[Xen-changelog] [xen master] x86/time: use correct guest TSC frequency in tsc_set_info()

[patchbot@xxxxxxx]

commit 0a449aa43d88164789b3f60ed3bbd64dae897da8
Author:     Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
AuthorDate: Fri Jan 8 10:48:10 2016 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jan 8 10:48:10 2016 +0100

    x86/time: use correct guest TSC frequency in tsc_set_info()
    
    When TSC_MODE_PVRDTSCP is used for a HVM container and TSC scaling is
    available, use the non-zero value of argument gtsc_khz of tsc_set_info()
    as the guest TSC frequency rather than using the host TSC
    frequency. Otherwise, TSC scaling will not be able get the correct ratio
    between the host and guest TSC frequencies.
    
    Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
    Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 xen/arch/x86/time.c          |    9 +++++++--
 xen/include/asm-x86/domain.h |    9 ++++++---
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index b5223cf..ee4d755 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -1838,6 +1838,8 @@ void tsc_set_info(struct domain *d,
 
     switch ( d->arch.tsc_mode = tsc_mode )
     {
+        bool_t enable_tsc_scaling;
+
     case TSC_MODE_DEFAULT:
     case TSC_MODE_ALWAYS_EMULATE:
         d->arch.vtsc_offset = get_s_time() - elapsed_nsec;
@@ -1864,7 +1866,9 @@ void tsc_set_info(struct domain *d,
     case TSC_MODE_PVRDTSCP:
         d->arch.vtsc = !boot_cpu_has(X86_FEATURE_RDTSCP) ||
                        !host_tsc_is_safe();
-        d->arch.tsc_khz = cpu_khz;
+        enable_tsc_scaling = has_hvm_container_domain(d) &&
+                             cpu_has_tsc_ratio && !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);
         if ( d->arch.vtsc )
@@ -1872,7 +1876,8 @@ void tsc_set_info(struct domain *d,
         else {
             /* when using native TSC, offset is nsec relative to power-on
              * of physical machine */
-            d->arch.vtsc_offset = scale_delta(rdtsc(), &d->arch.vtsc_to_ns) -
+            d->arch.vtsc_offset = scale_delta(rdtsc(),
+                                              &this_cpu(cpu_time).tsc_scale) -
                                   elapsed_nsec;
         }
         break;
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index e8f7037..405adef 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -347,9 +347,12 @@ struct arch_domain
     s_time_t vtsc_last;      /* previous TSC value (guarantee monotonicity) */
     spinlock_t vtsc_lock;
     uint64_t vtsc_offset;    /* adjustment for save/restore/migrate */
-    uint32_t tsc_khz;        /* cached khz for certain emulated cases */
-    struct time_scale vtsc_to_ns; /* scaling for certain emulated cases */
-    struct time_scale ns_to_vtsc; /* scaling for certain emulated cases */
+    uint32_t tsc_khz;        /* cached guest khz for certain emulated or
+                                hardware TSC scaling cases */
+    struct time_scale vtsc_to_ns; /* scaling for certain emulated or
+                                     hardware TSC scaling cases */
+    struct time_scale ns_to_vtsc; /* scaling for certain emulated or
+                                     hardware TSC scaling cases */
     uint32_t incarnation;    /* incremented every restore or live migrate
                                 (possibly other cases in the future */
 #if !defined(NDEBUG) || defined(PERF_COUNTERS)
--
generated by git-patchbot for /home/xen/git/xen.git#master

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