x86: Setup fixed range MTRRs for legacy regions
We should setup fixed range MTRRs for some legacy regions like VGA
RAM and PCI ROM areas as uncacheable. Note FSP may setup these to
other cache settings, but we can override this in x86_cpu_init_f().
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
index d108ee5..9afdafb 100644
--- a/arch/x86/cpu/cpu.c
+++ b/arch/x86/cpu/cpu.c
@@ -28,6 +28,8 @@
#include <asm/cpu.h>
#include <asm/lapic.h>
#include <asm/mp.h>
+#include <asm/msr.h>
+#include <asm/mtrr.h>
#include <asm/post.h>
#include <asm/processor.h>
#include <asm/processor-flags.h>
@@ -352,6 +354,26 @@
gd->arch.has_mtrr = has_mtrr();
}
+ /* Configure fixed range MTRRs for some legacy regions */
+ if (gd->arch.has_mtrr) {
+ u64 mtrr_cap;
+
+ mtrr_cap = native_read_msr(MTRR_CAP_MSR);
+ if (mtrr_cap & MTRR_CAP_FIX) {
+ /* Mark the VGA RAM area as uncacheable */
+ native_write_msr(MTRR_FIX_16K_A0000_MSR, 0, 0);
+
+ /* Mark the PCI ROM area as uncacheable */
+ native_write_msr(MTRR_FIX_4K_C0000_MSR, 0, 0);
+ native_write_msr(MTRR_FIX_4K_C8000_MSR, 0, 0);
+ native_write_msr(MTRR_FIX_4K_D0000_MSR, 0, 0);
+ native_write_msr(MTRR_FIX_4K_D8000_MSR, 0, 0);
+
+ /* Enable the fixed range MTRRs */
+ msr_setbits_64(MTRR_DEF_TYPE_MSR, MTRR_DEF_TYPE_FIX_EN);
+ }
+ }
+
return 0;
}