[Xen-devel] [PATCH 11/13] vmx: Use scaled host TSC to calculate TSC offset

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

If VMX TSC scaling is enabled and no TSC emulation is used,
vmx_set_tsc_offset() will calculate the TSC offset by substracting the
scaled host TSC from the current guest TSC.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmx.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 454440e..163974d 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1102,11 +1102,26 @@ static void vmx_handle_cd(struct vcpu *v, unsigned long 
value)
 
 static void vmx_set_tsc_offset(struct vcpu *v, u64 offset, u64 at_tsc)
 {
+    uint64_t host_tsc, guest_tsc;
+    struct domain *d = v->domain;
+
+    guest_tsc = hvm_get_guest_tsc_fixed(v, at_tsc);
+
+    if ( cpu_has_vmx_tsc_scaling && !d->arch.vtsc )
+    {
+        host_tsc = at_tsc ? at_tsc : rdtsc();
+        offset = guest_tsc - hvm_scale_tsc(v, host_tsc);
+    }
+
     vmx_vmcs_enter(v);
 
+    if ( !nestedhvm_enabled(d) )
+        goto out;
+
     if ( nestedhvm_vcpu_in_guestmode(v) )
         offset += nvmx_get_tsc_offset(v);
 
+out:
     __vmwrite(TSC_OFFSET, offset);
     vmx_vmcs_exit(v);
 }
-- 
2.4.8


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel