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From 6e9de3f3fa020b351960f4f528f175aa802eb536 Mon Sep 17 00:00:00 2001
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From: Eduardo Habkost <ehabkost@redhat.com>
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Date: Wed, 26 Sep 2018 18:50:59 +0200
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Subject: [PATCH] target-i386: cpu: Add downstream-only STIBP CPUID flag
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RH-Author: Eduardo Habkost <ehabkost@redhat.com>
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Message-id: <20180926185059.20691-1-ehabkost@redhat.com>
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Patchwork-id: 82301
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O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH] target-i386: cpu: Add downstream-only STIBP CPUID flag
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Bugzilla: 1638077
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RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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RH-Acked-by: Kashyap Chamarthy <kchamart@redhat.com>
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RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
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From: Paolo Bonzini <pbonzini@redhat.com>
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We accidentally dropped the downstream-only STIBP CPUID flag
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during the 2.12.0 rebase.
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STIBP is a CPUID flag that was considered for the Spectre
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(CVE-2017-5715) mitigations, but in the end it was not necessary:
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spec-ctrl/IBRS was deemed enough. The kernel KVM STIBP CPUID
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code was never merged upstream, but it's present on RHEL-7.
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This means we may have existing VMs created on RHEL-7.5 hosts
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with the STIBP flag enabled, and we need to support
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live-migration of those VMs to RHEL-7.6.
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Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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target/i386/cpu.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/target/i386/cpu.c b/target/i386/cpu.c
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index 6b5acdf..91f5a97 100644
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--- a/target/i386/cpu.c
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+++ b/target/i386/cpu.c
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@@ -1007,7 +1007,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
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NULL, NULL, NULL, NULL,
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NULL, NULL, NULL, NULL,
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NULL, NULL, NULL, NULL,
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- NULL, NULL, "spec-ctrl", NULL,
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+ NULL, NULL, "spec-ctrl", "stibp",
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NULL, NULL, NULL, "ssbd",
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},
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.cpuid_eax = 7,
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--
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1.8.3.1
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