x86: Simplify DMAR unit discovery

Perform counting and resource allocation before iterating over all
units. This not only allows to drop some code but also removes the
restrictive allocation pattern for the unit MMIO and invalidation queue
pages.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

diff --git a/hypervisor/arch/x86/vtd.c b/hypervisor/arch/x86/vtd.c
index 201bc202918ea5fe2dc5fd81ef3f71d59dee961d..699e6d83969feec74b8e077943e239f92ad420a0 100644 (file)
--- a/hypervisor/arch/x86/vtd.c
+++ b/hypervisor/arch/x86/vtd.c
@@ -254,7 +254,8 @@ int vtd_init(void)
 {
        unsigned long size, version, caps, ecaps, sllps_caps = ~0UL;
        unsigned int pt_levels, num_did, n;
-       void *reg_base, *inv_queue;
+       unsigned int units = 0;
+       void *reg_base;
        u64 base_addr;
        int err;
 
@@ -271,23 +272,20 @@ int vtd_init(void)
 
        int_remap_table_size_log2 = n;
 
-       for (n = 0; n < JAILHOUSE_MAX_DMAR_UNITS; n++) {
-               base_addr = system_config->platform_info.x86.dmar_unit_base[n];
-               if (base_addr == 0)
-                       break;
+       while (system_config->platform_info.x86.dmar_unit_base[units])
+               units++;
+       if (units == 0)
+               return -EINVAL;
 
-               reg_base = page_alloc(&remap_pool, 1);
-               inv_queue = page_alloc(&mem_pool, 1);
-               if (!reg_base || !inv_queue)
-                       return -ENOMEM;
+       dmar_reg_base = page_alloc(&remap_pool, units);
+       unit_inv_queue = page_alloc(&mem_pool, units);
+       if (!dmar_reg_base || !unit_inv_queue)
+               return -ENOMEM;
 
-               if (dmar_units == 0) {
-                       dmar_reg_base = reg_base;
-                       unit_inv_queue = inv_queue;
-               }
-               if (reg_base != dmar_reg_base + dmar_units * PAGE_SIZE ||
-                   inv_queue != unit_inv_queue + dmar_units * PAGE_SIZE)
-                       return -ENOMEM;
+       for (n = 0; n < units; n++) {
+               base_addr = system_config->platform_info.x86.dmar_unit_base[n];
+
+               reg_base = dmar_reg_base + n * PAGE_SIZE;
 
                err = page_map_create(&hv_paging_structs, base_addr, PAGE_SIZE,
                                      (unsigned long)reg_base,
@@ -332,12 +330,9 @@ int vtd_init(void)
                num_did = 1 << (4 + (caps & VTD_CAP_NUM_DID_MASK) * 2);
                if (num_did < dmar_num_did)
                        dmar_num_did = num_did;
-
-               dmar_units++;
        }
 
-       if (dmar_units == 0)
-               return -EINVAL;
+       dmar_units = units;
 
        /*
         * Derive vdt_paging from very similar x86_64_paging,