hvf: non-RAM, non-ROMD memory ranges are now correctly mapped in

If an area is non-RAM and non-ROMD, then remove mappings so accesses
will trap and can be emulated.  Change hvf_find_overlap_slot() to take
a size instead of an end address: it wouldn't return a slot because
callers would pass the same address for start and end.  Don't always
map area as read/write/execute, respect area flags.

Signed-off-by: Cameron Esfahani <dirty@apple.com>
Message-Id: <1d8476c8f86959273fbdf23c86f8b4b611f5e2e1.1574625592.git.dirty@apple.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/hvf/hvf.c

@@ -107,14 +107,14 @@ static void assert_hvf_ok(hv_return_t ret)
 }
 
 /* Memory slots */
-hvf_slot *hvf_find_overlap_slot(uint64_t start, uint64_t end)
+hvf_slot *hvf_find_overlap_slot(uint64_t start, uint64_t size)
 {
     hvf_slot *slot;
     int x;
     for (x = 0; x < hvf_state->num_slots; ++x) {
         slot = &hvf_state->slots[x];
         if (slot->size && start < (slot->start + slot->size) &&
-            end > slot->start) {
+            (start + size) > slot->start) {
             return slot;
         }
     }
@@ -129,12 +129,10 @@ struct mac_slot {
 };
 
 struct mac_slot mac_slots[32];
-#define ALIGN(x, y)  (((x) + (y) - 1) & ~((y) - 1))
 
-static int do_hvf_set_memory(hvf_slot *slot)
+static int do_hvf_set_memory(hvf_slot *slot, hv_memory_flags_t flags)
 {
     struct mac_slot *macslot;
-    hv_memory_flags_t flags;
     hv_return_t ret;
 
     macslot = &mac_slots[slot->slot_id];
@@ -151,8 +149,6 @@ static int do_hvf_set_memory(hvf_slot *slot)
         return 0;
     }
 
-    flags = HV_MEMORY_READ | HV_MEMORY_WRITE | HV_MEMORY_EXEC;
-
     macslot->present = 1;
     macslot->gpa_start = slot->start;
     macslot->size = slot->size;
@@ -165,14 +161,24 @@ void hvf_set_phys_mem(MemoryRegionSection *section, bool add)
 {
     hvf_slot *mem;
     MemoryRegion *area = section->mr;
+    bool writeable = !area->readonly && !area->rom_device;
+    hv_memory_flags_t flags;
 
     if (!memory_region_is_ram(area)) {
-        return;
+        if (writeable) {
+            return;
+        } else if (!memory_region_is_romd(area)) {
+            /*
+             * If the memory device is not in romd_mode, then we actually want
+             * to remove the hvf memory slot so all accesses will trap.
+             */
+             add = false;
+        }
     }
 
     mem = hvf_find_overlap_slot(
             section->offset_within_address_space,
-            section->offset_within_address_space + int128_get64(section->size));
+            int128_get64(section->size));
 
     if (mem && add) {
         if (mem->size == int128_get64(section->size) &&
@@ -186,7 +192,7 @@ void hvf_set_phys_mem(MemoryRegionSection *section, bool add)
     /* Region needs to be reset. set the size to 0 and remap it. */
     if (mem) {
         mem->size = 0;
-        if (do_hvf_set_memory(mem)) {
+        if (do_hvf_set_memory(mem, 0)) {
             error_report("Failed to reset overlapping slot");
             abort();
         }
@@ -196,6 +202,13 @@ void hvf_set_phys_mem(MemoryRegionSection *section, bool add)
         return;
     }
 
+    if (area->readonly ||
+        (!memory_region_is_ram(area) && memory_region_is_romd(area))) {
+        flags = HV_MEMORY_READ | HV_MEMORY_EXEC;
+    } else {
+        flags = HV_MEMORY_READ | HV_MEMORY_WRITE | HV_MEMORY_EXEC;
+    }
+
     /* Now make a new slot. */
     int x;
 
@@ -216,7 +229,7 @@ void hvf_set_phys_mem(MemoryRegionSection *section, bool add)
     mem->start = section->offset_within_address_space;
     mem->region = area;
 
-    if (do_hvf_set_memory(mem)) {
+    if (do_hvf_set_memory(mem, flags)) {
         error_report("Error registering new memory slot");
         abort();
     }
@@ -345,7 +358,14 @@ static bool ept_emulation_fault(hvf_slot *slot, uint64_t gpa, uint64_t ept_qual)
         return false;
     }
 
-    return !slot;
+    if (!slot) {
+        return true;
+    }
+    if (!memory_region_is_ram(slot->region) &&
+        !(read && memory_region_is_romd(slot->region))) {
+        return true;
+    }
+    return false;
 }
 
 static void hvf_set_dirty_tracking(MemoryRegionSection *section, bool on)
@@ -354,7 +374,7 @@ static void hvf_set_dirty_tracking(MemoryRegionSection *section, bool on)
 
     slot = hvf_find_overlap_slot(
             section->offset_within_address_space,
-            section->offset_within_address_space + int128_get64(section->size));
+            int128_get64(section->size));
 
     /* protect region against writes; begin tracking it */
     if (on) {
@@ -720,7 +740,7 @@ int hvf_vcpu_exec(CPUState *cpu)
             ret = EXCP_INTERRUPT;
             break;
         }
-            /* Need to check if MMIO or unmmaped fault */
+        /* Need to check if MMIO or unmapped fault */
         case EXIT_REASON_EPT_FAULT:
         {
             hvf_slot *slot;
@@ -731,7 +751,7 @@ int hvf_vcpu_exec(CPUState *cpu)
                 vmx_set_nmi_blocking(cpu);
             }
 
-            slot = hvf_find_overlap_slot(gpa, gpa);
+            slot = hvf_find_overlap_slot(gpa, 1);
             /* mmio */
             if (ept_emulation_fault(slot, gpa, exit_qual)) {
                 struct x86_decode decode;