[PATCH/RFC] Per-architecture hypercall definitions

[PATCH/RFC] Per-architecture hypercall definitions

[Christian Borntraeger]

Currently kvm provides hypercalls only for x86* architectures. To
provide hypercall infrastructure for other kvm architectures I split
kvm_para.h into a generic header file and architecture specific
definitions.
Currently there are definitions for s390 (experimental, ABI not final,
and I still have to find out how to get an assigned diagnose number)
and x86. I already made the split using the common x86 architecture
folder that will hit 2.6.24-rc soon. 

One point for discussion:

i386 only supports up to 4 parameters. On s390 I coded definitions for
up to 6 parameters. Are we going to limit kvm to 4 parameters?

Besides the experimental state of the s390 ABI, the patch should be 
mergable as soon as the x86 merge is finished.

Feedback is welcome.

Christian

---
 include/asm-s390/kvm_para.h |  128 ++++++++++++++++++++++++++++++++++++++++++++
 include/asm-x86/kvm_para.h  |  110 +++++++++++++++++++++++++++++++++++++
 include/linux/kvm_para.h    |  112 ++++----------------------------------
 3 files changed, 251 insertions(+), 99 deletions(-)

Index: kvm/include/asm-x86/kvm_para.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ kvm/include/asm-x86/kvm_para.h	2007-10-11 14:05:25.000000000 +0200
@@ -0,0 +1,108 @@
+#ifndef __X86_KVM_PARA_H
+#define __X86_KVM_PARA_H
+
+/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
+ * should be used to determine that a VM is running under KVM.
+ */
+#define KVM_CPUID_SIGNATURE	0x40000000
+
+/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
+ * paravirtualization, the appropriate feature bit should be checked.
+ */
+#define KVM_CPUID_FEATURES	0x40000001
+
+/* Return values for hypercalls */
+#define KVM_ENOSYS		1000
+
+#ifdef __KERNEL__
+#include <asm/processor.h>
+
+/* This instruction is vmcall.  On non-VT architectures, it will generate a
+ * trap that we will then rewrite to the appropriate instruction.
+ */
+#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
+
+/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
+ * instruction.  The hypervisor may replace it with something else but only the
+ * instructions are guaranteed to be supported.
+ *
+ * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
+ * The hypercall number should be placed in rax and the return value will be
+ * placed in rax.  No other registers will be clobbered unless explicited
+ * noted by the particular hypercall.
+ */
+
+static inline long kvm_hypercall0(unsigned int nr)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr));
+	return ret;
+}
+
+static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1));
+	return ret;
+}
+
+static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
+				  unsigned long p2)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2));
+	return ret;
+}
+
+static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
+	return ret;
+}
+
+static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3,
+				  unsigned long p4)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
+	return ret;
+}
+
+static inline int kvm_para_available(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+	char signature[13];
+
+	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
+	memcpy(signature + 0, &ebx, 4);
+	memcpy(signature + 4, &ecx, 4);
+	memcpy(signature + 8, &edx, 4);
+	signature[12] = 0;
+
+	if (strcmp(signature, "KVMKVMKVM") == 0)
+		return 1;
+
+	return 0;
+}
+
+static inline unsigned int kvm_arch_para_features(void)
+{
+	return cpuid_eax(KVM_CPUID_FEATURES);
+}
+
+#endif
+
+#endif
Index: kvm/include/linux/kvm_para.h
===================================================================
--- kvm.orig/include/linux/kvm_para.h	2007-10-11 13:28:46.000000000 +0200
+++ kvm/include/linux/kvm_para.h	2007-10-11 14:06:47.000000000 +0200
@@ -1,110 +1,36 @@
 #ifndef __LINUX_KVM_PARA_H
 #define __LINUX_KVM_PARA_H
 
-/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
- * should be used to determine that a VM is running under KVM.
+/*
+ * This header file provides a method for making a hypercall to the host
+ * Architectures should define:
+ * - kvm_hypercall0, kvm_hypercall1...
+ * - kvm_arch_para_features
+ * - kvm_para_available
  */
-#define KVM_CPUID_SIGNATURE	0x40000000
-
-/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
- * paravirtualization, the appropriate feature bit should be checked.
- */
-#define KVM_CPUID_FEATURES	0x40000001
-
-/* Return values for hypercalls */
-#define KVM_ENOSYS		1000
 
