KVM: Add async pf flag to KVM_GET/SET_VCPU_EVENTS interface

From: Wanpeng Li <wanpeng.li@hotmail.com>

This patch adds async pf flag to KVM_GET/SET_VCPU_EVENTS interface.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
 linux-headers/asm-x86/kvm.h | 2 ++
 target/i386/cpu.h           | 1 +
 target/i386/kvm.c           | 6 +++++-
 3 files changed, 8 insertions(+), 1 deletion(-)

Hi,

This series seems to have some coding style problems. See output below for
more information:

Subject: [Qemu-devel] [PATCH] KVM: Add async pf flag to KVM_GET/SET_VCPU_EVENTS interface
Type: series
Message-id: 1498014889-52658-1-git-send-email-wanpeng.li@hotmail.com

=== TEST SCRIPT BEGIN ===
#!/bin/bash

BASE=base
n=1
total=$(git log --oneline $BASE.. | wc -l)
failed=0

git config --local diff.renamelimit 0
git config --local diff.renames True

commits="$(git log --format=%H --reverse $BASE..)"
for c in $commits; do
    echo "Checking PATCH $n/$total: $(git log -n 1 --format=%s $c)..."
    if ! git show $c --format=email | ./scripts/checkpatch.pl --mailback -; then
        failed=1
        echo
    fi
    n=$((n+1))
done

exit $failed
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
Switched to a new branch 'test'
4910d5f KVM: Add async pf flag to KVM_GET/SET_VCPU_EVENTS interface

=== OUTPUT BEGIN ===
Checking PATCH 1/1: KVM: Add async pf flag to KVM_GET/SET_VCPU_EVENTS interface...
ERROR: code indent should never use tabs
#61: FILE: target/i386/kvm.c:2535:
+^I^I             KVM_VCPUEVENT_VALID_ASYNC_PF;$

ERROR: braces {} are necessary for all arms of this statement
#69: FILE: target/i386/kvm.c:2560:
+    if (events.flags & KVM_VCPUEVENT_VALID_ASYNC_PF)
[...]

total: 2 errors, 0 warnings, 45 lines checked

Your patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

=== OUTPUT END ===

Test command exited with code: 1


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2017-06-20 20:14-0700, Wanpeng Li:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> This patch adds async pf flag to KVM_GET/SET_VCPU_EVENTS interface.
> 
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---
> diff --git a/linux-headers/asm-x86/kvm.h b/linux-headers/asm-x86/kvm.h
> @@ -300,6 +301,7 @@ struct kvm_vcpu_events {
>  		__u8 has_error_code;
>  		__u8 pad;
>  		__u32 error_code;
> +		bool async_page_fault;

Touching userspace interfaces is always a major fun ...

You must not change the layout of an existing structure.  You can try to
reuse the pad and hope that some userspace didn't check it for 0.
(I think it's a decent compromise between safety and sanity.)

>  	} exception;
>  	struct {
>  		__u8 injected;
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> @@ -2493,6 +2493,7 @@ static int kvm_put_vcpu_events(X86CPU *cpu, int level)
>      events.exception.has_error_code = env->has_error_code;
>      events.exception.error_code = env->error_code;
>      events.exception.pad = 0;
> +    events.exception.async_page_fault = env->async_page_fault;
>  
>      events.interrupt.injected = (env->interrupt_injected >= 0);

Old QEMUs would break below this point, because interrupt.injected used
to be where exception.async_page_fault is.

>      events.interrupt.nr = env->interrupt_injected;

2017-06-22 0:28 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>:
> 2017-06-20 20:14-0700, Wanpeng Li:
>> From: Wanpeng Li <wanpeng.li@hotmail.com>
>>
>> This patch adds async pf flag to KVM_GET/SET_VCPU_EVENTS interface.
>>
>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
>> ---
>> diff --git a/linux-headers/asm-x86/kvm.h b/linux-headers/asm-x86/kvm.h
>> @@ -300,6 +301,7 @@ struct kvm_vcpu_events {
>>               __u8 has_error_code;
>>               __u8 pad;
>>               __u32 error_code;
>> +             bool async_page_fault;
>
> Touching userspace interfaces is always a major fun ...
>
> You must not change the layout of an existing structure.  You can try to
> reuse the pad and hope that some userspace didn't check it for 0.
> (I think it's a decent compromise between safety and sanity.)

Thanks for pointing out. Just fixes it in v2.

Regards,
Wanpeng Li

>
>>       } exception;
>>       struct {
>>               __u8 injected;
>> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
>> @@ -2493,6 +2493,7 @@ static int kvm_put_vcpu_events(X86CPU *cpu, int level)
>>      events.exception.has_error_code = env->has_error_code;
>>      events.exception.error_code = env->error_code;
>>      events.exception.pad = 0;
>> +    events.exception.async_page_fault = env->async_page_fault;
>>
>>      events.interrupt.injected = (env->interrupt_injected >= 0);
>
> Old QEMUs would break below this point, because interrupt.injected used
> to be where exception.async_page_fault is.
>
>>      events.interrupt.nr = env->interrupt_injected;