[PATCH v3 09/13] x86/hvm: Replace architecture TSC scaling by a common function

[Haozhong Zhang <haozhong.zhang@intel.com>]

This patch implements a common function hvm_scale_tsc() to scale TSC by
using TSC scaling information collected by architecture code.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com> (except the mul64 part)
---
Changes in v3:
 (addressing Boris Ostrovsky's comments)
 * Remove unnecessary assertions in hvm_scale_tsc().
 * Move math64 stuffs to a standalone patch and state their origination.

 xen/arch/x86/hvm/hvm.c        | 15 +++++++++++++--
 xen/arch/x86/hvm/svm/svm.c    | 12 ------------
 xen/arch/x86/time.c           |  2 +-
 xen/include/asm-x86/hvm/hvm.h |  3 +--
 4 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 3bf99b1..a900b4c 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -302,6 +302,17 @@ int hvm_set_guest_pat(struct vcpu *v, u64 guest_pat)
     return 1;
 }
 
+u64 hvm_scale_tsc(const struct vcpu *v, u64 tsc)
+{
+    u64 ratio = v->arch.hvm_vcpu.tsc_scaling_ratio;
+
+    if ( !hvm_funcs.tsc_scaling_supported ||
+         ratio == hvm_funcs.default_tsc_scaling_ratio )
+        return tsc;
+
+    return mul_u64_u64_shr(tsc, ratio, hvm_funcs.tsc_scaling_ratio_frac_bits);
+}
+
 bool_t hvm_validate_tsc_scaling_ratio(uint32_t gtsc_khz)
 {
     u64 ratio;
@@ -352,7 +363,7 @@ void hvm_set_guest_tsc_fixed(struct vcpu *v, u64 guest_tsc, u64 at_tsc)
     {
         tsc = at_tsc ?: rdtsc();
         if ( cpu_has_tsc_ratio )
-            tsc = hvm_funcs.scale_tsc(v, tsc);
+            tsc = hvm_scale_tsc(v, tsc);
     }
 
     delta_tsc = guest_tsc - tsc;
@@ -384,7 +395,7 @@ u64 hvm_get_guest_tsc_fixed(struct vcpu *v, uint64_t at_tsc)
     {
         tsc = at_tsc ?: rdtsc();
         if ( cpu_has_tsc_ratio )
-            tsc = hvm_funcs.scale_tsc(v, tsc);
+            tsc = hvm_scale_tsc(v, tsc);
     }
 
     return tsc + v->arch.hvm_vcpu.cache_tsc_offset;
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index b58f1e8..71538c8 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -804,16 +804,6 @@ static uint64_t scale_tsc(uint64_t host_tsc, uint64_t ratio)
     return scaled_host_tsc;
 }
 
-static uint64_t svm_scale_tsc(struct vcpu *v, uint64_t tsc)
-{
-    struct domain *d = v->domain;
-
-    if ( !cpu_has_tsc_ratio || d->arch.vtsc )
-        return tsc;
-
-    return scale_tsc(tsc, v->arch.hvm_vcpu.tsc_scaling_ratio);
-}
-
 static uint64_t svm_get_tsc_offset(uint64_t host_tsc, uint64_t guest_tsc,
     uint64_t ratio)
 {
@@ -2276,8 +2266,6 @@ static struct hvm_function_table __initdata svm_function_table = {
     .nhvm_intr_blocked = nsvm_intr_blocked,
     .nhvm_hap_walk_L1_p2m = nsvm_hap_walk_L1_p2m,
 
-    .scale_tsc            = svm_scale_tsc,
-
     .default_tsc_scaling_ratio   = DEFAULT_TSC_RATIO,
     .max_tsc_scaling_ratio       = ~TSC_RATIO_RSVD_BITS,
     .tsc_scaling_ratio_frac_bits = 32,
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index e69d9de..8d391e0 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -817,7 +817,7 @@ static void __update_vcpu_system_time(struct vcpu *v, int force)
     {
         if ( has_hvm_container_domain(d) && cpu_has_tsc_ratio )
         {
-            tsc_stamp            = hvm_funcs.scale_tsc(v, t->local_tsc_stamp);
+            tsc_stamp            = hvm_scale_tsc(v, t->local_tsc_stamp);
             _u.tsc_to_system_mul = d->arch.vtsc_to_ns.mul_frac;
             _u.tsc_shift         = d->arch.vtsc_to_ns.shift;
         }
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 6b49da8..05894ee 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -225,8 +225,6 @@ struct hvm_function_table {
     bool_t (*altp2m_vcpu_emulate_ve)(struct vcpu *v);
     int (*altp2m_vcpu_emulate_vmfunc)(struct cpu_user_regs *regs);
 
-    uint64_t (*scale_tsc)(struct vcpu *v, uint64_t tsc);
-
     /* Architecture function to setup TSC scaling ratio */
     void (*setup_tsc_scaling)(struct vcpu *v);
 };
@@ -264,6 +262,7 @@ void hvm_set_guest_tsc_fixed(struct vcpu *v, u64 guest_tsc, u64 at_tsc);
 u64 hvm_get_guest_tsc_fixed(struct vcpu *v, u64 at_tsc);
 #define hvm_get_guest_tsc(v) hvm_get_guest_tsc_fixed(v, 0)
 
+u64 hvm_scale_tsc(const struct vcpu *v, u64 tsc);
 bool_t hvm_validate_tsc_scaling_ratio(uint32_t gtsc_khz);
 void hvm_setup_tsc_scaling(struct vcpu *v);
 
-- 
2.4.8