 #ifdef __KERNEL__
-#include <asm/processor.h>
-
-/* This instruction is vmcall.  On non-VT architectures, it will generate a
- * trap that we will then rewrite to the appropriate instruction.
+/*
+ * hypercalls use architecture specific
  */
-#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
-
-/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
- * instruction.  The hypervisor may replace it with something else but only the
- * instructions are guaranteed to be supported.
- *
- * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
- * The hypercall number should be placed in rax and the return value will be
- * placed in rax.  No other registers will be clobbered unless explicited
- * noted by the particular hypercall.
- */
-
-static inline long kvm_hypercall0(unsigned int nr)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr));
-	return ret;
-}
-
-static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1));
-	return ret;
-}
-
-static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
-				  unsigned long p2)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1), "c"(p2));
-	return ret;
-}
-
-static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
-				  unsigned long p2, unsigned long p3)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
-	return ret;
-}
-
-static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
-				  unsigned long p2, unsigned long p3,
-				  unsigned long p4)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
-	return ret;
-}
-
-static inline int kvm_para_available(void)
-{
-	unsigned int eax, ebx, ecx, edx;
-	char signature[13];
-
-	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
-	memcpy(signature + 0, &ebx, 4);
-	memcpy(signature + 4, &ecx, 4);
-	memcpy(signature + 8, &edx, 4);
-	signature[12] = 0;
-
-	if (strcmp(signature, "KVMKVMKVM") == 0)
-		return 1;
-
-	return 0;
-}
+#include <asm/kvm_para.h>
 
 static inline int kvm_para_has_feature(unsigned int feature)
 {
-	if (cpuid_eax(KVM_CPUID_FEATURES) & (1UL << feature))
+	if (kvm_arch_para_features() & (1UL << feature))
 		return 1;
 	return 0;
 }
 
