = drhd->address;
 	dmaru->segment = drhd->segment;
+	/* The size of the register set is 2 ^ N 4 KB pages. */
+	dmaru->reg_size = 1UL << (drhd->size + 12);
 	dmaru->include_all = drhd->flags & 0x1; /* BIT0: INCLUDE_ALL */
 	dmaru->devices = dmar_alloc_dev_scope((void *)(drhd + 1),
 					      ((void *)drhd) + drhd->header.length,
@@ -956,17 +958,18 @@ static void unmap_iommu(struct intel_iommu *iommu)
 /**
  * map_iommu: map the iommu's registers
  * @iommu: the iommu to map
- * @phys_addr: the physical address of the base resgister
+ * @drhd: DMA remapping hardware definition structure
  *
  * Memory map the iommu's registers.  Start w/ a single page, and
  * possibly expand if that turns out to be insufficent.
  */
-static int map_iommu(struct intel_iommu *iommu, u64 phys_addr)
+static int map_iommu(struct intel_iommu *iommu, struct dmar_drhd_unit *drhd)
 {
+	u64 phys_addr = drhd->reg_base_addr;
 	int map_size, err=0;
 
 	iommu->reg_phys = phys_addr;
-	iommu->reg_size = VTD_PAGE_SIZE;
+	iommu->reg_size = drhd->reg_size;
 
 	if (!request_mem_region(iommu->reg_phys, iommu->reg_size, iommu->name)) {
 		pr_err("Can't reserve memory\n");
@@ -1050,7 +1053,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
 	}
 	sprintf(iommu->name, "dmar%d", iommu->seq_id);
 
-	err = map_iommu(iommu, drhd->reg_base_addr);
+	err = map_iommu(iommu, drhd);
 	if (err) {
 		pr_err("Failed to map %s\n", iommu->name);
 		goto error_free_seq_id;

include/acpi/actbl1.h

@@ -802,7 +802,7 @@ struct acpi_dmar_pci_path {
 struct acpi_dmar_hardware_unit {
 	struct acpi_dmar_header header;
 	u8 flags;
-	u8 reserved;
+	u8 size;		/* Size of the register set */
 	u16 segment;
 	u64 address;		/* Register Base Address */
 };

include/linux/dmar.h

@@ -39,6 +39,7 @@ struct dmar_drhd_unit {
 	struct list_head list;		/* list of drhd units	*/
 	struct  acpi_dmar_header *hdr;	/* ACPI header		*/
 	u64	reg_base_addr;		/* register base address*/
+	unsigned long reg_size;		/* size of register set */
 	struct	dmar_dev_scope *devices;/* target device array	*/
 	int	devices_cnt;		/* target device count	*/
 	u16	segment;		/* PCI domain		*/