[PATCH v5 27/46] x86: emulation: Set an MTRR for the RAM

[Simon Glass]

QEMU likes to have an MTRR set up, just like real machines. Add an MTRR
which covers the total RAM size.

This does nothing on machines without MTRRs.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

(no changes since v3)

Changes in v3:
- Support memory sizes above 3GB properly

Changes in v2:
- Add new patch to set an MTRR for the RAM in QEMU

 arch/x86/cpu/qemu/dram.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/x86/cpu/qemu/dram.c b/arch/x86/cpu/qemu/dram.c
index 62a301c0fd3..ba3638e6acc 100644
--- a/arch/x86/cpu/qemu/dram.c
+++ b/arch/x86/cpu/qemu/dram.c
@@ -4,7 +4,9 @@
  */
 
 #include <init.h>
+#include <spl.h>
 #include <asm/global_data.h>
+#include <asm/mtrr.h>
 #include <asm/post.h>
 #include <asm/arch/qemu.h>
 #include <linux/sizes.h>
@@ -44,6 +46,22 @@ int dram_init(void)
 	gd->ram_size += qemu_get_high_memory_size();
 	post_code(POST_DRAM);
 
+	if (xpl_phase() == PHASE_BOARD_F) {
+		u64 total = gd->ram_size;
+		int ret;
+
+		if (total > SZ_2G + SZ_1G)
+			total += SZ_1G;
+		ret = mtrr_add_request(MTRR_TYPE_WRBACK, 0, total);
+		if (ret != -ENOSYS) {
+			if (ret)
+				return log_msg_ret("mta", ret);
+			ret = mtrr_commit(false);
+			if (ret)
+				return log_msg_ret("mtc", ret);
+		}
+	}
+
 	return 0;
 }
 
-- 
2.43.0