-#endif
 
+#define kvm_hypercall(nr_params, args...)		\
+({							\
+	long __ret;					\
+							\
+	__ret = kvm_hypercall##nr_params(args);		\
+							\
+	__ret;						\
+})
+
+#endif
 #endif
Index: kvm/include/asm-s390/kvm_para.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ kvm/include/asm-s390/kvm_para.h	2007-10-11 14:09:12.000000000 +0200
@@ -0,0 +1,146 @@
+#ifndef __S390_KVM_PARA_H
+#define __S390_KVM_PARA_H
+
+/*
+ * This is subject to change:
+ *
+ * Hypercalls for KVM on s390. The calling convention is similar to the
+ * s390 ABI, so we use R2-R6 for parameters 1-5. In addition we use R1
+ * as hypercall number and R7 as parameter 6. The return value is
+ * written to R2. We use the diagnose instruction as hypercall. To avoid
+ * conflicts with existing diagnoses for LPAR and z/VM, we do not use
+ * the instruction encoded number, but specify the number in R1 and
+ * use 0xBB as KVM diagnose number.
+ *
+ * Copyright 2007, IBM Corp.
+ * Author(s) Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+static inline long kvm_hypercall0(unsigned long nr)
+{
+	register unsigned long __nr asm("1") = nr;
+	register long __rc asm("2");
+
+	asm volatile ("diag 2,4,0xBB\n"
+		      : "=d" (__rc) : "d" (__nr): "memory", "cc");
+	return __rc;
+}
+
+static inline long kvm_hypercall1(unsigned long nr, unsigned long p1)
+{
+	register unsigned long __nr asm("1") = nr;
+	register unsigned long __p1 asm("2") = p1;
+	register long __rc asm("2");
+
+	asm volatile ("diag 2,4,0xBB\n"
+		      : "=d" (__rc) : "d" (__nr), "0" (__p1) : "memory", "cc");
+	return __rc;
+}
+
+static inline long kvm_hypercall2(unsigned long nr, unsigned long p1,
+			       unsigned long p2)
+{
+	register unsigned long __nr asm("1") = nr;
+	register unsigned long __p1 asm("2") = p1;
+	register unsigned long __p2 asm("3") = p2;
+	register long __rc asm("2");
+
+	asm volatile ("diag 2,4,0xBB\n"
+		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2)
+		      : "memory", "cc");
+	return __rc;
+}
+
+static inline long kvm_hypercall3(unsigned long nr, unsigned long p1,
+			       unsigned long p2, unsigned long p3)
+{
+	register unsigned long __nr asm("1") = nr;
+	register unsigned long __p1 asm("2") = p1;
+	register unsigned long __p2 asm("3") = p2;
+	register unsigned long __p3 asm("4") = p3;
+	register long __rc asm("2");
+
+	asm volatile ("diag 2,4,0xBB\n"
+		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+			"d" (__p3) : "memory", "cc");
+	return __rc;
+}
+
+
+static inline long kvm_hypercall4(unsigned long nr, unsigned long p1,
+			       unsigned long p2, unsigned long p3,
+			       unsigned long p4)
+{
+	register unsigned long __nr asm("1") = nr;
+	register unsigned long __p1 asm("2") = p1;
+	register unsigned long __p2 asm("3") = p2;
+	register unsigned long __p3 asm("4") = p3;
+	register unsigned long __p4 asm("5") = p4;
+	register long __rc asm("2");
+
+	asm volatile ("diag 2,4,0xBB\n"
+		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+			"d" (__p3), "d" (__p4) : "memory", "cc");
+	return __rc;
+}
+
+static inline long kvm_hypercall5(unsigned long nr, unsigned long p1,
+			       unsigned long p2, unsigned long p3,
+			       unsigned long p4, unsigned long p5)
+{
+	register unsigned long __nr asm("1") = nr;
+	register unsigned long __p1 asm("2") = p1;
+	register unsigned long __p2 asm("3") = p2;
+	register unsigned long __p3 asm("4") = p3;
+	register unsigned long __p4 asm("5") = p4;
+	register unsigned long __p5 asm("6") = p5;
+	register long __rc asm("2");
+
+	asm volatile ("diag 2,4,0xBB\n"
+		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+			"d" (__p3), "d" (__p4), "d" (__p5)  : "memory", "cc");
+	return __rc;
+}
+
+static inline long kvm_hypercall6(unsigned long nr, unsigned long p1,
+			       unsigned long p2, unsigned long p3,
+			       unsigned long p4, unsigned long p5,
+			       unsigned long p6)
+{
+	register unsigned long __nr asm("1") = nr;
+	register unsigned long __p1 asm("2") = p1;
+	register unsigned long __p2 asm("3") = p2;
+	register unsigned long __p3 asm("4") = p3;
+	register unsigned long __p4 asm("5") = p4;
+	register unsigned long __p5 asm("6") = p5;
+	register unsigned long __p6 asm("7") = p6;
+	register long __rc asm("2");
+
+	asm volatile ("diag 2,4,0xBB\n"
+		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
+			"d" (__p3), "d" (__p4), "d" (__p5), "d" (__p6)
+		      : "memory", "cc");
+	return __rc;
+}
+
+/*
+ * FIXME: make a real check as soon as we define how to check
+ */
+static inline int kvm_para_available(void)
+{
+	return 1;
+}
+
+/*
+ * FIXME: return available features
+ */
+static inline unsigned int kvm_arch_para_features(void)
+{
+	return 0;
+}
+
+
+
+#endif /* __S390_KVM_PARA_H */


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Re: [PATCH/RFC] Per-architecture hypercall definitions

[Avi Kivity]

Christian Borntraeger wrote:
> Currently kvm provides hypercalls only for x86* architectures. To
> provide hypercall infrastructure for other kvm architectures I split
> kvm_para.h into a generic header file and architecture specific
> definitions.
> Currently there are definitions for s390 (experimental, ABI not final,
> and I still have to find out how to get an assigned diagnose number)
> and x86. I already made the split using the common x86 architecture
> folder that will hit 2.6.24-rc soon. 
>
>   
Looks good.  I'll commit (minus the s390 part) once the x86 merge is 
behind us.


> One point for discussion:
>
> i386 only supports up to 4 parameters. On s390 I coded definitions for
> up to 6 parameters. Are we going to limit kvm to 4 parameters?
>   

I guess we can add more parameters if the need arises.  We don't clobber 
registers so there's no issue with that.



