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From 42405600b468b79523f7e8171c1aac4a3d012792 Mon Sep 17 00:00:00 2001
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From: Eduardo Habkost <ehabkost@redhat.com>
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Date: Tue, 21 Aug 2018 19:15:41 +0100
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Subject: [PATCH 1/2] i386: Disable TOPOEXT by default on "-cpu host"
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RH-Author: Eduardo Habkost <ehabkost@redhat.com>
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Message-id: <20180821191541.31916-2-ehabkost@redhat.com>
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Patchwork-id: 81904
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O-Subject: [qemu-kvm RHEL8/virt212 PATCH v2 1/1] i386: Disable TOPOEXT by default on "-cpu host"
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Bugzilla: 1619804
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
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Enabling TOPOEXT is always allowed, but it can't be enabled
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blindly by "-cpu host" because it may make guests crash if the
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rest of the cache topology information isn't provided or isn't
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consistent.
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This addresses the bug reported at:
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https://bugzilla.redhat.com/show_bug.cgi?id=1613277
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Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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Message-Id: <20180809221852.15285-1-ehabkost@redhat.com>
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Tested-by: Richard W.M. Jones <rjones@redhat.com>
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Reviewed-by: Babu Moger <babu.moger@amd.com>
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Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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(cherry picked from commit 7210a02c58572b2686a3a8d610c6628f87864aed)
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Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 target/i386/cpu.c | 6 ++++++
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 1 file changed, 6 insertions(+)
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diff --git a/target/i386/cpu.c b/target/i386/cpu.c
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index 605d0fa..e16dba7 100644
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--- a/target/i386/cpu.c
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+++ b/target/i386/cpu.c
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@@ -852,6 +852,12 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
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         },
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         .cpuid_eax = 0x80000001, .cpuid_reg = R_ECX,
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         .tcg_features = TCG_EXT3_FEATURES,
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+        /*
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+         * TOPOEXT is always allowed but can't be enabled blindly by
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+         * "-cpu host", as it requires consistent cache topology info
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+         * to be provided so it doesn't confuse guests.
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+         */
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+        .no_autoenable_flags = CPUID_EXT3_TOPOEXT,
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     },
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     [FEAT_C000_0001_EDX] = {
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         .feat_names = {
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-- 
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1.8.3.1
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