From: Paolo Bonzini <pbonzini@redhat.com>
To: "Andreas Färber" <afaerber@suse.de>,
"Eduardo Habkost" <ehabkost@redhat.com>,
qemu-devel@nongnu.org
Cc: kvm@vger.kernel.org, Aurelien Jarno <aurelien@aurel32.net>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH v3 5/6] target-i386: Don't enable nested VMX by default
Date: Thu, 30 Oct 2014 08:17:58 +0100 [thread overview]
Message-ID: <5451E626.1000304@redhat.com> (raw)
In-Reply-To: <545126A0.7070802@suse.de>
> Here I'm less certain what the best approach is. As you point out,
> there's an inconsistency that I agree should be fixed. I wonder however
> whether an approach similar to 3/6 for KVM only would be better? I.e.,
> have VMX as a sometimes-KVM-supported feature be listed in the model and
> filter it out for accel=kvm so that -cpu enforce works, but let
> accel=tcg fail with features not implemented.
This would mean that -cpu coreduo,enforce doesn't work on TCG, but -cpu
Nehalem,enforce works. This does not make much sense to me.
In fact, I would even omit the x86_cpu_compat_set_features altogether.
The inclusion of vmx in these models was a mistake, and nested VMX is
not really useful with anything but "-cpu host" because there are too
many capabilities communicated via MSRs rather than CPUID.
Paolo
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: "Andreas Färber" <afaerber@suse.de>,
"Eduardo Habkost" <ehabkost@redhat.com>,
qemu-devel@nongnu.org
Cc: Aurelien Jarno <aurelien@aurel32.net>,
kvm@vger.kernel.org, Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH v3 5/6] target-i386: Don't enable nested VMX by default
Date: Thu, 30 Oct 2014 08:17:58 +0100 [thread overview]
Message-ID: <5451E626.1000304@redhat.com> (raw)
In-Reply-To: <545126A0.7070802@suse.de>
> Here I'm less certain what the best approach is. As you point out,
> there's an inconsistency that I agree should be fixed. I wonder however
> whether an approach similar to 3/6 for KVM only would be better? I.e.,
> have VMX as a sometimes-KVM-supported feature be listed in the model and
> filter it out for accel=kvm so that -cpu enforce works, but let
> accel=tcg fail with features not implemented.
This would mean that -cpu coreduo,enforce doesn't work on TCG, but -cpu
Nehalem,enforce works. This does not make much sense to me.
In fact, I would even omit the x86_cpu_compat_set_features altogether.
The inclusion of vmx in these models was a mistake, and nested VMX is
not really useful with anything but "-cpu host" because there are too
many capabilities communicated via MSRs rather than CPUID.
Paolo
next prev parent reply other threads:[~2014-10-30 7:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 19:39 [PATCH v3 0/6] target-i386: Make most CPU models work with "enforce" out of the box Eduardo Habkost
2014-10-03 19:39 ` [Qemu-devel] " Eduardo Habkost
2014-10-03 19:39 ` [PATCH v3 1/6] pc: Create pc_compat_2_1() functions Eduardo Habkost
2014-10-03 19:39 ` [Qemu-devel] " Eduardo Habkost
2014-10-03 19:39 ` [PATCH v3 2/6] target-i386: Rename KVM auto-feature-enable compat function Eduardo Habkost
2014-10-03 19:39 ` [Qemu-devel] " Eduardo Habkost
2014-10-03 19:39 ` [PATCH v3 3/6] target-i386: Disable CPUID_ACPI by default on KVM mode Eduardo Habkost
2014-10-03 19:39 ` [Qemu-devel] " Eduardo Habkost
2014-10-03 19:39 ` [PATCH v3 4/6] target-i386: Remove unsupported bits from all CPU models Eduardo Habkost
2014-10-03 19:39 ` [Qemu-devel] " Eduardo Habkost
2014-10-29 17:26 ` Andreas Färber
2014-10-29 17:26 ` Andreas Färber
2014-10-03 19:39 ` [PATCH v3 5/6] target-i386: Don't enable nested VMX by default Eduardo Habkost
2014-10-03 19:39 ` [Qemu-devel] " Eduardo Habkost
2014-10-29 17:40 ` Andreas Färber
2014-10-29 17:40 ` Andreas Färber
2014-10-29 19:38 ` Eduardo Habkost
2014-10-29 19:38 ` Eduardo Habkost
2014-10-30 7:17 ` Paolo Bonzini [this message]
2014-10-30 7:17 ` Paolo Bonzini
2014-10-03 19:39 ` [PATCH v3 6/6] target-i386: Disable SVM by default in KVM mode Eduardo Habkost
2014-10-03 19:39 ` [Qemu-devel] " Eduardo Habkost
2014-10-03 22:16 ` [PATCH v3 0/6] target-i386: Make most CPU models work with "enforce" out of the box Paolo Bonzini
2014-10-03 22:16 ` [Qemu-devel] " Paolo Bonzini
2014-11-04 14:52 ` Andreas Färber
2014-11-04 14:52 ` Andreas Färber
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