-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH/RFC] Per-architecture hypercall definitions

[Anthony Liguori]

Christian Borntraeger wrote:
> ---
>  include/asm-s390/kvm_para.h |  128 ++++++++++++++++++++++++++++++++++++++++++++
>  include/asm-x86/kvm_para.h  |  110 +++++++++++++++++++++++++++++++++++++
>  include/linux/kvm_para.h    |  112 ++++----------------------------------
>  3 files changed, 251 insertions(+), 99 deletions(-)
>
> Index: kvm/include/asm-x86/kvm_para.h
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ kvm/include/asm-x86/kvm_para.h	2007-10-11 14:05:25.000000000 +0200
> @@ -0,0 +1,108 @@
> +#ifndef __X86_KVM_PARA_H
> +#define __X86_KVM_PARA_H
> +
> +/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
> + * should be used to determine that a VM is running under KVM.
> + */
> +#define KVM_CPUID_SIGNATURE	0x40000000
> +
> +/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
> + * paravirtualization, the appropriate feature bit should be checked.
> + */
> +#define KVM_CPUID_FEATURES	0x40000001
> +
> +/* Return values for hypercalls */
> +#define KVM_ENOSYS		1000
>   

errno's can probably be in common code, right?

>  
> +#define kvm_hypercall(nr_params, args...)		\
> +({							\
> +	long __ret;					\
> +							\
> +	__ret = kvm_hypercall##nr_params(args);		\
> +							\
> +	__ret;						\
> +})
>   

Why store results to a variable?  It would also probably be better to 
use the C99 variadic macro format which would be:

#define kvm_hypercall(nr_params, ...) kvm_hypercall##nr_params(__VA_ARGS__)

I originally had one of these in my paravirt_ops implementation but 
quickly found that the code it produced was pretty ugly.  I think:

kvm_hypercall0(KVM_HYPERCALL_FOO);

Is a lot more understandable than:

kvm_hypercall(0, KVM_HYPERCALL_FOO);

It's much harder to guess with the later what the significance of the 
first parameter is.

Regards,

Anthony Liguori

> +#endif
>  #endif
> Index: kvm/include/asm-s390/kvm_para.h
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ kvm/include/asm-s390/kvm_para.h	2007-10-11 14:09:12.000000000 +0200
> @@ -0,0 +1,146 @@
> +#ifndef __S390_KVM_PARA_H
> +#define __S390_KVM_PARA_H
> +
> +/*
> + * This is subject to change:
> + *
> + * Hypercalls for KVM on s390. The calling convention is similar to the
> + * s390 ABI, so we use R2-R6 for parameters 1-5. In addition we use R1
> + * as hypercall number and R7 as parameter 6. The return value is
> + * written to R2. We use the diagnose instruction as hypercall. To avoid
> + * conflicts with existing diagnoses for LPAR and z/VM, we do not use
> + * the instruction encoded number, but specify the number in R1 and
> + * use 0xBB as KVM diagnose number.
> + *
> + * Copyright 2007, IBM Corp.
> + * Author(s) Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.
> + */
> +
> +static inline long kvm_hypercall0(unsigned long nr)
> +{
> +	register unsigned long __nr asm("1") = nr;
> +	register long __rc asm("2");
> +
> +	asm volatile ("diag 2,4,0xBB\n"
> +		      : "=d" (__rc) : "d" (__nr): "memory", "cc");
> +	return __rc;
> +}
> +
> +static inline long kvm_hypercall1(unsigned long nr, unsigned long p1)
> +{
> +	register unsigned long __nr asm("1") = nr;
> +	register unsigned long __p1 asm("2") = p1;
> +	register long __rc asm("2");
> +
> +	asm volatile ("diag 2,4,0xBB\n"
> +		      : "=d" (__rc) : "d" (__nr), "0" (__p1) : "memory", "cc");
> +	return __rc;
> +}
> +
