Allocate a shadow vmcs used by the processor to shadow part of the fields
stored in the software defined VMCS12 (let L1 access fields without causing
exits). Note we keep a shadow vmcs only for the current vmcs12. Once a vmcs12
becomes non-current, its shadow vmcs is released.
Signed-off-by: Abel Gordon <abelg@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
--- .before/arch/x86/kvm/vmx.c 2013-04-18 13:31:34.000000000 +0300
+++ .after/arch/x86/kvm/vmx.c 2013-04-18 13:31:34.000000000 +0300
@@ -355,6 +355,7 @@ struct nested_vmx {
/* The host-usable pointer to the above */
struct page *current_vmcs12_page;
struct vmcs12 *current_vmcs12;
+ struct vmcs *current_shadow_vmcs;
/* vmcs02_list cache of VMCSs recently used to run L2 guests */
struct list_head vmcs02_pool;
@@ -5527,6 +5528,7 @@ static int handle_vmon(struct kvm_vcpu *
{
struct kvm_segment cs;
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ struct vmcs *shadow_vmcs;
/* The Intel VMX Instruction Reference lists a bunch of bits that
* are prerequisite to running VMXON, most notably cr4.VMXE must be
@@ -5555,6 +5557,16 @@ static int handle_vmon(struct kvm_vcpu *
skip_emulated_instruction(vcpu);
return 1;
}
+ if (enable_shadow_vmcs) {
+ shadow_vmcs = alloc_vmcs();
+ if (!shadow_vmcs)
+ return -ENOMEM;
+ /* mark vmcs as shadow */
+ shadow_vmcs->revision_id |= (1u << 31);
+ /* init shadow vmcs */
+ vmcs_clear(shadow_vmcs);
+ vmx->nested.current_shadow_vmcs = shadow_vmcs;
+ }
INIT_LIST_HEAD(&(vmx->nested.vmcs02_pool));
vmx->nested.vmcs02_num = 0;
--
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