nested vmx: nested TPR shadow/threshold emulation

TPR shadow/threshold feature is important to speedup the boot time
for Windows guest. Besides, it is a must feature for certain VMM.

We map virtual APIC page address and TPR threshold from L1 VMCS,
and synch it into shadow VMCS in virtual vmentry.
If TPR_BELOW_THRESHOLD VM exit is triggered by L2 guest, we
inject it into L1 VMM for handling.

Besides, this commit fixes an issue for apic access page, if L1
VMM didn't enable this feature, we need to fill zero into the
shadow VMCS.

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Committed-by: Keir Fraser <keir@xen.org>

2 files changed, 44 insertions, 3 deletions

diff --git a/xen/arch/x86/hvm/vmx/intr.c b/xen/arch/x86/hvm/vmx/intr.c
index 535248a6ac..c5c503ec2f 100644
--- a/xen/arch/x86/hvm/vmx/intr.c
+++ b/xen/arch/x86/hvm/vmx/intr.c
@@ -324,7 +324,9 @@ void vmx_intr_assist(void)
     }
 
  out:
-    if ( !cpu_has_vmx_virtual_intr_delivery && cpu_has_vmx_tpr_shadow )
+    if ( !nestedhvm_vcpu_in_guestmode(v) &&
+         !cpu_has_vmx_virtual_intr_delivery &&
+         cpu_has_vmx_tpr_shadow )
         __vmwrite(TPR_THRESHOLD, tpr_threshold);
 }
 
diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index b00581657a..7b27d2ddc7 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -471,8 +471,7 @@ void nvmx_update_exec_control(struct vcpu *v, u32 host_cntrl)
     shadow_cntrl = __n2_exec_control(v);
     pio_cntrl &= shadow_cntrl;
     /* Enforce the removed features */
-    shadow_cntrl &= ~(CPU_BASED_TPR_SHADOW
-                      | CPU_BASED_ACTIVATE_MSR_BITMAP
+    shadow_cntrl &= ~(CPU_BASED_ACTIVATE_MSR_BITMAP
                       | CPU_BASED_ACTIVATE_IO_BITMAP
                       | CPU_BASED_UNCOND_IO_EXITING);
     shadow_cntrl |= host_cntrl;
@@ -570,6 +569,38 @@ static void nvmx_update_apic_access_address(struct vcpu *v)
         __vmwrite(APIC_ACCESS_ADDR, (apic_mfn << PAGE_SHIFT));
         hvm_unmap_guest_frame(apic_va); 
     }
+    else
+        __vmwrite(APIC_ACCESS_ADDR, 0);
+}
+
+static void nvmx_update_virtual_apic_address(struct vcpu *v)
+{
+    struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
+    u64 vapic_gpfn, vapic_mfn;
+    u32 ctrl;
+    void *vapic_va;
+
+    ctrl = __n2_exec_control(v);
+    if ( ctrl & CPU_BASED_TPR_SHADOW )
+    {
+        vapic_gpfn = __get_vvmcs(nvcpu->nv_vvmcx, VIRTUAL_APIC_PAGE_ADDR) >> PAGE_SHIFT;
+        vapic_va = hvm_map_guest_frame_ro(vapic_gpfn);
+        vapic_mfn = virt_to_mfn(vapic_va);
+        __vmwrite(VIRTUAL_APIC_PAGE_ADDR, (vapic_mfn << PAGE_SHIFT));
+        hvm_unmap_guest_frame(vapic_va); 
+    }
+    else
+        __vmwrite(VIRTUAL_APIC_PAGE_ADDR, 0);
+}
+
+static void nvmx_update_tpr_threshold(struct vcpu *v)
+{
+    struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
+    u32 ctrl = __n2_exec_control(v);
+    if ( ctrl & CPU_BASED_TPR_SHADOW )
+        __vmwrite(TPR_THRESHOLD, __get_vvmcs(nvcpu->nv_vvmcx, TPR_THRESHOLD));
+    else
+        __vmwrite(TPR_THRESHOLD, 0);
 }
 
 static void __clear_current_vvmcs(struct vcpu *v)
@@ -780,6 +811,8 @@ static void load_shadow_control(struct vcpu *v)
     nvmx_update_entry_control(v);
     vmx_update_exception_bitmap(v);
     nvmx_update_apic_access_address(v);
+    nvmx_update_virtual_apic_address(v);
+    nvmx_update_tpr_threshold(v);
 }
 
 static void load_shadow_guest_state(struct vcpu *v)
@@ -1371,6 +1404,7 @@ int nvmx_msr_read_intercept(unsigned int msr, u64 *msr_content)
                CPU_BASED_ACTIVATE_MSR_BITMAP |
                CPU_BASED_PAUSE_EXITING |
                CPU_BASED_RDPMC_EXITING |
+               CPU_BASED_TPR_SHADOW |
                CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
         data = gen_vmx_msr(data, VMX_PROCBASED_CTLS_DEFAULT1, host_data);
         break;
@@ -1707,6 +1741,11 @@ int nvmx_n2_vmexit_handler(struct cpu_user_regs *regs,
         if ( ctrl & SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES )
             nvcpu->nv_vmexit_pending = 1;
         break;
+    case EXIT_REASON_TPR_BELOW_THRESHOLD:
+        ctrl = __n2_exec_control(v);
+        if ( ctrl & CPU_BASED_TPR_SHADOW )
+            nvcpu->nv_vmexit_pending = 1;
+        break;
     default:
         gdprintk(XENLOG_WARNING, "Unknown nested vmexit reason %x.\n",
                  exit_reason);