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Blame SOURCES/kvm-i386-Allow-TOPOEXT-to-be-enabled-on-older-kernels.patch

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From 0a6e593487844fd00920c0caab64aa98eac368a1 Mon Sep 17 00:00:00 2001
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From: Eduardo Habkost <ehabkost@redhat.com>
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Date: Thu, 26 Jul 2018 17:19:04 +0100
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Subject: [PATCH 14/14] i386: Allow TOPOEXT to be enabled on older kernels
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RH-Author: Eduardo Habkost <ehabkost@redhat.com>
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Message-id: <20180726171904.27418-12-ehabkost@redhat.com>
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Patchwork-id: 81534
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O-Subject: [qemu-kvm RHEL8/virt212 PATCH v2 11/11] i386: Allow TOPOEXT to be enabled on older kernels
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Bugzilla: 1597739
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
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From: Babu Moger <babu.moger@amd.com>
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Enabling TOPOEXT feature might cause compatibility issues if
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older kernels does not set this feature. Lets set this feature
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unconditionally.
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Signed-off-by: Babu Moger <babu.moger@amd.com>
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Message-Id: <1528939107-17193-2-git-send-email-babu.moger@amd.com>
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[ehabkost: rewrite comment and commit message]
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Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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(cherry picked from commit f98bbd8304112187cafc3e636c31b2a3865d2717)
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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/kvm.c | 7 +++++++
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 1 file changed, 7 insertions(+)
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diff --git a/target/i386/kvm.c b/target/i386/kvm.c
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index 6e66f9c..bb5e485 100644
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--- a/target/i386/kvm.c
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+++ b/target/i386/kvm.c
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@@ -371,6 +371,13 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function,
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         if (host_tsx_blacklisted()) {
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             ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE);
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         }
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+    } else if (function == 0x80000001 && reg == R_ECX) {
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+        /*
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+         * It's safe to enable TOPOEXT even if it's not returned by
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+         * GET_SUPPORTED_CPUID.  Unconditionally enabling TOPOEXT here allows
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+         * us to keep CPU models including TOPOEXT runnable on older kernels.
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+         */
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+        ret |= CPUID_EXT3_TOPOEXT;
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     } else if (function == 0x80000001 && reg == R_EDX) {
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         /* On Intel, kvm returns cpuid according to the Intel spec,
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          * so add missing bits according to the AMD spec:
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-- 
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1.8.3.1
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