[PATCH 1/2] hw/arm/virt: Improve address assignment for highmem IO regions

[Gavin Shan]

There are 3 highmem IO regions as below. They can be disabled in
two situations: (a) The specific region is disabled by user. (b)
The specific region doesn't fit in the PA space. However, the base
address and highest_gpa are still updated no matter if the region
is enabled or disabled. It's incorrectly incurring waste in the PA
space.

Improve address assignment for highmem IO regions to avoid the waste
in the PA space by putting the logic into virt_memmap_fits().

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 hw/arm/virt.c | 54 +++++++++++++++++++++++++++++----------------------
 1 file changed, 31 insertions(+), 23 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 9633f822f3..bc0cd218f9 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1688,6 +1688,34 @@ static uint64_t virt_cpu_mp_affinity(VirtMachineState 
*vms, int idx)
     return arm_cpu_mp_affinity(idx, clustersz);
 }
 
+static void virt_memmap_fits(VirtMachineState *vms, int index,
+                             bool *enabled, hwaddr *base, int pa_bits)
+{
+    hwaddr size = extended_memmap[index].size;
+
+    /* The region will be disabled if its size isn't given */
+    if (!*enabled || !size) {
+        *enabled = false;
+        vms->memmap[index].base = 0;
+        vms->memmap[index].size = 0;
+        return;
+    }
+
+    /*
+     * Check if the memory region fits in the PA space. The memory map
+     * and highest_gpa are updated if it fits. Otherwise, it's disabled.
+     */
+    *enabled = (ROUND_UP(*base, size) + size <= BIT_ULL(pa_bits));
+    if (*enabled) {
+        *base = ROUND_UP(*base, size);
+        vms->memmap[index].base = *base;
+        vms->memmap[index].size = size;
+        vms->highest_gpa = *base + size - 1;
+
+       *base = *base + size;
+    }
+}
+
 static void virt_set_memmap(VirtMachineState *vms, int pa_bits)
 {
     MachineState *ms = MACHINE(vms);
@@ -1744,37 +1772,17 @@ static void virt_set_memmap(VirtMachineState *vms, int 
pa_bits)
     vms->highest_gpa = memtop - 1;
 
     for (i = VIRT_LOWMEMMAP_LAST; i < ARRAY_SIZE(extended_memmap); i++) {
-        hwaddr size = extended_memmap[i].size;
-        bool fits;
-
-        base = ROUND_UP(base, size);
-        vms->memmap[i].base = base;
-        vms->memmap[i].size = size;
-
-        /*
-         * Check each device to see if they fit in the PA space,
-         * moving highest_gpa as we go.
-         *
-         * For each device that doesn't fit, disable it.
-         */
-        fits = (base + size) <= BIT_ULL(pa_bits);
-        if (fits) {
-            vms->highest_gpa = base + size - 1;
-        }
-
         switch (i) {
         case VIRT_HIGH_GIC_REDIST2:
-            vms->highmem_redists &= fits;
+            virt_memmap_fits(vms, i, &vms->highmem_redists, &base, pa_bits);
             break;
         case VIRT_HIGH_PCIE_ECAM:
-            vms->highmem_ecam &= fits;
+            virt_memmap_fits(vms, i, &vms->highmem_ecam, &base, pa_bits);
             break;
         case VIRT_HIGH_PCIE_MMIO:
-            vms->highmem_mmio &= fits;
+            virt_memmap_fits(vms, i, &vms->highmem_mmio, &base, pa_bits);
             break;
         }
-
-        base += size;
     }
 
     if (device_memory_size > 0) {
-- 
2.23.0