KVM: VMX: conditionally disable 2M pages
Disable usage of 2M pages if VMX_EPT_2MB_PAGE_BIT (bit 16) is clear
in MSR_IA32_VMX_EPT_VPID_CAP and EPT is enabled.
[avi: s/largepages_disabled/largepages_enabled/ to avoid negative logic]
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 777fe53..48d5e69 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -85,6 +85,8 @@
static bool kvm_rebooting;
+static bool largepages_enabled = true;
+
#ifdef KVM_CAP_DEVICE_ASSIGNMENT
static struct kvm_assigned_dev_kernel *kvm_find_assigned_dev(struct list_head *head,
int assigned_dev_id)
@@ -1174,9 +1176,11 @@
ugfn = new.userspace_addr >> PAGE_SHIFT;
/*
* If the gfn and userspace address are not aligned wrt each
- * other, disable large page support for this slot
+ * other, or if explicitly asked to, disable large page
+ * support for this slot
*/
- if ((base_gfn ^ ugfn) & (KVM_PAGES_PER_HPAGE - 1))
+ if ((base_gfn ^ ugfn) & (KVM_PAGES_PER_HPAGE - 1) ||
+ !largepages_enabled)
for (i = 0; i < largepages; ++i)
new.lpage_info[i].write_count = 1;
}
@@ -1291,6 +1295,12 @@
return r;
}
+void kvm_disable_largepages(void)
+{
+ largepages_enabled = false;
+}
+EXPORT_SYMBOL_GPL(kvm_disable_largepages);
+
int is_error_page(struct page *page)
{
return page == bad_page;