[Xen-devel] [PATCH] nested vmx: nested TPR shadow/threshold emulation

[Dongxiao Xu <dongxiao.xu@xxxxxxxxx>]

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@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/intr.c |    4 +++-
 xen/arch/x86/hvm/vmx/vvmx.c |   43 +++++++++++++++++++++++++++++++++++++++++--
 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 535248a..c5c503e 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 b005816..7b27d2d 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);
-- 
1.7.1


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