From: Jan Kiszka <jan.kiszka@siemens.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>, kvm <kvm@vger.kernel.org>
Subject: Re: [RFC][PATCH] KVM: nVMX: Leave VMX mode on apparent CPU reset
Date: Tue, 17 Dec 2013 15:40:47 +0100 [thread overview]
Message-ID: <52B0626F.2090905@siemens.com> (raw)
In-Reply-To: <52B050C6.5090407@redhat.com>
On 2013-12-17 14:25, Paolo Bonzini wrote:
> Il 16/12/2013 10:32, Jan Kiszka ha scritto:
>> As long as we do not expose all the VMX related states to user space,
>> there is no way to properly reset a VCPU when VMX is enabled. Emulate
>> this for now by catching host-side clearings of the feature control MSR.
>> This allows to reboot a VM while it is running some hypervisor code.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>
>> Better ideas? Or continue to leave it as it is?
>
> The final vmx_vcpu_reset is the only really ugly part, but it is
> _really_ ugly... Can you modify QEMU to restore MSRs first, and reduce
> vmx_reset_nested to just
>
> if (is_guest_mode(vcpu))
> nested_vmx_vmexit(vcpu);
>
> free_nested(vmx);
>
> ?
Well, I could make setting of MSR_IA32_FEATURE_CONTROL to 0 an official
"clear VMX" interface. Then QEMU would have to issue this MSR set
request before doing any other CPU state manipulation. Is that what you
have in mind?
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2013-12-17 14:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-16 9:32 [RFC][PATCH] KVM: nVMX: Leave VMX mode on apparent CPU reset Jan Kiszka
2013-12-17 13:25 ` Paolo Bonzini
2013-12-17 14:40 ` Jan Kiszka [this message]
2013-12-17 14:43 ` Paolo Bonzini
2013-12-30 20:02 ` Marcelo Tosatti
2013-12-30 20:05 ` Marcelo Tosatti
2013-12-30 20:02 ` Marcelo Tosatti
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