From: Paolo Bonzini <pbonzini@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>, Bandan Das <bsd@redhat.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH kvm-unit-tests 1/2] VMX: checks for validity of vmxon region
Date: Thu, 05 Jun 2014 12:35:41 +0200 [thread overview]
Message-ID: <539047FD.9070002@redhat.com> (raw)
In-Reply-To: <53901573.4020004@siemens.com>
Il 05/06/2014 09:00, Jan Kiszka ha scritto:
>> > + rflags = read_rflags() | X86_EFLAGS_CF | X86_EFLAGS_ZF;
>> > + write_rflags(rflags);
>> > + ret1 = vmx_on();
> Can we ensure that the compiler doesn't inject any ops between
> write_rflags and the vmxon that overwrite CF or ZF?
No, in fact if vmx_on were not inlined, building the stack frame with
"sub" would overwrite the flags.
Paolo
> If you want those
> flags in a specific state, maybe it's better to pass that to vmx_on and
> do this in the assembly block with vmxon.
>
next prev parent reply other threads:[~2014-06-05 10:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-04 21:17 [PATCH kvm-unit-tests 0/2] More nvmx unit tests changes Bandan Das
2014-06-04 21:17 ` [PATCH kvm-unit-tests 1/2] VMX: checks for validity of vmxon region Bandan Das
2014-06-05 7:00 ` Jan Kiszka
2014-06-05 10:35 ` Paolo Bonzini [this message]
2014-06-04 21:17 ` [PATCH kvm-unit-tests 2/2] VMX: Check for validity of vmcs region when calling vmclear/vmptrld Bandan Das
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