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From: Paolo Bonzini <pbonzini@redhat.com>
To: Richard Henderson <rth@twiddle.net>, qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, afaerber@suse.de, aliguori@amazon.com
Subject: Re: [Qemu-devel] [PATCH 00/23] qom hooks to clean up cpu_exec
Date: Sat, 13 Sep 2014 22:03:28 +0200	[thread overview]
Message-ID: <5414A310.6000604@redhat.com> (raw)
In-Reply-To: <1410626712-3683-1-git-send-email-rth@twiddle.net>

Il 13/09/2014 18:44, Richard Henderson ha scritto:
> 
> After the 23 patches, there's one (interesting) ifdef left.
> That is, i386 redefining CPU_INTERRUPT_RESET as CPU_INTERRUPT_INIT
> for its own purposes.  I'm not sure why all that couldn't be done
> under whatever hooks cpu_reset allows.

There are two reasons.

One is because INIT is intentionally weaker than RESET.  For example, it
doesn't clear many MSRs and the FPU state.

The second is because INIT can be intercepted by the virtual machine
monitor if SVM is enabled (KVM doesn't use it, but it is useful for
example when the virtual machine monitor is letting the virtual machine
use the hardware APIC).

The latter could well happen on more targets than just x86, so perhaps
we can have a reset_interrupt method that defaults to reset and is
overridden by x86?

> Failing that, we might be
> able to redefine C_I_I as a new CPU_INTERRUPT_TGT_INT_3 bit.

That would break migration, though admittedly only in a somewhat remote
case.

Paolo

  reply	other threads:[~2014-09-13 20:03 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-13 16:44 [Qemu-devel] [PATCH 00/23] qom hooks to clean up cpu_exec Richard Henderson
2014-09-13 20:03 ` Paolo Bonzini [this message]
2014-09-13 16:45 Richard Henderson
2014-09-26 10:45 ` Peter Maydell

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