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From 42405600b468b79523f7e8171c1aac4a3d012792 Mon Sep 17 00:00:00 2001
From: Eduardo Habkost <ehabkost@redhat.com>
Date: Tue, 21 Aug 2018 19:15:41 +0100
Subject: [PATCH 1/2] i386: Disable TOPOEXT by default on "-cpu host"

RH-Author: Eduardo Habkost <ehabkost@redhat.com>
Message-id: <20180821191541.31916-2-ehabkost@redhat.com>
Patchwork-id: 81904
O-Subject: [qemu-kvm RHEL8/virt212 PATCH v2 1/1] i386: Disable TOPOEXT by default on "-cpu host"
Bugzilla: 1619804
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Igor Mammedov <imammedo@redhat.com>

Enabling TOPOEXT is always allowed, but it can't be enabled
blindly by "-cpu host" because it may make guests crash if the
rest of the cache topology information isn't provided or isn't
consistent.

This addresses the bug reported at:
https://bugzilla.redhat.com/show_bug.cgi?id=1613277

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180809221852.15285-1-ehabkost@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
(cherry picked from commit 7210a02c58572b2686a3a8d610c6628f87864aed)
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 target/i386/cpu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 605d0fa..e16dba7 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -852,6 +852,12 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         },
         .cpuid_eax = 0x80000001, .cpuid_reg = R_ECX,
         .tcg_features = TCG_EXT3_FEATURES,
+        /*
+         * TOPOEXT is always allowed but can't be enabled blindly by
+         * "-cpu host", as it requires consistent cache topology info
+         * to be provided so it doesn't confuse guests.
+         */
+        .no_autoenable_flags = CPUID_EXT3_TOPOEXT,
     },
     [FEAT_C000_0001_EDX] = {
         .feat_names = {
-- 
1.8.3.1