[Xen-devel] [PATCH] VMX: Eliminate cr3 store/load vmexit when UG enabled

[Yang Zhang <yang.z.zhang@xxxxxxxxx>]

From: Yang Zhang <yang.z.zhang@xxxxxxxxx>

With the feature of unrestricted guest, there should no vmexit
be triggered when guest accesses the cr3 in non-paging mode.

Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmx.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 9ca8632..b9b5e74 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1086,7 +1086,7 @@ static void vmx_update_guest_cr(struct vcpu *v, unsigned 
int cr)
             uint32_t cr3_ctls = (CPU_BASED_CR3_LOAD_EXITING |
                                  CPU_BASED_CR3_STORE_EXITING);
             v->arch.hvm_vmx.exec_control &= ~cr3_ctls;
-            if ( !hvm_paging_enabled(v) )
+            if ( !hvm_paging_enabled(v) && !vmx_unrestricted_guest(v) )
                 v->arch.hvm_vmx.exec_control |= cr3_ctls;
 
             /* Trap CR3 updates if CR3 memory events are enabled. */
@@ -1156,7 +1156,7 @@ static void vmx_update_guest_cr(struct vcpu *v, unsigned 
int cr)
     case 3:
         if ( paging_mode_hap(v->domain) )
         {
-            if ( !hvm_paging_enabled(v) )
+            if ( !hvm_paging_enabled(v) && !vmx_unrestricted_guest(v) )
                 v->arch.hvm_vcpu.hw_cr[3] =
                     v->domain->arch.hvm_domain.params[HVM_PARAM_IDENT_PT];
             vmx_load_pdptrs(v);
@@ -2408,7 +2408,7 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
 
     hvm_invalidate_regs_fields(regs);
 
-    if ( paging_mode_hap(v->domain) && hvm_paging_enabled(v) )
+    if ( paging_mode_hap(v->domain) )
     {
         __vmread(GUEST_CR3, &v->arch.hvm_vcpu.hw_cr[3]);
         v->arch.hvm_vcpu.guest_cr[3] = v->arch.hvm_vcpu.hw_cr[3];
-- 
1.7.1


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