[Xen-devel] [RFC, PATCH 17/24] i386 Vmi msr patch

[Zachary Amsden <zach@xxxxxxxxxx>]

Fairly straightforward code motion of MSR / TSC / PMC accessors
to the sub-arch level.  Note that rdmsr/wrmsr_safe functions are
not moved; Linux relies on the fault behavior here in the event
that certain MSRs are not supported on hardware, and combining
this with a VMI wrapper is overly complicated.  The instructions
are virtualizable with trap and emulate, not on critical code
paths, and only used as part of the MSR /proc device, which is
highly sketchy to use inside a virtual machine, but must be
allowed as part of the compile, since it is useful on native.

Signed-off-by: Zachary Amsden <zach@xxxxxxxxxx>

Index: linux-2.6.16-rc5/include/asm-i386/msr.h
===================================================================
--- linux-2.6.16-rc5.orig/include/asm-i386/msr.h        2006-03-08 
10:31:10.000000000 -0800
+++ linux-2.6.16-rc5/include/asm-i386/msr.h     2006-03-08 10:32:07.000000000 
-0800
@@ -1,22 +1,14 @@
 #ifndef __ASM_MSR_H
 #define __ASM_MSR_H
 
+#include <mach_msr.h>
+
 /*
  * Access to machine-specific registers (available on 586 and better only)
  * Note: the rd* operations modify the parameters directly (without using
  * pointer indirection), this allows gcc to optimize better
  */
 
-#define rdmsr(msr,val1,val2) \
-       __asm__ __volatile__("rdmsr" \
-                         : "=a" (val1), "=d" (val2) \
-                         : "c" (msr))
-
-#define wrmsr(msr,val1,val2) \
-       __asm__ __volatile__("wrmsr" \
-                         : /* no outputs */ \
-                         : "c" (msr), "a" (val1), "d" (val2))
-
 #define rdmsrl(msr,val) do { \
        unsigned long l__,h__; \
        rdmsr (msr, l__, h__);  \
@@ -62,22 +54,6 @@ static inline void wrmsrl (unsigned long
                     : "c" (msr), "i" (-EFAULT));\
        ret__; })
 
-#define rdtsc(low,high) \
-     __asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high))
-
-#define rdtscl(low) \
-     __asm__ __volatile__("rdtsc" : "=a" (low) : : "edx")
-
-#define rdtscll(val) \
-     __asm__ __volatile__("rdtsc" : "=A" (val))
-
-#define write_tsc(val1,val2) wrmsr(0x10, val1, val2)
-
-#define rdpmc(counter,low,high) \
-     __asm__ __volatile__("rdpmc" \
-                         : "=a" (low), "=d" (high) \
-                         : "c" (counter))
-
 /* symbolic names for some interesting MSRs */
 /* Intel defined MSRs. */
 #define MSR_IA32_P5_MC_ADDR            0
Index: linux-2.6.16-rc5/include/asm-i386/mach-vmi/mach_msr.h
===================================================================
--- linux-2.6.16-rc5.orig/include/asm-i386/mach-vmi/mach_msr.h  2006-03-08 
10:32:07.000000000 -0800
+++ linux-2.6.16-rc5/include/asm-i386/mach-vmi/mach_msr.h       2006-03-08 
10:32:30.000000000 -0800
@@ -0,0 +1,79 @@
+#ifndef MACH_MSR_H
+#define MACH_MSR_H
+
+#include <vmi.h>
+
+static inline u64 vmi_rdmsr(const u32 msr)
+{
+       u64 ret;
+       vmi_wrap_call(
+               RDMSR, "rdmsr",
+               VMI_OREG64 (ret),
+               1, "c" (msr),
+               VMI_CLOBBER(TWO_RETURNS));
+       return ret;
+}
+
+#define rdmsr(msr,val1,val2) \
+do { \
+       u64 _val = vmi_rdmsr(msr); \
+       val1 = (u32)_val; \
+       val2 = (u32)(_val >> 32); \
+} while (0)
+
+static inline void wrmsr(const u32 msr, const u32 valLo, const u32 valHi)
+{
+       vmi_wrap_call(
+               WRMSR, "wrmsr",
+               VMI_NO_OUTPUT,
+               3, XCONC("a"(valLo), "d"(valHi), "c"(msr)),
+               VMI_CLOBBER_EXTENDED(ZERO_RETURNS, "memory"));
+}
+
+static inline u64 vmi_rdtsc(void)
+{
+       u64 ret;
+       vmi_wrap_call(
+               RDTSC, "rdtsc",
+               VMI_OREG64 (ret),
+               0, VMI_NO_INPUT,
+               VMI_CLOBBER(TWO_RETURNS));
+       return ret;
+}
+
+#define rdtsc(low,high) \
+do { \
+       u64 _val = vmi_rdtsc(); \
+       low = (u32)_val; \
+       high = (u32)(_val >> 32); \
+} while (0)
+
+#define rdtscl(low) \
+do { \
+       u64 _val = vmi_rdtsc(); \
+       low = (u32)_val; \
+} while (0)
+
+#define rdtscll(val) do { val = vmi_rdtsc(); } while (0)
+
+#define write_tsc(val1,val2) wrmsr(0x10, val1, val2)
+
+static inline u64 vmi_rdpmc(const u32 counter)
+{
+       u64 ret;
+       vmi_wrap_call(
+               RDPMC, "rdpmc",
+               VMI_OREG64 (ret),
+               1, "c" (counter),
+               VMI_CLOBBER(TWO_RETURNS));
+       return ret;
+}
+
+#define rdpmc(counter,val1,val2) \
+do { \
+       u64 _val = vmi_rdpmc(counter); \
+       val1 = (u32)_val; \
+       val2 = (u32)(_val >> 32); \
+} while (0)
+
+#endif
Index: linux-2.6.16-rc5/include/asm-i386/mach-default/mach_msr.h
===================================================================
--- linux-2.6.16-rc5.orig/include/asm-i386/mach-default/mach_msr.h      
2006-03-08 10:32:07.000000000 -0800
+++ linux-2.6.16-rc5/include/asm-i386/mach-default/mach_msr.h   2006-03-08 
10:32:07.000000000 -0800
@@ -0,0 +1,30 @@
+#ifndef MACH_MSR_H
+#define MACH_MSR_H
+
+#define rdmsr(msr,val1,val2) \
+       __asm__ __volatile__("rdmsr" \
+                         : "=a" (val1), "=d" (val2) \
+                         : "c" (msr))
+
+#define wrmsr(msr,val1,val2) \
+       __asm__ __volatile__("wrmsr" \
+                         : /* no outputs */ \
+                         : "c" (msr), "a" (val1), "d" (val2))
+
+#define rdtsc(low,high) \
+     __asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high))
+
+#define rdtscl(low) \
+     __asm__ __volatile__("rdtsc" : "=a" (low) : : "edx")
+
+#define rdtscll(val) \
+     __asm__ __volatile__("rdtsc" : "=A" (val))
+
+#define write_tsc(val1,val2) wrmsr(0x10, val1, val2)
+
+#define rdpmc(counter,low,high) \
+     __asm__ __volatile__("rdpmc" \
+                         : "=a" (low), "=d" (high) \
+                         : "c" (counter))
+
+#endif

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