> +static inline long kvm_hypercall2(unsigned long nr, unsigned long p1,
> +			       unsigned long p2)
> +{
> +	register unsigned long __nr asm("1") = nr;
> +	register unsigned long __p1 asm("2") = p1;
> +	register unsigned long __p2 asm("3") = p2;
> +	register long __rc asm("2");
> +
> +	asm volatile ("diag 2,4,0xBB\n"
> +		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2)
> +		      : "memory", "cc");
> +	return __rc;
> +}
> +
> +static inline long kvm_hypercall3(unsigned long nr, unsigned long p1,
> +			       unsigned long p2, unsigned long p3)
> +{
> +	register unsigned long __nr asm("1") = nr;
> +	register unsigned long __p1 asm("2") = p1;
> +	register unsigned long __p2 asm("3") = p2;
> +	register unsigned long __p3 asm("4") = p3;
> +	register long __rc asm("2");
> +
> +	asm volatile ("diag 2,4,0xBB\n"
> +		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
> +			"d" (__p3) : "memory", "cc");
> +	return __rc;
> +}
> +
> +
> +static inline long kvm_hypercall4(unsigned long nr, unsigned long p1,
> +			       unsigned long p2, unsigned long p3,
> +			       unsigned long p4)
> +{
> +	register unsigned long __nr asm("1") = nr;
> +	register unsigned long __p1 asm("2") = p1;
> +	register unsigned long __p2 asm("3") = p2;
> +	register unsigned long __p3 asm("4") = p3;
> +	register unsigned long __p4 asm("5") = p4;
> +	register long __rc asm("2");
> +
> +	asm volatile ("diag 2,4,0xBB\n"
> +		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
> +			"d" (__p3), "d" (__p4) : "memory", "cc");
> +	return __rc;
> +}
> +
> +static inline long kvm_hypercall5(unsigned long nr, unsigned long p1,
> +			       unsigned long p2, unsigned long p3,
> +			       unsigned long p4, unsigned long p5)
> +{
> +	register unsigned long __nr asm("1") = nr;
> +	register unsigned long __p1 asm("2") = p1;
> +	register unsigned long __p2 asm("3") = p2;
> +	register unsigned long __p3 asm("4") = p3;
> +	register unsigned long __p4 asm("5") = p4;
> +	register unsigned long __p5 asm("6") = p5;
> +	register long __rc asm("2");
> +
> +	asm volatile ("diag 2,4,0xBB\n"
> +		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
> +			"d" (__p3), "d" (__p4), "d" (__p5)  : "memory", "cc");
> +	return __rc;
> +}
> +
> +static inline long kvm_hypercall6(unsigned long nr, unsigned long p1,
> +			       unsigned long p2, unsigned long p3,
> +			       unsigned long p4, unsigned long p5,
> +			       unsigned long p6)
> +{
> +	register unsigned long __nr asm("1") = nr;
> +	register unsigned long __p1 asm("2") = p1;
> +	register unsigned long __p2 asm("3") = p2;
> +	register unsigned long __p3 asm("4") = p3;
> +	register unsigned long __p4 asm("5") = p4;
> +	register unsigned long __p5 asm("6") = p5;
> +	register unsigned long __p6 asm("7") = p6;
> +	register long __rc asm("2");
> +
> +	asm volatile ("diag 2,4,0xBB\n"
> +		      : "=d" (__rc) : "d" (__nr), "0" (__p1), "d" (__p2),
> +			"d" (__p3), "d" (__p4), "d" (__p5), "d" (__p6)
> +		      : "memory", "cc");
> +	return __rc;
> +}
> +
> +/*
> + * FIXME: make a real check as soon as we define how to check
> + */
> +static inline int kvm_para_available(void)
> +{
> +	return 1;
> +}
> +
> +/*
> + * FIXME: return available features
> + */
> +static inline unsigned int kvm_arch_para_features(void)
> +{
> +	return 0;
> +}
> +
> +
> +
> +#endif /* __S390_KVM_PARA_H */
>
>
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Re: [PATCH/RFC] Per-architecture hypercall definitions

