x86: Implement TSC adjust feature for HVM guest

IA32_TSC_ADJUST MSR is maintained separately for each logical
processor. A logical processor maintains and uses the IA32_TSC_ADJUST
MSR as follows:
1). On RESET, the value of the IA32_TSC_ADJUST MSR is 0;
2). If an execution of WRMSR to the IA32_TIME_STAMP_COUNTER MSR adds
    (or subtracts) value X from the TSC, the logical processor also
    adds (or subtracts) value X from the IA32_TSC_ADJUST MSR;
3). If an execution of WRMSR to the IA32_TSC_ADJUST MSR adds (or
    subtracts) value X from that MSR, the logical processor also adds
    (or subtracts) value X from the TSC.

This patch provides tsc adjust support for hvm guest, with it guest OS
would be happy when sync tsc.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Committed-by: Jan Beulich <jbeulich@suse.com>

1 files changed, 29 insertions, 1 deletions

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 0929a098f7..52ba47ca28 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -237,6 +237,7 @@ int hvm_set_guest_pat(struct vcpu *v, u64 guest_pat)
 void hvm_set_guest_tsc(struct vcpu *v, u64 guest_tsc)
 {
     uint64_t tsc;
+    uint64_t delta_tsc;
 
     if ( v->domain->arch.vtsc )
     {
@@ -248,10 +249,22 @@ void hvm_set_guest_tsc(struct vcpu *v, u64 guest_tsc)
         rdtscll(tsc);
     }
 
-    v->arch.hvm_vcpu.cache_tsc_offset = guest_tsc - tsc;
+    delta_tsc = guest_tsc - tsc;
+    v->arch.hvm_vcpu.msr_tsc_adjust += delta_tsc
+                          - v->arch.hvm_vcpu.cache_tsc_offset;
+    v->arch.hvm_vcpu.cache_tsc_offset = delta_tsc;
+
     hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset);
 }
 
+void hvm_set_guest_tsc_adjust(struct vcpu *v, u64 tsc_adjust)
+{
+    v->arch.hvm_vcpu.cache_tsc_offset += tsc_adjust
+                            - v->arch.hvm_vcpu.msr_tsc_adjust;
+    hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset);
+    v->arch.hvm_vcpu.msr_tsc_adjust = tsc_adjust;
+}
+
 u64 hvm_get_guest_tsc(struct vcpu *v)
 {
     uint64_t tsc;
@@ -270,6 +283,11 @@ u64 hvm_get_guest_tsc(struct vcpu *v)
     return tsc + v->arch.hvm_vcpu.cache_tsc_offset;
 }
 
+u64 hvm_get_guest_tsc_adjust(struct vcpu *v)
+{
+    return v->arch.hvm_vcpu.msr_tsc_adjust;
+}
+
 void hvm_migrate_timers(struct vcpu *v)
 {
     rtc_migrate_timers(v);
@@ -2769,6 +2787,10 @@ int hvm_msr_read_intercept(unsigned int msr, uint64_t *msr_content)
         *msr_content = hvm_get_guest_tsc(v);
         break;
 
+    case MSR_IA32_TSC_ADJUST:
+        *msr_content = hvm_get_guest_tsc_adjust(v);
+        break;
+
     case MSR_TSC_AUX:
         *msr_content = hvm_msr_tsc_aux(v);
         break;
@@ -2882,6 +2904,10 @@ int hvm_msr_write_intercept(unsigned int msr, uint64_t msr_content)
         hvm_set_guest_tsc(v, msr_content);
         break;
 
+    case MSR_IA32_TSC_ADJUST:
+        hvm_set_guest_tsc_adjust(v, msr_content);
+        break;
+
     case MSR_TSC_AUX:
         v->arch.hvm_vcpu.msr_tsc_aux = (uint32_t)msr_content;
         if ( cpu_has_rdtscp
@@ -3429,6 +3455,8 @@ void hvm_vcpu_reset_state(struct vcpu *v, uint16_t cs, uint16_t ip)
         v->domain->vcpu[0]->arch.hvm_vcpu.cache_tsc_offset;
     hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset);
 
+    v->arch.hvm_vcpu.msr_tsc_adjust = 0;
+
     paging_update_paging_modes(v);
 
     v->arch.flags |= TF_kernel_mode;