File 0076-i386-Compensate-for-KVM-SPEC_CTRL-f.patch of Package qemu

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File 0076-i386-Compensate-for-KVM-SPEC_CTRL-f.patch of Package qemu (Revision 604d658cd5408bd2532a95895c023e45)

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From 4e5e2c853977dc27ddab5937e55d181e7f1b5d2a Mon Sep 17 00:00:00 2001
From: Bruce Rogers <brogers@suse.com>
Date: Thu, 22 Feb 2018 04:48:07 -0700
Subject: [PATCH] i386: Compensate for KVM SPEC_CTRL feature availability bug

As we move away from the quick and dirty qemu solution for
Spectre v2, it was found that KVM wasn't reporting the SPEC_CTRL
feature when it in fact was present due to microcode update.
This patch compensates for that bug by checking for the feature
in QEMU code (like the quick and dirty solution did), instead of
simply relying on KVM for that information.
[BR: BSC#1082276]

Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 target/i386/cpu.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index a7e27f3bbf..5c34175f3f 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -2824,6 +2824,14 @@ static uint32_t x86_cpu_get_supported_feature_word(FeatureWord w,
         r = kvm_arch_get_supported_cpuid(kvm_state, wi->cpuid_eax,
                                                     wi->cpuid_ecx,
                                                     wi->cpuid_reg);
+       // BUG!!! We need to compensate for a KVM bug where it doesn't
+       // correctly report support for IBRS (bsc#1082276)
+       if (w == FEAT_7_0_EDX) {
+            uint32_t edx;
+            host_cpuid(7, 0, NULL, NULL, NULL, &edx);
+#define CPUID_7_0_EDX_PRED_CMD (1U << 27)
+           r |= edx & (CPUID_7_0_EDX_SPEC_CTRL | CPUID_7_0_EDX_PRED_CMD);
+       }
     } else if (tcg_enabled()) {
         r = wi->tcg_features;
     } else {

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File 0076-i386-Compensate-for-KVM-SPEC_CTRL-f.patch of Package qemu (Revision 604d658cd5408bd2532a95895c023e45)

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