[Christian Borntraeger]

> > +/* Return values for hypercalls */
> > +#define KVM_ENOSYS		1000
> >   
> 
> errno's can probably be in common code, right?

Yes, they can. Will move.

> I originally had one of these in my paravirt_ops implementation but 
> quickly found that the code it produced was pretty ugly.  I think:
> 
> kvm_hypercall0(KVM_HYPERCALL_FOO);
> 
> Is a lot more understandable than:
> 
> kvm_hypercall(0, KVM_HYPERCALL_FOO);
> 
> It's much harder to guess with the later what the significance of the 
> first parameter is.

I agree. It seems I can simply remove the kvm_hypercall macro.

Here is the updated patch (without the s390 parts. Will send them later
when ready) and the changes mentioned above.

Avi, Anthony, comments?


[PATCH/RFC] Per-architecture hypercall definitions

Currently kvm provides hypercalls only for x86* architectures. To
provide hypercall infrastructure for other kvm architectures I split
kvm_para.h into a generic header file and architecture specific
definitions.

Signed-off-by: Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>

Index: kvm/include/asm-x86/kvm_para.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ kvm/include/asm-x86/kvm_para.h	2007-10-11 15:41:24.000000000 +0200
@@ -0,0 +1,105 @@
+#ifndef __X86_KVM_PARA_H
+#define __X86_KVM_PARA_H
+
+/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
+ * should be used to determine that a VM is running under KVM.
+ */
+#define KVM_CPUID_SIGNATURE	0x40000000
+
+/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
+ * paravirtualization, the appropriate feature bit should be checked.
+ */
+#define KVM_CPUID_FEATURES	0x40000001
+
+#ifdef __KERNEL__
+#include <asm/processor.h>
+
+/* This instruction is vmcall.  On non-VT architectures, it will generate a
+ * trap that we will then rewrite to the appropriate instruction.
+ */
+#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
+
+/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
+ * instruction.  The hypervisor may replace it with something else but only the
+ * instructions are guaranteed to be supported.
+ *
+ * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
+ * The hypercall number should be placed in rax and the return value will be
+ * placed in rax.  No other registers will be clobbered unless explicited
+ * noted by the particular hypercall.
+ */
+
+static inline long kvm_hypercall0(unsigned int nr)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr));
+	return ret;
+}
+
+static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1));
+	return ret;
+}
+
+static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
+				  unsigned long p2)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2));
+	return ret;
+}
+
+static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
+	return ret;
+}
+
+static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3,
+				  unsigned long p4)
+{
+	long ret;
+	asm volatile(KVM_HYPERCALL
+		     : "=a"(ret)
+		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
+	return ret;
+}
+
+static inline int kvm_para_available(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+	char signature[13];
+
+	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
+	memcpy(signature + 0, &ebx, 4);
+	memcpy(signature + 4, &ecx, 4);
+	memcpy(signature + 8, &edx, 4);
+	signature[12] = 0;
+
+	if (strcmp(signature, "KVMKVMKVM") == 0)
+		return 1;
+
+	return 0;
+}
+
+static inline unsigned int kvm_arch_para_features(void)
+{
+	return cpuid_eax(KVM_CPUID_FEATURES);
+}
+
+#endif
+
+#endif
Index: kvm/include/linux/kvm_para.h
===================================================================
--- kvm.orig/include/linux/kvm_para.h	2007-10-11 13:28:46.000000000 +0200
+++ kvm/include/linux/kvm_para.h	2007-10-11 15:41:53.000000000 +0200
@@ -1,110 +1,29 @@
 #ifndef __LINUX_KVM_PARA_H
 #define __LINUX_KVM_PARA_H
 
-/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
- * should be used to determine that a VM is running under KVM.
+/*
+ * This header file provides a method for making a hypercall to the host
+ * Architectures should define:
+ * - kvm_hypercall0, kvm_hypercall1...
+ * - kvm_arch_para_features
+ * - kvm_para_available
  */
-#define KVM_CPUID_SIGNATURE	0x40000000
-
-/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
- * paravirtualization, the appropriate feature bit should be checked.
- */
-#define KVM_CPUID_FEATURES	0x40000001
 
 /* Return values for hypercalls */
 #define KVM_ENOSYS		1000
 
 #ifdef __KERNEL__
-#include <asm/processor.h>
-
-/* This instruction is vmcall.  On non-VT architectures, it will generate a
- * trap that we will then rewrite to the appropriate instruction.
- */
-#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
-
-/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
- * instruction.  The hypervisor may replace it with something else but only the
- * instructions are guaranteed to be supported.
- *
- * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
- * The hypercall number should be placed in rax and the return value will be
- * placed in rax.  No other registers will be clobbered unless explicited
- * noted by the particular hypercall.
+/*
+ * hypercalls use architecture specific
  */
-
-static inline long kvm_hypercall0(unsigned int nr)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr));
-	return ret;
-}
-
-static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1));
-	return ret;
-}
-
-static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
-				  unsigned long p2)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1), "c"(p2));
-	return ret;
-}
-
-static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
-				  unsigned long p2, unsigned long p3)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
-	return ret;
-}
-
-static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
-				  unsigned long p2, unsigned long p3,
-				  unsigned long p4)
-{
-	long ret;
-	asm volatile(KVM_HYPERCALL
-		     : "=a"(ret)
-		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
-	return ret;
-}
-
-static inline int kvm_para_available(void)
-{
-	unsigned int eax, ebx, ecx, edx;
-	char signature[13];
-
-	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
-	memcpy(signature + 0, &ebx, 4);
-	memcpy(signature + 4, &ecx, 4);
-	memcpy(signature + 8, &edx, 4);
-	signature[12] = 0;
-
-	if (strcmp(signature, "KVMKVMKVM") == 0)
-		return 1;
-
-	return 0;
-}
+#include <asm/kvm_para.h>
 
 static inline int kvm_para_has_feature(unsigned int feature)
 {
-	if (cpuid_eax(KVM_CPUID_FEATURES) & (1UL << feature))
+	if (kvm_arch_para_features() & (1UL << feature))
 		return 1;
 	return 0;
 }
+#endif /* __KERNEL__ */
+#endif /* __LINUX_KVM_PARA_H */
 
