From: Paolo Bonzini <pbonzini@redhat.com>
To: Arthur Chunqi Li <yzt356@gmail.com>
Cc: Jan Kiszka <jan.kiszka@web.de>, kvm <kvm@vger.kernel.org>,
Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH 2/4] kvm-unit-tests: VMX: Add test cases for CR0/4 shadowing
Date: Sun, 18 Aug 2013 16:07:47 +0200 [thread overview]
Message-ID: <5210D533.1010703@redhat.com> (raw)
In-Reply-To: <CABpY8ML6LnFNTrg8HUXwzqNZsqf4-6cCMgJoboF11mKAR2tpng@mail.gmail.com>
Il 15/08/2013 09:59, Arthur Chunqi Li ha scritto:
>> > volatile u32 stage? And we have barrier() to avoid reordering.
> Reordering here is not a big deal here, though it is actually needed
> here. I occurred the following problem:
>
> stage = 1;
> do something that causes vmexit;
> stage = 2;
>
> Then the compiler will optimize "stage = 1" and "stage = 2" to one
> instruction "stage =2", since instructions between them don't use
> "stage". Can volatile solve this problem?
I'm not sure if volatile stores are reordered against non-volatile stores.
Better keep set_stage() but write it as
barrier();
stage = s;
barrier();
Paolo
next prev parent reply other threads:[~2013-08-18 14:08 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-13 15:56 [PATCH 0/4] kvm-unit-tests: Add a series of test cases Arthur Chunqi Li
2013-08-13 15:56 ` [PATCH 1/4] kvm-unit-tests: VMX: Add test cases for PAT and EFER Arthur Chunqi Li
2013-08-15 7:17 ` Jan Kiszka
2013-08-15 7:41 ` Arthur Chunqi Li
2013-08-15 7:48 ` Jan Kiszka
2013-08-15 8:05 ` Arthur Chunqi Li
2013-08-15 8:09 ` Jan Kiszka
2013-08-13 15:56 ` [PATCH 2/4] kvm-unit-tests: VMX: Add test cases for CR0/4 shadowing Arthur Chunqi Li
2013-08-15 7:30 ` Jan Kiszka
2013-08-15 7:40 ` Arthur Chunqi Li
2013-08-15 7:47 ` Jan Kiszka
2013-08-15 7:59 ` Arthur Chunqi Li
2013-08-15 8:07 ` Jan Kiszka
2013-08-18 14:07 ` Paolo Bonzini [this message]
2013-08-18 14:32 ` Gmail
2013-08-13 15:56 ` [PATCH 3/4] kvm-unit-tests: VMX: Add test cases for I/O bitmaps Arthur Chunqi Li
2013-08-15 7:40 ` Jan Kiszka
2013-08-15 7:51 ` Arthur Chunqi Li
2013-08-15 7:58 ` Jan Kiszka
2013-08-15 8:09 ` Arthur Chunqi Li
2013-08-15 8:13 ` Jan Kiszka
2013-08-15 8:20 ` Arthur Chunqi Li
2013-08-15 8:23 ` Jan Kiszka
2013-08-15 10:43 ` Arthur Chunqi Li
2013-08-13 15:56 ` [PATCH 4/4] kvm-unit-tests: VMX: Add test cases for instruction interception Arthur Chunqi Li
2013-08-15 8:06 ` Jan Kiszka
2013-08-15 8:16 ` Arthur Chunqi Li
2013-08-15 8:20 ` Jan Kiszka
2013-08-15 8:35 ` Arthur Chunqi Li
2013-08-15 8:40 ` Jan Kiszka
2013-08-15 8:48 ` Arthur Chunqi Li
2013-08-15 9:15 ` Jan Kiszka
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