KVM: MTRR: fix memory type handling if MTRR is completely disabled
Currently code uses default memory type if MTRR is fully disabled,
fix it by using UC instead.
Signed-off-by: Xiao Guangrong <guangrong.xiao@intel.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index de1d2d8..e275013 100644
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -120,6 +120,16 @@
return mtrr_state->deftype & IA32_MTRR_DEF_TYPE_TYPE_MASK;
}
+static u8 mtrr_disabled_type(void)
+{
+ /*
+ * Intel SDM 11.11.2.2: all MTRRs are disabled when
+ * IA32_MTRR_DEF_TYPE.E bit is cleared, and the UC
+ * memory type is applied to all of physical memory.
+ */
+ return MTRR_TYPE_UNCACHABLE;
+}
+
/*
* Three terms are used in the following code:
* - segment, it indicates the address segments covered by fixed MTRRs.
@@ -434,6 +444,8 @@
/* output fields. */
int mem_type;
+ /* mtrr is completely disabled? */
+ bool mtrr_disabled;
/* [start, end) is not fully covered in MTRRs? */
bool partial_map;
@@ -549,7 +561,7 @@
static void mtrr_lookup_start(struct mtrr_iter *iter)
{
if (!mtrr_is_enabled(iter->mtrr_state)) {
- iter->partial_map = true;
+ iter->mtrr_disabled = true;
return;
}
@@ -563,6 +575,7 @@
iter->mtrr_state = mtrr_state;
iter->start = start;
iter->end = end;
+ iter->mtrr_disabled = false;
iter->partial_map = false;
iter->fixed = false;
iter->range = NULL;
@@ -656,6 +669,9 @@
return MTRR_TYPE_WRBACK;
}
+ if (iter.mtrr_disabled)
+ return mtrr_disabled_type();
+
/* It is not covered by MTRRs. */
if (iter.partial_map) {
/*
@@ -689,6 +705,9 @@
return false;
}
+ if (iter.mtrr_disabled)
+ return true;
+
if (!iter.partial_map)
return true;