-#endif
-
-#endif



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Re: [PATCH/RFC] Per-architecture hypercall definitions

[Anthony Liguori]

Christian Borntraeger wrote:
>
> I agree. It seems I can simply remove the kvm_hypercall macro.
>
> Here is the updated patch (without the s390 parts. Will send them later
> when ready) and the changes mentioned above.
>
> Avi, Anthony, comments?
>   

It looks good to me.

Regards,

Anthony Liguori

> [PATCH/RFC] Per-architecture hypercall definitions
>
> Currently kvm provides hypercalls only for x86* architectures. To
> provide hypercall infrastructure for other kvm architectures I split
> kvm_para.h into a generic header file and architecture specific
> definitions.
>
> Signed-off-by: Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
>
> Index: kvm/include/asm-x86/kvm_para.h
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ kvm/include/asm-x86/kvm_para.h	2007-10-11 15:41:24.000000000 +0200
> @@ -0,0 +1,105 @@
> +#ifndef __X86_KVM_PARA_H
> +#define __X86_KVM_PARA_H
> +
> +/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
> + * should be used to determine that a VM is running under KVM.
> + */
> +#define KVM_CPUID_SIGNATURE	0x40000000
> +
> +/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
> + * paravirtualization, the appropriate feature bit should be checked.
> + */
> +#define KVM_CPUID_FEATURES	0x40000001
> +
> +#ifdef __KERNEL__
> +#include <asm/processor.h>
> +
> +/* This instruction is vmcall.  On non-VT architectures, it will generate a
> + * trap that we will then rewrite to the appropriate instruction.
> + */
> +#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
> +
> +/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
> + * instruction.  The hypervisor may replace it with something else but only the
> + * instructions are guaranteed to be supported.
> + *
> + * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
> + * The hypercall number should be placed in rax and the return value will be
> + * placed in rax.  No other registers will be clobbered unless explicited
> + * noted by the particular hypercall.
> + */
> +
> +static inline long kvm_hypercall0(unsigned int nr)
> +{
> +	long ret;
> +	asm volatile(KVM_HYPERCALL
> +		     : "=a"(ret)
> +		     : "a"(nr));
> +	return ret;
> +}
> +
> +static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
> +{
> +	long ret;
> +	asm volatile(KVM_HYPERCALL
> +		     : "=a"(ret)
> +		     : "a"(nr), "b"(p1));
> +	return ret;
> +}
> +
> +static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
> +				  unsigned long p2)
> +{
> +	long ret;
> +	asm volatile(KVM_HYPERCALL
> +		     : "=a"(ret)
> +		     : "a"(nr), "b"(p1), "c"(p2));
> +	return ret;
> +}
> +
> +static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
> +				  unsigned long p2, unsigned long p3)
> +{
> +	long ret;
> +	asm volatile(KVM_HYPERCALL
> +		     : "=a"(ret)
> +		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
> +	return ret;
> +}
> +
> +static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
> +				  unsigned long p2, unsigned long p3,
> +				  unsigned long p4)
> +{
> +	long ret;
> +	asm volatile(KVM_HYPERCALL
> +		     : "=a"(ret)
> +		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
> +	return ret;
> +}
> +
> +static inline int kvm_para_available(void)
> +{
> +	unsigned int eax, ebx, ecx, edx;
> +	char signature[13];
> +
> +	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
> +	memcpy(signature + 0, &ebx, 4);
> +	memcpy(signature + 4, &ecx, 4);
> +	memcpy(signature + 8, &edx, 4);
> +	signature[12] = 0;
> +
> +	if (strcmp(signature, "KVMKVMKVM") == 0)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +static inline unsigned int kvm_arch_para_features(void)
> +{
> +	return cpuid_eax(KVM_CPUID_FEATURES);
> +}
> +
> +#endif
> +
> +#endif
> Index: kvm/include/linux/kvm_para.h
> ===================================================================
> --- kvm.orig/include/linux/kvm_para.h	2007-10-11 13:28:46.000000000 +0200
> +++ kvm/include/linux/kvm_para.h	2007-10-11 15:41:53.000000000 +0200
