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

[Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>]

> > +/* 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



-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems?  Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now >> http://get.splunk.com/