Re: [PATCH] 2/6 i386 serialize-msr

[Zachary Amsden]

Pavel Machek wrote:

> Hi!
>
>  
>
> > i386 arch cleanup.  Introduce the serialize macro to serialize processor state.
> > Why the microcode update needs it I am not quite sure, since wrmsr() is already
> > a serializing instruction, but it is a microcode update, so I will keep the
> > semantic the same, since this could be a timing workaround.  As far as I can
> > tell, this has always been there since the original microcode update
> > source.
> >    
>
> Can we get better name, like "serialize_cpu()"?
> 									Pavel
>  

No objections to changing the name by me.  In fact, looks like serialize 
was a rather poor choice in the context of the microcode update source, 
since there are already references to lock based serialization right 
around the same code.  Updated comments as well.

Zach
i386 arch cleanup.  Introduce the serialize macro to serialize processor state.
Why the microcode update needs it I am not quite sure, since wrmsr() is already
a serializing instruction, but it is a microcode update, so I will keep the
semantic the same, since this could be a timing workaround.  As far as I can
tell, this has always been there since the original microcode update source.

Signed-off-by: Zachary Amsden <zach@xxxxxxxxxx>
Index: linux-2.6.13/arch/i386/kernel/microcode.c
===================================================================
--- linux-2.6.13.orig/arch/i386/kernel/microcode.c	2005-07-29 15:26:04.000000000 -0700
+++ linux-2.6.13/arch/i386/kernel/microcode.c	2005-07-30 10:35:27.000000000 -0700
@@ -164,7 +164,8 @@
 	}
 
 	wrmsr(MSR_IA32_UCODE_REV, 0, 0);
-	__asm__ __volatile__ ("cpuid" : : : "ax", "bx", "cx", "dx");
+	/* see 1.07.  Apprent chip bug */
+	serialize_cpu(); 
 	/* get the current revision from MSR 0x8B */
 	rdmsr(MSR_IA32_UCODE_REV, val[0], uci->rev);
 	pr_debug("microcode: collect_cpu_info : sig=0x%x, pf=0x%x, rev=0x%x\n",
@@ -377,7 +378,9 @@
 		(unsigned long) uci->mc->bits >> 16 >> 16);
 	wrmsr(MSR_IA32_UCODE_REV, 0, 0);
 
-	__asm__ __volatile__ ("cpuid" : : : "ax", "bx", "cx", "dx");
+	/* see 1.07.  Apprent chip bug */
+	serialize_cpu(); 
+
 	/* get the current revision from MSR 0x8B */
 	rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
 
Index: linux-2.6.13/include/asm-i386/processor.h
===================================================================
--- linux-2.6.13.orig/include/asm-i386/processor.h	2005-07-29 15:26:53.000000000 -0700
+++ linux-2.6.13/include/asm-i386/processor.h	2005-07-30 10:32:44.000000000 -0700
@@ -277,6 +277,11 @@
 	outb((data), 0x23); \
 } while (0)
 
+static inline void serialize_cpu(void)
+{
+	 __asm__ __volatile__ ("cpuid" : : : "ax", "bx", "cx", "dx");
+}
+
 static inline void __monitor(const void *eax, unsigned long ecx,
 		unsigned long edx)
 {