KVM: x86: Replace call-back set_tsc_khz() with a common function

Both VMX and SVM propagate virtual_tsc_khz in the same way, so this
patch removes the call-back set_tsc_khz() and replaces it with a common
function.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

5 files changed, 70 insertions, 59 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 52d1419968eb..c5a3f3d66e90 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -853,7 +853,6 @@ struct kvm_x86_ops {
 
         bool (*has_wbinvd_exit)(void);
 
-        void (*set_tsc_khz)(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale);
         u64 (*read_tsc_offset)(struct kvm_vcpu *vcpu);
         void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
 
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 65f4f1947a62..f6e49a6c9ab0 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -957,41 +957,6 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type)
         seg->base = 0;
 }
 
-static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
-{
-        u64 ratio;
-        u64 khz;
-
-        /* Guest TSC same frequency as host TSC? */
-        if (!scale) {
-                vcpu->arch.tsc_scaling_ratio = TSC_RATIO_DEFAULT;
-                return;
-        }
-
-        /* TSC scaling supported? */
-        if (!boot_cpu_has(X86_FEATURE_TSCRATEMSR)) {
-                if (user_tsc_khz > tsc_khz) {
-                        vcpu->arch.tsc_catchup = 1;
-                        vcpu->arch.tsc_always_catchup = 1;
-                } else
-                        WARN(1, "user requested TSC rate below hardware speed\n");
-                return;
-        }
-
-        khz = user_tsc_khz;
-
-        /* TSC scaling required  - calculate ratio */
-        ratio = khz << 32;
-        do_div(ratio, tsc_khz);
-
-        if (ratio == 0 || ratio & TSC_RATIO_RSVD) {
-                WARN_ONCE(1, "Invalid TSC ratio - virtual-tsc-khz=%u\n",
-                                user_tsc_khz);
-                return;
-        }
-        vcpu->arch.tsc_scaling_ratio = ratio;
-}
-
 static u64 svm_read_tsc_offset(struct kvm_vcpu *vcpu)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
@@ -4402,7 +4367,6 @@ static struct kvm_x86_ops svm_x86_ops = {
 
         .has_wbinvd_exit = svm_has_wbinvd_exit,
 
-        .set_tsc_khz = svm_set_tsc_khz,
         .read_tsc_offset = svm_read_tsc_offset,
         .write_tsc_offset = svm_write_tsc_offset,
         .adjust_tsc_offset = svm_adjust_tsc_offset,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a26ed285931b..baee46893899 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2382,22 +2382,6 @@ static u64 vmx_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
         return host_tsc + tsc_offset;
 }
 
-/*
- * Engage any workarounds for mis-matched TSC rates.  Currently limited to
- * software catchup for faster rates on slower CPUs.
- */
-static void vmx_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
-{
-        if (!scale)
-                return;
-
-        if (user_tsc_khz > tsc_khz) {
-                vcpu->arch.tsc_catchup = 1;
-                vcpu->arch.tsc_always_catchup = 1;
-        } else
-                WARN(1, "user requested TSC rate below hardware speed\n");
-}
-
 static u64 vmx_read_tsc_offset(struct kvm_vcpu *vcpu)
 {
         return vmcs_read64(TSC_OFFSET);
@@ -10826,7 +10810,6 @@ static struct kvm_x86_ops vmx_x86_ops = {
 
         .has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,
 
-        .set_tsc_khz = vmx_set_tsc_khz,
         .read_tsc_offset = vmx_read_tsc_offset,
         .write_tsc_offset = vmx_write_tsc_offset,
         .adjust_tsc_offset = vmx_adjust_tsc_offset,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1473e64cb744..c314e8d22a67 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1253,7 +1253,43 @@ static u32 adjust_tsc_khz(u32 khz, s32 ppm)
         return v;
 }
 
-static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
+static int set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
+{
+        u64 ratio;
+
+        /* Guest TSC same frequency as host TSC? */
+        if (!scale) {
+                vcpu->arch.tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
+                return 0;
+        }
+
+        /* TSC scaling supported? */
+        if (!kvm_has_tsc_control) {
+                if (user_tsc_khz > tsc_khz) {
+                        vcpu->arch.tsc_catchup = 1;
+                        vcpu->arch.tsc_always_catchup = 1;
+                        return 0;
+                } else {
+                        WARN(1, "user requested TSC rate below hardware speed\n");
+                        return -1;
+                }
+        }
+
+        /* TSC scaling required  - calculate ratio */
+        ratio = mul_u64_u32_div(1ULL << kvm_tsc_scaling_ratio_frac_bits,
+                                user_tsc_khz, tsc_khz);
+
+        if (ratio == 0 || ratio >= kvm_max_tsc_scaling_ratio) {
+                WARN_ONCE(1, "Invalid TSC scaling ratio - virtual-tsc-khz=%u\n",
+                          user_tsc_khz);
+                return -1;
+        }
+
+        vcpu->arch.tsc_scaling_ratio = ratio;
+        return 0;
+}
+
+static int kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
 {
         u32 thresh_lo, thresh_hi;
         int use_scaling = 0;
@@ -1262,7 +1298,7 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
         if (this_tsc_khz == 0) {
                 /* set tsc_scaling_ratio to a safe value */
                 vcpu->arch.tsc_scaling_ratio = kvm_default_tsc_scaling_ratio;
-                return;
+                return -1;
         }
 
         /* Compute a scale to convert nanoseconds in TSC cycles */
@@ -1283,7 +1319,7 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
                 pr_debug("kvm: requested TSC rate %u falls outside tolerance [%u,%u]\n", this_tsc_khz, thresh_lo, thresh_hi);
                 use_scaling = 1;
         }
-        kvm_x86_ops->set_tsc_khz(vcpu, this_tsc_khz, use_scaling);
+        return set_tsc_khz(vcpu, this_tsc_khz, use_scaling);
 }
 
 static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
@@ -3353,9 +3389,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 if (user_tsc_khz == 0)
                         user_tsc_khz = tsc_khz;
 
-                kvm_set_tsc_khz(vcpu, user_tsc_khz);
+                if (!kvm_set_tsc_khz(vcpu, user_tsc_khz))
+                        r = 0;
 
-                r = 0;
                 goto out;
         }
         case KVM_GET_TSC_KHZ: {
diff --git a/include/linux/math64.h b/include/linux/math64.h
index 44282ec7b682..6e8b5b270ffe 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -214,4 +214,33 @@ static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift)
 
 #endif
 
+#ifndef mul_u64_u32_div
+static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
+{
+        union {
+                u64 ll;
+                struct {
+#ifdef __BIG_ENDIAN
+                        u32 high, low;
+#else
+                        u32 low, high;
+#endif
+                } l;
+        } u, rl, rh;
+
+        u.ll = a;
+        rl.ll = (u64)u.l.low * mul;
+        rh.ll = (u64)u.l.high * mul + rl.l.high;
+
+        /* Bits 32-63 of the result will be in rh.l.low. */
+        rl.l.high = do_div(rh.ll, divisor);
+
+        /* Bits 0-31 of the result will be in rl.l.low. */
+        do_div(rl.ll, divisor);
+
+        rl.l.high = rh.l.low;
+        return rl.ll;
+}
+#endif /* mul_u64_u32_div */
+
 #endif /* _LINUX_MATH64_H */