roms: Flush icache when writing roms to guest memory

We use the rom infrastructure to write firmware and/or initial kernel
blobs into guest address space. So we're basically emulating the cache
off phase on very early system bootup.

That phase is usually responsible for clearing the instruction cache for
anything it writes into cachable memory, to ensure that after reboot we
don't happen to execute stale bits from the instruction cache.

So we need to invalidate the icache every time we write a rom into guest
address space. We do not need to do this for every DMA since the guest
expects it has to flush the icache manually in that case.

This fixes random reboot issues on e5500 (booke ppc) for me.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 39 insertions, 5 deletions

diff --git a/exec.c b/exec.c
index f4b9ef25f5..896f7b83fc 100644
--- a/exec.c
+++ b/exec.c
@@ -50,6 +50,7 @@
 #include "translate-all.h"
 
 #include "exec/memory-internal.h"
+#include "qemu/cache-utils.h"
 
 //#define DEBUG_SUBPAGE
 
@@ -2010,9 +2011,13 @@ void cpu_physical_memory_rw(hwaddr addr, uint8_t *buf,
     address_space_rw(&address_space_memory, addr, buf, len, is_write);
 }
 
-/* used for ROM loading : can write in RAM and ROM */
-void cpu_physical_memory_write_rom(hwaddr addr,
-                                   const uint8_t *buf, int len)
+enum write_rom_type {
+    WRITE_DATA,
+    FLUSH_CACHE,
+};
+
+static inline void cpu_physical_memory_write_rom_internal(
+    hwaddr addr, const uint8_t *buf, int len, enum write_rom_type type)
 {
     hwaddr l;
     uint8_t *ptr;
@@ -2031,8 +2036,15 @@ void cpu_physical_memory_write_rom(hwaddr addr,
             addr1 += memory_region_get_ram_addr(mr);
             /* ROM/RAM case */
             ptr = qemu_get_ram_ptr(addr1);
-            memcpy(ptr, buf, l);
-            invalidate_and_set_dirty(addr1, l);
+            switch (type) {
+            case WRITE_DATA:
+                memcpy(ptr, buf, l);
+                invalidate_and_set_dirty(addr1, l);
+                break;
+            case FLUSH_CACHE:
+                flush_icache_range((uintptr_t)ptr, (uintptr_t)ptr + l);
+                break;
+            }
         }
         len -= l;
         buf += l;
@@ -2040,6 +2052,28 @@ void cpu_physical_memory_write_rom(hwaddr addr,
     }
 }
 
+/* used for ROM loading : can write in RAM and ROM */
+void cpu_physical_memory_write_rom(hwaddr addr,
+                                   const uint8_t *buf, int len)
+{
+    cpu_physical_memory_write_rom_internal(addr, buf, len, WRITE_DATA);
+}
+
+void cpu_flush_icache_range(hwaddr start, int len)
+{
+    /*
+     * This function should do the same thing as an icache flush that was
+     * triggered from within the guest. For TCG we are always cache coherent,
+     * so there is no need to flush anything. For KVM / Xen we need to flush
+     * the host's instruction cache at least.
+     */
+    if (tcg_enabled()) {
+        return;
+    }
+
+    cpu_physical_memory_write_rom_internal(start, NULL, len, FLUSH_CACHE);
+}
+
 typedef struct {
     MemoryRegion *mr;
     void *buffer;