KVM: x86: Convert TSC writes to TSC offset writes

Change svm / vmx to be the same internally and write TSC offset
instead of bare TSC in helper functions.  Isolated as a single
patch to contain code movement.

Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 5 insertions, 6 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 4fbab2469bf..d9bec5ee38b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1149,9 +1149,9 @@ static u64 guest_read_tsc(void)
  * writes 'guest_tsc' into guest's timestamp counter "register"
  * guest_tsc = host_tsc + tsc_offset ==> tsc_offset = guest_tsc - host_tsc
  */
-static void guest_write_tsc(u64 guest_tsc, u64 host_tsc)
+static void vmx_write_tsc_offset(u64 offset)
 {
-        vmcs_write64(TSC_OFFSET, guest_tsc - host_tsc);
+        vmcs_write64(TSC_OFFSET, offset);
 }
 
 /*
@@ -1255,7 +1255,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
                 break;
         case MSR_IA32_TSC:
                 rdtscll(host_tsc);
-                guest_write_tsc(data, host_tsc);
+                vmx_write_tsc_offset(data - host_tsc);
                 break;
         case MSR_IA32_CR_PAT:
                 if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
@@ -2512,7 +2512,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
 {
         u32 host_sysenter_cs, msr_low, msr_high;
         u32 junk;
-        u64 host_pat, tsc_this;
+        u64 host_pat;
         unsigned long a;
         struct desc_ptr dt;
         int i;
@@ -2653,8 +2653,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
                 vmx->vcpu.arch.cr4_guest_owned_bits |= X86_CR4_PGE;
         vmcs_writel(CR4_GUEST_HOST_MASK, ~vmx->vcpu.arch.cr4_guest_owned_bits);
 
-        tsc_this = native_read_tsc();
-        guest_write_tsc(0, tsc_this);
+        vmx_write_tsc_offset(0-native_read_tsc());
 
         return 0;
 }