67 lines
2.7 KiB
Diff
67 lines
2.7 KiB
Diff
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From 29c6ee9322da082e3be9faa94cf4a6840b49cd97 Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Fri, 22 Jul 2022 09:36:27 +0200
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Subject: [PATCH] output/create_libvirt_xml: relax VCPU feature checking for
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"qemu64"
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When the source domain doesn't specify a VCPU model ("s_cpu_model" is
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None), and the guest OS is assumed to work with the default VCPU model
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("gcaps_default_cpu" is true), we don't output any <cpu> element. In that
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case, libvirtd augments the domain config with:
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[1] <cpu mode='custom' match='exact' check='none'>
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<model fallback='forbid'>qemu64</model>
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</cpu>
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where the @check='none' attribute ensures that the converted domain will
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be launched, for example, on an Intel host, despite the "qemu64" VCPU
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model containing AMD-only feature flags such as "svm".
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However, if the source domain explicitly specifies the "qemu64" model
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(mostly seen with "-i libvirt -ic qemu://..."), we presently output
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[2] <cpu match='minimum'>
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<model fallback='allow'>qemu64</model>
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</cpu>
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which libvirtd completes as
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[3] <cpu mode='custom' match='minimum' check='partial'>
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<model fallback='allow'>qemu64</model>
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</cpu>
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In [3], cpu/@match='minimum' and cpu/model/@fallback='allow' are both
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laxer than @match='exact' and @fallback='forbid', respectively, in [1].
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However, cpu/@check='partial' in [3] is stricter than @check='none' in
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[1]; it causes libvirtd to catch the "svm" feature flag on an Intel host,
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and prevents the converted domain from starting.
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The "qemu64" VCPU model is supposed to run on every possible host
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<https://gitlab.com/qemu-project/qemu/-/blob/master/docs/system/cpu-models-x86.rst.inc>,
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therefore make an exception for the explicitly specified "qemu64" VCPU
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model, and generate the @check='none' attribute.
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2107503
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Signed-off-by: Laszlo Ersek <lersek@redhat.com>
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Message-Id: <20220722073627.6511-1-lersek@redhat.com>
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Acked-by: Richard W.M. Jones <rjones@redhat.com>
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(cherry picked from commit e5297c3180fd3ebea41a40f4c5a66969a24b9ff3)
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---
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output/create_libvirt_xml.ml | 2 ++
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1 file changed, 2 insertions(+)
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diff --git a/output/create_libvirt_xml.ml b/output/create_libvirt_xml.ml
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index 531a4f75..bd01304d 100644
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--- a/output/create_libvirt_xml.ml
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+++ b/output/create_libvirt_xml.ml
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@@ -192,6 +192,8 @@ let create_libvirt_xml ?pool source inspect
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List.push_back cpu_attrs ("mode", "host-passthrough");
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| Some model ->
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List.push_back cpu_attrs ("match", "minimum");
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+ if model = "qemu64" then
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+ List.push_back cpu_attrs ("check", "none");
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(match source.s_cpu_vendor with
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| None -> ()
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| Some vendor ->
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