From 54dee9933e8d93589ad63ec3d6be39f1921b0767 Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Thu, 11 Jun 2009 12:07:44 -0300
Subject: [PATCH] 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>
---
arch/x86/kvm/vmx.c | 3 +++
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 14 ++++++++++++--
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 94c07ada103e9..fc8d49c6bc516 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1381,6 +1381,9 @@ static __init int hardware_setup(void)
if (!cpu_has_vmx_tpr_shadow())
kvm_x86_ops->update_cr8_intercept = NULL;
+ if (enable_ept && !cpu_has_vmx_ept_2m_page())
+ kvm_disable_largepages();
+
return alloc_kvm_area();
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c6e4d02067fed..6988858dc56ee 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -224,6 +224,7 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
struct kvm_memory_slot old,
int user_alloc);
+void kvm_disable_largepages(void);
void kvm_arch_flush_shadow(struct kvm *kvm);
gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn);
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 777fe533cfe73..48d5e697bf44b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -85,6 +85,8 @@ static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
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 @@ int __kvm_set_memory_region(struct kvm *kvm,
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 @@ out:
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;
--
2.30.2