[Xen-devel] [PATCH v4 04/10] x86/hvm: Collect information of TSC scaling ratio

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

Both VMX TSC scaling and SVM TSC ratio use the 64-bit TSC scaling ratio,
but the number of fractional bits of the ratio is different between VMX
and SVM. This patch adds the architecture code to collect the number of
fractional bits and other related information into fields of struct
hvm_function_table so that they can be used in the common code.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
Changes in v4:
 (addressing Jan Beulich's comments in v3 patch 12)
 * Set TSC scaling parameters in hvm_funcs conditionally.
 * Remove TSC scaling parameter tsc_scaling_supported in hvm_funcs which
   can be derived from other parameters.
 (code cleanup)
 * Merge with v3 patch 11 "x86/hvm: Detect TSC scaling through hvm_funcs"
   whose work can be done early in this patch.

 xen/arch/x86/hvm/hvm.c        |  4 ++--
 xen/arch/x86/hvm/svm/svm.c    | 10 ++++++++--
 xen/arch/x86/time.c           |  9 ++++-----
 xen/include/asm-x86/hvm/hvm.h | 14 ++++++++++++++
 4 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 3648a44..6d30d8b 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -314,7 +314,7 @@ void hvm_set_guest_tsc_fixed(struct vcpu *v, u64 guest_tsc, 
u64 at_tsc)
     else
     {
         tsc = at_tsc ?: rdtsc();
-        if ( cpu_has_tsc_ratio )
+        if ( hvm_tsc_scaling_supported )
             tsc = hvm_funcs.scale_tsc(v, tsc);
     }
 
@@ -346,7 +346,7 @@ u64 hvm_get_guest_tsc_fixed(struct vcpu *v, uint64_t at_tsc)
     else
     {
         tsc = at_tsc ?: rdtsc();
-        if ( cpu_has_tsc_ratio )
+        if ( hvm_tsc_scaling_supported )
             tsc = hvm_funcs.scale_tsc(v, tsc);
     }
 
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 953e0b5..8b316a0 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1450,6 +1450,14 @@ const struct hvm_function_table * __init start_svm(void)
     if ( !cpu_has_svm_nrips )
         clear_bit(SVM_FEATURE_DECODEASSISTS, &svm_feature_flags);
 
+    if ( cpu_has_tsc_ratio )
+    {
+        svm_function_table.default_tsc_scaling_ratio = DEFAULT_TSC_RATIO;
+        svm_function_table.max_tsc_scaling_ratio = ~TSC_RATIO_RSVD_BITS;
+        svm_function_table.tsc_scaling_ratio_frac_bits = 32;
+        svm_function_table.scale_tsc = svm_scale_tsc;
+    }
+
 #define P(p,s) if ( p ) { printk(" - %s\n", s); printed = 1; }
     P(cpu_has_svm_npt, "Nested Page Tables (NPT)");
     P(cpu_has_svm_lbrv, "Last Branch Record (LBR) Virtualisation");
@@ -2269,8 +2277,6 @@ static struct hvm_function_table __initdata 
svm_function_table = {
     .nhvm_vmcx_hap_enabled = nsvm_vmcb_hap_enabled,
     .nhvm_intr_blocked = nsvm_intr_blocked,
     .nhvm_hap_walk_L1_p2m = nsvm_hap_walk_L1_p2m,
-
-    .scale_tsc            = svm_scale_tsc,
 };
 
 void svm_vmexit_handler(struct cpu_user_regs *regs)
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 988403a..a243bc3 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -37,7 +37,6 @@
 #include <asm/hpet.h>
 #include <io_ports.h>
 #include <asm/setup.h> /* for early_time_init */
-#include <asm/hvm/svm/svm.h> /* for cpu_has_tsc_ratio */
 #include <public/arch-x86/cpuid.h>
 
 /* opt_clocksource: Force clocksource to one of: pit, hpet, acpi. */
@@ -815,7 +814,7 @@ static void __update_vcpu_system_time(struct vcpu *v, int 
force)
     }
     else
     {
-        if ( has_hvm_container_domain(d) && cpu_has_tsc_ratio )
+        if ( has_hvm_container_domain(d) && hvm_tsc_scaling_supported )
         {
             tsc_stamp            = hvm_funcs.scale_tsc(v, t->local_tsc_stamp);
             _u.tsc_to_system_mul = d->arch.vtsc_to_ns.mul_frac;
@@ -1758,7 +1757,7 @@ void tsc_get_info(struct domain *d, uint32_t *tsc_mode,
                   uint32_t *incarnation)
 {
     bool_t enable_tsc_scaling = has_hvm_container_domain(d) &&
-                                cpu_has_tsc_ratio && !d->arch.vtsc;
+                                hvm_tsc_scaling_supported && !d->arch.vtsc;
 
     *incarnation = d->arch.incarnation;
     *tsc_mode = d->arch.tsc_mode;
@@ -1865,7 +1864,7 @@ void tsc_set_info(struct domain *d,
          */
         if ( tsc_mode == TSC_MODE_DEFAULT && host_tsc_is_safe() &&
              (has_hvm_container_domain(d) ?
-              d->arch.tsc_khz == cpu_khz || cpu_has_tsc_ratio :
+              d->arch.tsc_khz == cpu_khz || hvm_tsc_scaling_supported :
               incarnation == 0) )
         {
     case TSC_MODE_NEVER_EMULATE:
@@ -1879,7 +1878,7 @@ void tsc_set_info(struct domain *d,
         d->arch.vtsc = !boot_cpu_has(X86_FEATURE_RDTSCP) ||
                        !host_tsc_is_safe();
         enable_tsc_scaling = has_hvm_container_domain(d) &&
-                             cpu_has_tsc_ratio && !d->arch.vtsc;
+                             hvm_tsc_scaling_supported && !d->arch.vtsc;
         d->arch.tsc_khz = (enable_tsc_scaling && gtsc_khz) ? gtsc_khz : 
cpu_khz;
         set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000 );
         d->arch.ns_to_vtsc = scale_reciprocal(d->arch.vtsc_to_ns);
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index a87224b..79ea59e 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -100,6 +100,17 @@ struct hvm_function_table {
     unsigned int hap_capabilities;
 
     /*
+     * Parameters of hardware-assisted TSC scaling, which are valid only when
+     * the hardware feature is available.
+     */
+    /* number of bits of the fractional part of TSC scaling ratio */
+    uint8_t  tsc_scaling_ratio_frac_bits;
+    /* default TSC scaling ratio (no scaling) */
+    uint64_t default_tsc_scaling_ratio;
+    /* maximum-allowed TSC scaling ratio */
+    uint64_t max_tsc_scaling_ratio;
+
+    /*
      * Initialise/destroy HVM domain/vcpu resources
      */
     int  (*domain_initialise)(struct domain *d);
@@ -213,6 +224,7 @@ struct hvm_function_table {
     bool_t (*altp2m_vcpu_emulate_ve)(struct vcpu *v);
     int (*altp2m_vcpu_emulate_vmfunc)(struct cpu_user_regs *regs);
 
+    /* Valid only when hardware-assisted TSC scaling is available */
     uint64_t (*scale_tsc)(const struct vcpu *v, uint64_t tsc);
 };
 
@@ -249,6 +261,8 @@ 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)
 
+#define hvm_tsc_scaling_supported (!!hvm_funcs.default_tsc_scaling_ratio)
+
 int hvm_set_mode(struct vcpu *v, int mode);
 void hvm_init_guest_time(struct domain *d);
 void hvm_set_guest_time(struct vcpu *v, u64 guest_time);
-- 
2.7.0


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