On 2018/6/12 23:29, James Morse wrote:

Hi gengdongjiu,

On 12/06/18 15:50, gengdongjiu wrote:

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On 2018/6/11 21:36, James Morse wrote:

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On 08/06/18 20:48, Dongjiu Geng wrote:

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For the migrating VMs, user space may need to know the exception
state. For example, in the machine A, KVM make an SError pending,
when migrate to B, KVM also needs to pend an SError.

This new IOCTL exports user-invisible states related to SError.
Together with appropriate user space changes, user space can get/set
the SError exception state to do migrate/snapshot/suspend.

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diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
index caae484..c3e6975 100644
--- a/arch/arm/include/uapi/asm/kvm.h
+++ b/arch/arm/include/uapi/asm/kvm.h

@@ -124,6 +124,18 @@ struct kvm_sync_regs {
 struct kvm_arch_memory_slot {
 };
 
+/* for KVM_GET/SET_VCPU_EVENTS */
+struct kvm_vcpu_events {
+	struct {
+		__u8 serror_pending;
+		__u8 serror_has_esr;
+		/* Align it to 8 bytes */
+		__u8 pad[6];
+		__u64 serror_esr;
+	} exception;
+	__u32 reserved[12];
+};
+

You haven't defined __KVM_HAVE_VCPU_EVENTS for 32bit, so presumably this struct
will never be used. Why is it here?

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  if not add it for 32 bits. the 32 arm platform will build Fail, whether you have good
   idea to avoid this Failure if not add this struct for the 32 bit?

How does this 32bit code build without this patch?
If do you provide the struct, how will that code build with older headers?

As far as I can see, this is what the __KVM_HAVE_VCPU_EVENTS define is for.

This should be both, or neither. Having just the struct is useless.

It because the caller of kvm_arm_vcpu_get/set_events() is in "virt/kvm/arm/arm.c".
the virt/kvm/arm/arm.c will used by both arm64 and arm.
so It needs to add kvm_arm_vcpu_get/set_events() for the 32 bits, however, kvm_arm_vcpu_get/set_events() will directly return,

I attached the build erros below:
https://lkml.org/lkml/2018/6/4/918
https://lkml.org/lkml/2018/6/4/873


[..]
I will continue check below comments, thanks