From: Joerg Roedel <joro@8bytes.org>
To: Bandan Das <bsd@redhat.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
kvm@vger.kernel.org, "Dirk Müller" <dmueller@suse.com>
Subject: Re: [PATCH] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS
Date: Wed, 7 Oct 2015 13:03:36 +0200 [thread overview]
Message-ID: <20151007110335.GA28811@8bytes.org> (raw)
In-Reply-To: <jpg37xnj2tc.fsf@linux.bootlegged.copy>
On Tue, Oct 06, 2015 at 01:59:27PM -0400, Bandan Das wrote:
> Joerg Roedel <joro@8bytes.org> writes:
> >
> > So svm->vmcb->control.next_rip is only written by hardware or in
> > svm_check_intercept(). Both cases write only to this field, if the
> > hardware supports X86_FEATURE_NRIPS. The write in nested_svm_vmexit only
>
> Not until commit f104765b4f81fd74d69e0eb161e89096deade2db. So, an older L1
> kernel will trigger it.
But we don't care if L1 writes something into its own next_rip, as we
never read this value from its VMCB. We only copy the next_rip value we
get from our shadow-vmcb to it on an emulated vmexit. So I still don't
understand what triggers the reported problem or why the WARN_ON is
necessary.
Joerg
next prev parent reply other threads:[~2015-10-07 11:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-01 11:43 [PATCH] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS Dirk Müller
2015-10-01 12:25 ` Paolo Bonzini
2015-10-01 12:45 ` Dirk Müller
2015-10-01 12:31 ` Paolo Bonzini
2015-10-01 22:31 ` Bandan Das
2015-10-02 6:43 ` Dirk Müller
2015-10-05 1:15 ` Bandan Das
2015-10-05 9:50 ` Joerg Roedel
2015-10-05 16:54 ` Bandan Das
2015-10-05 17:15 ` Joerg Roedel
2015-10-05 17:42 ` Bandan Das
2015-10-06 10:23 ` Joerg Roedel
2015-10-06 18:02 ` Bandan Das
2015-10-05 20:12 ` Dirk Müller
2015-10-05 22:00 ` Bandan Das
2015-10-06 10:28 ` Joerg Roedel
2015-10-06 17:59 ` Bandan Das
2015-10-07 11:03 ` Joerg Roedel [this message]
2015-10-07 12:47 ` [PATCH] kvm: svm: Only propagate next_rip when guest supports it Joerg Roedel
2015-10-07 12:57 ` kbuild test robot
2015-10-07 15:48 ` Bandan Das
2015-10-07 16:14 ` Joerg Roedel
2015-10-07 17:03 ` Dirk Müller
2015-10-07 14:58 ` [PATCH] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS Bandan Das
2015-10-07 15:24 ` Joerg Roedel
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