> @@ -1,110 +1,29 @@
>  #ifndef __LINUX_KVM_PARA_H
>  #define __LINUX_KVM_PARA_H
>  
> -/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx.  It
> - * should be used to determine that a VM is running under KVM.
> +/*
> + * This header file provides a method for making a hypercall to the host
> + * Architectures should define:
> + * - kvm_hypercall0, kvm_hypercall1...
> + * - kvm_arch_para_features
> + * - kvm_para_available
>   */
> -#define KVM_CPUID_SIGNATURE	0x40000000
> -
> -/* This CPUID returns a feature bitmap in eax.  Before enabling a particular
> - * paravirtualization, the appropriate feature bit should be checked.
> - */
> -#define KVM_CPUID_FEATURES	0x40000001
>  
>  /* Return values for hypercalls */
>  #define KVM_ENOSYS		1000
>  
>  #ifdef __KERNEL__
> -#include <asm/processor.h>
> -
> -/* This instruction is vmcall.  On non-VT architectures, it will generate a
> - * trap that we will then rewrite to the appropriate instruction.
> - */
> -#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
> -
> -/* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
> - * instruction.  The hypervisor may replace it with something else but only the
> - * instructions are guaranteed to be supported.
> - *
> - * Up to four arguments may be passed in rbx, rcx, rdx, and rsi respectively.
> - * The hypercall number should be placed in rax and the return value will be
> - * placed in rax.  No other registers will be clobbered unless explicited
> - * noted by the particular hypercall.
> +/*
> + * hypercalls use architecture specific
>   */
> -
> -static inline long kvm_hypercall0(unsigned int nr)
> -{
> -	long ret;
> -	asm volatile(KVM_HYPERCALL
> -		     : "=a"(ret)
> -		     : "a"(nr));
> -	return ret;
> -}
> -
> -static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
> -{
> -	long ret;
> -	asm volatile(KVM_HYPERCALL
> -		     : "=a"(ret)
> -		     : "a"(nr), "b"(p1));
> -	return ret;
> -}
> -
> -static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
> -				  unsigned long p2)
> -{
> -	long ret;
> -	asm volatile(KVM_HYPERCALL
> -		     : "=a"(ret)
> -		     : "a"(nr), "b"(p1), "c"(p2));
> -	return ret;
> -}
> -
> -static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
> -				  unsigned long p2, unsigned long p3)
> -{
> -	long ret;
> -	asm volatile(KVM_HYPERCALL
> -		     : "=a"(ret)
> -		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3));
> -	return ret;
> -}
> -
> -static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
> -				  unsigned long p2, unsigned long p3,
> -				  unsigned long p4)
> -{
> -	long ret;
> -	asm volatile(KVM_HYPERCALL
> -		     : "=a"(ret)
> -		     : "a"(nr), "b"(p1), "c"(p2), "d"(p3), "S"(p4));
> -	return ret;
> -}
> -
> -static inline int kvm_para_available(void)
> -{
> -	unsigned int eax, ebx, ecx, edx;
> -	char signature[13];
> -
> -	cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
> -	memcpy(signature + 0, &ebx, 4);
> -	memcpy(signature + 4, &ecx, 4);
> -	memcpy(signature + 8, &edx, 4);
> -	signature[12] = 0;
> -
> -	if (strcmp(signature, "KVMKVMKVM") == 0)
> -		return 1;
> -
> -	return 0;
> -}
> +#include <asm/kvm_para.h>
>  
>  static inline int kvm_para_has_feature(unsigned int feature)
>  {
> -	if (cpuid_eax(KVM_CPUID_FEATURES) & (1UL << feature))
> +	if (kvm_arch_para_features() & (1UL << feature))
>  		return 1;
>  	return 0;
>  }
> +#endif /* __KERNEL__ */
> +#endif /* __LINUX_KVM_PARA_H */
>  
> -#endif
> -
> -#endif
>
>
>
>   


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Re: [PATCH/RFC] Per-architecture hypercall definitions

[Avi Kivity]

Christian Borntraeger wrote:
> [PATCH/RFC] Per-architecture hypercall definitions
>
> Currently kvm provides hypercalls only for x86* architectures. To
> provide hypercall infrastructure for other kvm architectures I split
> kvm_para.h into a generic header file and architecture specific
> definitions.
>
>   

Applied, thanks.

-- 
error compiling committee.c: too many arguments to function


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