On Mon, Apr 13, 2015 at 03:51:33PM +0100, Alex Bennée wrote:

Christoffer Dall [off-list ref] writes:

quoted

On Tue, Mar 31, 2015 at 04:08:00PM +0100, Alex Bennée wrote:

quoted

Currently x86, powerpc and soon arm64 use the same two architecture
specific bits for guest debug support for software and hardware
breakpoints. This makes the shared values explicit while leaving the
gate open for another architecture to use some other value if they
really really want to.

Signed-off-by: Alex Bennée <redacted>

diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index ab4d473..1731569 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h

@@ -310,8 +310,8 @@ struct kvm_guest_debug_arch {
  * and upper 16 bits are architecture specific. Architecture specific defines
  * that ioctl is for setting hardware breakpoint or software breakpoint.
  */
-#define KVM_GUESTDBG_USE_SW_BP		0x00010000
-#define KVM_GUESTDBG_USE_HW_BP		0x00020000
+#define KVM_GUESTDBG_USE_SW_BP		__KVM_GUESTDBG_USE_SW_BP
+#define KVM_GUESTDBG_USE_HW_BP		__KVM_GUESTDBG_USE_HW_BP
 
 /* definition of registers in kvm_run */
 struct kvm_sync_regs {

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index d7dcef5..1438202 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h

@@ -250,8 +250,8 @@ struct kvm_debug_exit_arch {
 	__u64 dr7;
 };
 
-#define KVM_GUESTDBG_USE_SW_BP		0x00010000
-#define KVM_GUESTDBG_USE_HW_BP		0x00020000
+#define KVM_GUESTDBG_USE_SW_BP		__KVM_GUESTDBG_USE_SW_BP
+#define KVM_GUESTDBG_USE_HW_BP		__KVM_GUESTDBG_USE_HW_BP
 #define KVM_GUESTDBG_INJECT_DB		0x00040000
 #define KVM_GUESTDBG_INJECT_BP		0x00080000
 

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 5eedf84..ce2db14 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h

@@ -525,8 +525,16 @@ struct kvm_s390_irq {
 
 /* for KVM_SET_GUEST_DEBUG */
 
-#define KVM_GUESTDBG_ENABLE		0x00000001
-#define KVM_GUESTDBG_SINGLESTEP		0x00000002
+#define KVM_GUESTDBG_ENABLE		(1 << 0)
+#define KVM_GUESTDBG_SINGLESTEP	(1 << 1)
+
+/*
+ * Architecture specific stuff uses the top 16 bits of the field,

can you be more specific than 'stuff' here?  features?

quoted

+ * however there is some shared commonality for the common cases

I don't like this sentence; shared commonality is a pleonasm and the use
of however makes it sounds like there's some caveat here.

OK I can see that - after I looked it up ;-)

quoted

If the top 16 bits are indeed arhictecture specific, then I think they
should just be defined in their architecture specific headers.  Unless
the idea here is that there's a fixed set of of flags that architectures
can choose to support, in which case it should simply be defined in the
common header.

Well an architecture might not support some features and want to use
those bits for something else? I didn't want to force the bottom two
of the architecture specific bits to wasted if the features don't exist.

This change comes from a discussion we had on v1 of this series
http://www.spinics.net/lists/kvm-arm/msg12409.html

quoted

quoted

+ */
+#define __KVM_GUESTDBG_USE_SW_BP	(1 << 16)
+#define __KVM_GUESTDBG_USE_HW_BP	(1 << 17)
+
 
 struct kvm_guest_debug {
 	__u32 control;
-- 
2.3.4

-- 
Alex Bennée