[Xen-devel] [PATCH v2 1/5] x86/time: Alter tsc_set_info() to return an error value

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Currently, tsc_set_info() performs no parameter checking, and an invalid
tsc_mode goes largely unnoticed.  Fix it to reject invalid tsc_modes with
-EINVAL, and update the callers to check the return value.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>

v2:
 * New
---
 xen/arch/x86/domain.c      |  4 ++--
 xen/arch/x86/domctl.c      |  8 ++++----
 xen/arch/x86/time.c        | 18 +++++++++++++-----
 xen/include/asm-x86/time.h |  7 +++----
 4 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 295b10c..245300b 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -599,8 +599,8 @@ int arch_domain_create(struct domain *d,
     else
         ASSERT_UNREACHABLE(); /* Not HVM and not PV? */
 
-    /* initialize default tsc behavior in case tools don't */
-    tsc_set_info(d, TSC_MODE_DEFAULT, 0UL, 0, 0);
+    if ( (rc = tsc_set_info(d, TSC_MODE_DEFAULT, 0UL, 0, 0)) != 0 )
+        goto fail;
 
     /* PV/PVH guests get an emulated PIT too for video BIOSes to use. */
     pit_init(d, cpu_khz);
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index aa8ad19..ed46df8 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -975,10 +975,10 @@ long arch_do_domctl(
         else
         {
             domain_pause(d);
-            tsc_set_info(d, domctl->u.tsc_info.tsc_mode,
-                         domctl->u.tsc_info.elapsed_nsec,
-                         domctl->u.tsc_info.gtsc_khz,
-                         domctl->u.tsc_info.incarnation);
+            ret = tsc_set_info(d, domctl->u.tsc_info.tsc_mode,
+                               domctl->u.tsc_info.elapsed_nsec,
+                               domctl->u.tsc_info.gtsc_khz,
+                               domctl->u.tsc_info.incarnation);
             domain_unpause(d);
         }
         break;
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 24d4c27..d80a586 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -2194,19 +2194,19 @@ void tsc_get_info(struct domain *d, uint32_t *tsc_mode,
  * only the last "sticks" and all are completed before the guest executes
  * an rdtsc instruction
  */
-void tsc_set_info(struct domain *d,
-                  uint32_t tsc_mode, uint64_t elapsed_nsec,
-                  uint32_t gtsc_khz, uint32_t incarnation)
+int tsc_set_info(struct domain *d,
+                 uint32_t tsc_mode, uint64_t elapsed_nsec,
+                 uint32_t gtsc_khz, uint32_t incarnation)
 {
     ASSERT(!is_system_domain(d));
 
     if ( is_pv_domain(d) && is_hardware_domain(d) )
     {
         d->arch.vtsc = 0;
-        return;
+        return 0;
     }
 
-    switch ( d->arch.tsc_mode = tsc_mode )
+    switch ( tsc_mode )
     {
         bool enable_tsc_scaling;
 
@@ -2253,7 +2253,13 @@ void tsc_set_info(struct domain *d,
                                   elapsed_nsec;
         }
         break;
+
+    default:
+        return -EINVAL;
     }
+
+    d->arch.tsc_mode = tsc_mode;
+
     d->arch.incarnation = incarnation + 1;
     if ( is_hvm_domain(d) )
     {
@@ -2280,6 +2286,8 @@ void tsc_set_info(struct domain *d,
     }
 
     recalculate_cpuid_policy(d);
+
+    return 0;
 }
 
 /* vtsc may incur measurable performance degradation, diagnose with this */
diff --git a/xen/include/asm-x86/time.h b/xen/include/asm-x86/time.h
index ce96ec9..6111fdc 100644
--- a/xen/include/asm-x86/time.h
+++ b/xen/include/asm-x86/time.h
@@ -60,12 +60,11 @@ uint64_t pv_soft_rdtsc(const struct vcpu *v, const struct 
cpu_user_regs *regs);
 u64 gtime_to_gtsc(struct domain *d, u64 time);
 u64 gtsc_to_gtime(struct domain *d, u64 tsc);
 
-void tsc_set_info(struct domain *d, uint32_t tsc_mode, uint64_t elapsed_nsec,
-                  uint32_t gtsc_khz, uint32_t incarnation);
-   
+int tsc_set_info(struct domain *d, uint32_t tsc_mode, uint64_t elapsed_nsec,
+                 uint32_t gtsc_khz, uint32_t incarnation);
+
 void tsc_get_info(struct domain *d, uint32_t *tsc_mode, uint64_t *elapsed_nsec,
                   uint32_t *gtsc_khz, uint32_t *incarnation);
-   
 
 void force_update_vcpu_system_time(struct vcpu *v);
 
-- 
2.1.4


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