[PATCH 1/1] Skip flatview_simplify() for specific cpu vendor

[FelixCuioc]

Flatview_simplify() will merge many address ranges
into one range.When a part of the big range needs
to be changed,this will cause some innocent mappings
to be unmapped.So we want to skip flatview_simplify().

Signed-off-by: FelixCuioc <FelixCui-oc@zhaoxin.com>
---
 softmmu/memory.c  | 16 +++++++++++++++-
 target/i386/cpu.c |  8 ++++++++
 target/i386/cpu.h |  3 +++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/softmmu/memory.c b/softmmu/memory.c
index 70b93104e8..348e9db622 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -699,6 +699,18 @@ static MemoryRegion 
*memory_region_get_flatview_root(MemoryRegion *mr)
     return NULL;
 }
 
+static bool skip_simplify(void)
+{
+    char vendor[CPUID_VENDOR_SZ + 1] = { 0 };
+    host_get_vendor(vendor);
+    if (!strncmp(vendor, CPUID_VENDOR_VIA, strlen(CPUID_VENDOR_VIA))
+        || !strncmp(vendor, CPUID_VENDOR_ZHAOXIN,
+                    strlen(CPUID_VENDOR_ZHAOXIN))) {
+        return true;
+    }
+    return false;
+}
+
 /* Render a memory topology into a list of disjoint absolute ranges. */
 static FlatView *generate_memory_topology(MemoryRegion *mr)
 {
@@ -712,7 +724,9 @@ static FlatView *generate_memory_topology(MemoryRegion *mr)
                              addrrange_make(int128_zero(), int128_2_64()),
                              false, false);
     }
-    flatview_simplify(view);
+    if (!skip_simplify()) {
+        flatview_simplify(view);
+    }
 
     view->dispatch = address_space_dispatch_new(view);
     for (i = 0; i < view->nr; i++) {
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 49d8958528..08508c8580 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1664,6 +1664,14 @@ void host_cpuid(uint32_t function, uint32_t count,
         *edx = vec[3];
 }
 
+void host_get_vendor(char *vendor)
+{
+    uint32_t eax, ebx, ecx, edx;
+
+    host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx);
+    x86_cpu_vendor_words2str(vendor, ebx, edx, ecx);
+}
+
 void host_vendor_fms(char *vendor, int *family, int *model, int *stepping)
 {
     uint32_t eax, ebx, ecx, edx;
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index d3097be6a5..14c8b4c09f 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -832,6 +832,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
 
 #define CPUID_VENDOR_VIA   "CentaurHauls"
 
+#define CPUID_VENDOR_ZHAOXIN   "  Shanghai  "
+
 #define CPUID_VENDOR_HYGON    "HygonGenuine"
 
 #define IS_INTEL_CPU(env) ((env)->cpuid_vendor1 == CPUID_VENDOR_INTEL_1 && \
@@ -1917,6 +1919,7 @@ void cpu_clear_apic_feature(CPUX86State *env);
 void host_cpuid(uint32_t function, uint32_t count,
                 uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx);
 void host_vendor_fms(char *vendor, int *family, int *model, int *stepping);
+void host_get_vendor(char *vendor);
 
 /* helper.c */
 bool x86_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
-- 
2.17.1