From: Christian Borntraeger <borntraeger@de.ibm.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Andrey Shinkevich" <andrey.shinkevich@virtuozzo.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org
Cc: vsementsov@virtuozzo.com, berto@igalia.com, ehabkost@redhat.com,
kvm@vger.kernel.org, mtosatti@redhat.com,
mdroth@linux.vnet.ibm.com, armbru@redhat.com,
pbonzini@redhat.com, den@openvz.org, rth@twiddle.net
Subject: Re: [Qemu-devel] [PATCH 3/3] i386/kvm: initialize struct at full before ioctl call
Date: Tue, 30 Jul 2019 19:47:23 +0200 [thread overview]
Message-ID: <cfdfca59-283d-a73d-5a49-b010e1b50633@de.ibm.com> (raw)
In-Reply-To: <e78f8ce4-3dcf-61b1-1eec-bd28f6ba9b4c@redhat.com>
On 30.07.19 19:14, Philippe Mathieu-Daudé wrote:
> On 7/30/19 7:05 PM, Christian Borntraeger wrote:
>> On 30.07.19 18:44, Philippe Mathieu-Daudé wrote:
>>> On 7/30/19 6:01 PM, Andrey Shinkevich wrote:
>>>> Not the whole structure is initialized before passing it to the KVM.
>>>> Reduce the number of Valgrind reports.
>>>>
>>>> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
>>>> ---
>>>> target/i386/kvm.c | 3 +++
>>>> 1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
>>>> index dbbb137..ed57e31 100644
>>>> --- a/target/i386/kvm.c
>>>> +++ b/target/i386/kvm.c
>>>> @@ -190,6 +190,7 @@ static int kvm_get_tsc(CPUState *cs)
>>>> return 0;
>>>> }
>>>>
>>>> + memset(&msr_data, 0, sizeof(msr_data));
>>>
>>> I wonder the overhead of this one...
>>
>> Cant we use designated initializers like in
>>
>> commit bdfc8480c50a53d91aa9a513d23a84de0d5fbc86
>> Author: Christian Borntraeger <borntraeger@de.ibm.com>
>> AuthorDate: Thu Oct 30 09:23:41 2014 +0100
>> Commit: Paolo Bonzini <pbonzini@redhat.com>
>> CommitDate: Mon Dec 15 12:21:01 2014 +0100
>>
>> valgrind/i386: avoid false positives on KVM_SET_XCRS ioctl
>>
>> and others?
>
> Is the compiler smart enough to figure out it doesn't need to zeroes in
> case env->tsc_valid is true and the function returns?
Good question, we would need to double check with objdump.
next prev parent reply other threads:[~2019-07-30 17:49 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 16:01 [Qemu-devel] [PATCH 0/3] Reduce the number of Valgrind reports in unit tests Andrey Shinkevich
2019-07-30 16:01 ` [Qemu-devel] [PATCH 1/3] test-throttle: Fix uninitialized use of burst_length Andrey Shinkevich
2019-08-13 12:19 ` Alberto Garcia
2019-07-30 16:01 ` [Qemu-devel] [PATCH 2/3] tests: Fix uninitialized byte in test_visitor_in_fuzz Andrey Shinkevich
2019-07-30 16:01 ` [Qemu-devel] [PATCH 3/3] i386/kvm: initialize struct at full before ioctl call Andrey Shinkevich
2019-07-30 16:44 ` Philippe Mathieu-Daudé
2019-07-30 17:05 ` Christian Borntraeger
2019-07-30 17:14 ` Philippe Mathieu-Daudé
2019-07-30 17:47 ` Christian Borntraeger [this message]
2019-07-31 9:05 ` Christophe de Dinechin
2019-07-31 12:32 ` Paolo Bonzini
2019-07-31 14:10 ` Andrey Shinkevich
2019-07-30 19:22 ` Paolo Bonzini
2019-07-30 16:46 ` Peter Maydell
2019-07-30 17:09 ` Christian Borntraeger
2019-07-30 19:20 ` Paolo Bonzini
2019-07-31 7:24 ` Christian Borntraeger
2019-07-31 12:04 ` Andrey Shinkevich
2019-07-31 12:28 ` Christian Borntraeger
2019-07-31 12:43 ` Christian Borntraeger
2019-07-31 13:03 ` Paolo Bonzini
2019-07-31 14:11 ` Andrey Shinkevich
2019-08-13 12:02 ` [Qemu-devel] [PATCH 0/3] Reduce the number of Valgrind reports in unit tests Andrey Shinkevich
2019-08-13 12:05 ` Paolo Bonzini
2019-08-13 12:08 ` Andrey Shinkevich
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