In this patch we add a list of L0 (hardware) VMCSs, which we'll use to hold a
hardware VMCS for each active L1 VMCS (i.e., for each L2 guest).
We call each of these L0 VMCSs a vmcs02, as it is the VMCS that L0 uses
to run its nested guest L2.
Signed-off-by: Nadav Har'El n...@il.ibm.com
---
--- .before/arch/x86/kvm/vmx.c 2010-06-13 15:01:29.0 +0300
+++ .after/arch/x86/kvm/vmx.c 2010-06-13 15:01:29.0 +0300
@@ -140,6 +140,12 @@ struct __attribute__ ((__packed__)) vmcs
u32 abort;
};
+struct vmcs_list {
+ struct list_head list;
+ gpa_t vmcs_addr;
+ struct vmcs *l2_vmcs;
+};
+
/* The nested_vmx structure is part of vcpu_vmx, and holds information we need
* for correct emulation of VMX (i.e., nested VMX) on this vcpu. For example,
* the current VMCS set by L1, a list of the VMCSs used to run the active
@@ -153,6 +159,10 @@ struct nested_vmx {
gpa_t current_vmptr;
/* The host-usable pointer to the above. Set by nested_map_current() */
struct vmcs12 *current_l2_page;
+
+ /* list of real (hardware) VMCS, one for each L2 guest of L1 */
+ struct list_head l2_vmcs_list; /* a vmcs_list */
+ int l2_vmcs_num;
};
struct vcpu_vmx {
@@ -1754,6 +1764,84 @@ static void free_vmcs(struct vmcs *vmcs)
free_pages((unsigned long)vmcs, vmcs_config.order);
}
+static struct vmcs *nested_get_current_vmcs(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct vmcs_list *list_item, *n;
+
+ list_for_each_entry_safe(list_item, n, vmx-nested.l2_vmcs_list, list)
+ if (list_item-vmcs_addr == vmx-nested.current_vmptr)
+ return list_item-l2_vmcs;
+
+ return NULL;
+}
+
+/* Allocate an L0 VMCS (vmcs02) for the current L1 VMCS (vmcs12), if one
+ * does not already exist. The allocation is done in L0 memory, so to avoid
+ * denial-of-service attack by guests, we limit the number of concurrently-
+ * allocated vmcss. A well-behaving L1 will VMCLEAR unused vmcs12s and not
+ * trigger this limit.
+ */
+static const int NESTED_MAX_VMCS = 256;
+static int nested_create_current_vmcs(struct kvm_vcpu *vcpu)
+{
+ struct vmcs_list *new_l2_guest;
+ struct vmcs *l2_vmcs;
+
+ if (nested_get_current_vmcs(vcpu))
+ return 0; /* nothing to do - we already have a VMCS */
+
+ if (to_vmx(vcpu)-nested.l2_vmcs_num = NESTED_MAX_VMCS)
+ return -ENOMEM;
+
+ new_l2_guest = (struct vmcs_list *)
+ kmalloc(sizeof(struct vmcs_list), GFP_KERNEL);
+ if (!new_l2_guest)
+ return -ENOMEM;
+
+ l2_vmcs = alloc_vmcs();
+ if (!l2_vmcs) {
+ kfree(new_l2_guest);
+ return -ENOMEM;
+ }
+
+ new_l2_guest-vmcs_addr = to_vmx(vcpu)-nested.current_vmptr;
+ new_l2_guest-l2_vmcs = l2_vmcs;
+ list_add((new_l2_guest-list), (to_vmx(vcpu)-nested.l2_vmcs_list));
+ to_vmx(vcpu)-nested.l2_vmcs_num++;
+ return 0;
+}
+
+/* Free the current L2 VMCS, and remove it from l2_vmcs_list */
+static void nested_free_current_vmcs(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct vmcs_list *list_item, *n;
+
+ list_for_each_entry_safe(list_item, n, vmx-nested.l2_vmcs_list, list)
+ if (list_item-vmcs_addr == vmx-nested.current_vmptr) {
+ free_vmcs(list_item-l2_vmcs);
+ list_del((list_item-list));
+ kfree(list_item);
+ vmx-nested.l2_vmcs_num--;
+ return;
+ }
+}
+
+static void free_l1_state(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct vmcs_list *list_item, *n;
+
+ list_for_each_entry_safe(list_item, n,
+ vmx-nested.l2_vmcs_list, list) {
+ free_vmcs(list_item-l2_vmcs);
+ list_del((list_item-list));
+ kfree(list_item);
+ }
+ vmx-nested.l2_vmcs_num = 0;
+}
+
static void free_kvm_area(void)
{
int cpu;
@@ -3606,6 +3694,9 @@ static int handle_vmon(struct kvm_vcpu *
return 1;
}
+ INIT_LIST_HEAD((vmx-nested.l2_vmcs_list));
+ vmx-nested.l2_vmcs_num = 0;
+
vmx-nested.vmxon = 1;
skip_emulated_instruction(vcpu);
@@ -3650,6 +3741,8 @@ static int handle_vmoff(struct kvm_vcpu
to_vmx(vcpu)-nested.vmxon = 0;
+ free_l1_state(vcpu);
+
skip_emulated_instruction(vcpu);
return 1;
}
@@ -4402,6 +4495,8 @@ static void vmx_free_vcpu(struct kvm_vcp
struct vcpu_vmx *vmx = to_vmx(vcpu);
free_vpid(vmx);
+ if (vmx-nested.vmxon)
+ free_l1_state(vcpu);
vmx_free_vmcs(vcpu);
kfree(vmx-guest_msrs);
kvm_vcpu_uninit(vcpu);
--
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