From: Paolo Bonzini <pbonzini@redhat.com>
To: Roman Penyaev <roman.penyaev@profitbricks.com>
Cc: Mikhail Sennikovskii <mikhail.sennikovskii@profitbricks.com>,
Gleb Natapov <gleb@kernel.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Andy Lutomirski <luto@amacapital.net>
Subject: Re: [RFC] KVM: SVM: do not drop VMCB CPL to 0 if SS is not present
Date: Tue, 30 May 2017 18:05:40 +0200 [thread overview]
Message-ID: <aae2fc5e-a3ee-5f8e-60aa-7748435becf9@redhat.com> (raw)
In-Reply-To: <CAJrWOzCvCAcHk_b1fCe_Buz36jV4sUqW6tpWqeDLPee3qj6gVA@mail.gmail.com>
On 30/05/2017 17:58, Roman Penyaev wrote:
> Indeed, what is left is eventually take it from SS.RPL. J.
Ahah! :) But I only suggested that in specific cases.
> But jokes aside, with your last patch you seems fixed a race problem
> when "CS.RPL is not equal to the CPL in the few instructions between
> setting CR0.PE and reloading CS".
Yes, exactly. The symptom was a crash (triple fault) when you kept
interrupting with "info cpus" a guest that repeatedly went to protected
mode and back to real mode.
> We will have CPL in var->dpl, and it seems ok. All we need is not
> to lose it on the way kernel->userspace->kernel.
You're right. So what do you think of the other suggestion (svm.c
doesn't clear attributes for unusable registers, QEMU only clears P for
unusable registers)?
Thanks,
Paolo
next prev parent reply other threads:[~2017-05-30 16:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-19 16:14 [RFC] KVM: SVM: do not drop VMCB CPL to 0 if SS is not present Roman Penyaev
2017-05-21 3:31 ` Andy Lutomirski
2017-05-21 7:53 ` Roman Penyaev
2017-05-21 20:19 ` Andy Lutomirski
2017-05-24 19:19 ` Roman Penyaev
2017-05-30 14:47 ` Paolo Bonzini
2017-05-30 17:35 ` Roman Penyaev
2017-05-30 21:09 ` Paolo Bonzini
2017-05-31 10:17 ` Roman Penyaev
2017-05-31 10:50 ` Paolo Bonzini
2017-05-30 15:13 ` Paolo Bonzini
2017-05-30 15:58 ` Roman Penyaev
2017-05-30 16:05 ` Paolo Bonzini [this message]
2017-05-30 16:31 ` Gi-Oh Kim
2017-06-15 21:44 ` Andy Lutomirski
2017-06-16 8:44 ` Roman Penyaev
2017-06-16 16:40 ` Paolo Bonzini
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