[Xen-changelog] [xen-unstable] x86/tsc: Remove incorrect assertion from cstate_restore_tsc()...

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1305548645 -3600
# Node ID 16d12acccacf09126562ca16f91bd2532bba1e9b
# Parent  87084ca76c9c24ab0306d39a70d5daa65edf09ba
x86/tsc: Remove incorrect assertion from cstate_restore_tsc()...

..fix and move to write_tsc().

Signed-off-by: Keir Fraser <keir@xxxxxxx>
---


diff -r 87084ca76c9c -r 16d12acccacf xen/arch/x86/smpboot.c
--- a/xen/arch/x86/smpboot.c    Mon May 16 13:13:41 2011 +0100
+++ b/xen/arch/x86/smpboot.c    Mon May 16 13:24:05 2011 +0100
@@ -175,7 +175,12 @@
         while ( atomic_read(&tsc_count) != ((i<<1)-1) )
             cpu_relax();
         rmb();
-        write_tsc(tsc_value);
+        /*
+         * If a CPU has been physically hotplugged, we may as well write
+         * to its TSC in spite of X86_FEATURE_TSC_RELIABLE. The platform does
+         * not sync up a new CPU's TSC for us.
+         */
+        __write_tsc(tsc_value);
         atomic_inc(&tsc_count);
     }
 }
diff -r 87084ca76c9c -r 16d12acccacf xen/arch/x86/time.c
--- a/xen/arch/x86/time.c       Mon May 16 13:13:41 2011 +0100
+++ b/xen/arch/x86/time.c       Mon May 16 13:24:05 2011 +0100
@@ -686,8 +686,6 @@
     if ( boot_cpu_has(X86_FEATURE_NONSTOP_TSC) )
         return;
 
-    ASSERT(boot_cpu_has(X86_FEATURE_TSC_RELIABLE));
-
     write_tsc(stime2tsc(read_platform_stime()));
 }
 
diff -r 87084ca76c9c -r 16d12acccacf xen/include/asm-x86/msr.h
--- a/xen/include/asm-x86/msr.h Mon May 16 13:13:41 2011 +0100
+++ b/xen/include/asm-x86/msr.h Mon May 16 13:24:05 2011 +0100
@@ -87,7 +87,13 @@
 } while(0)
 #endif
 
-#define write_tsc(val) wrmsrl(MSR_IA32_TSC, val)
+#define __write_tsc(val) wrmsrl(MSR_IA32_TSC, val)
+#define write_tsc(val) ({                                       \
+    /* Reliable TSCs are in lockstep across all CPUs. We should \
+     * never write to them. */                                  \
+    ASSERT(!boot_cpu_has(X86_FEATURE_TSC_RELIABLE));            \
+    __write_tsc(val);                                           \
+})
 
 #define write_rdtscp_aux(val) wrmsr(MSR_TSC_AUX, (val), 0)
 

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