From d4a606b38b5d4b3689b86cc1575908e82179ecfb Mon Sep 17 00:00:00 2001 From: Eduardo Habkost Date: Mon, 27 Mar 2017 11:48:15 -0300 Subject: [PATCH] i386: Don't override -cpu options on -cpu host/max The existing code for "host" and "max" CPU models overrides every single feature in the CPU object at realize time, even the ones that were explicitly enabled or disabled by the user using "feat=on" or "feat=off", while features set using +feat/-feat are kept. This means "-cpu host,+invtsc" works as expected, while "-cpu host,invtsc=on" doesn't. This was a known bug, already documented in a comment inside x86_cpu_expand_features(). What makes this bug worse now is that libvirt 3.0.0 and newer now use "feat=on|off" instead of +feat/-feat when it detects a QEMU version that supports it (see libvirt commit d47db7b16dd5422c7e487c8c8ee5b181a2f9cd66). Change the feature property getter/setter to set a env->user_features field, to keep track of features that were explicitly changed using QOM properties. Then make the max_features code not override user features when handling "-cpu host" and "-cpu max". This will also allow us to remove the plus_features/minus_features hack in the future, but I plan to do that after 2.9.0 is released. Reported-by: Jiri Denemark Signed-off-by: Eduardo Habkost Message-Id: <20170327144815.8043-3-ehabkost@redhat.com> Reviewed-by: Igor Mammedov Tested-by: Jiri Denemark Signed-off-by: Eduardo Habkost --- target/i386/cpu.c | 13 +++++++++---- target/i386/cpu.h | 2 ++ 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index feefa5b8a451..13c0985f110a 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -3373,15 +3373,19 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp) GList *l; Error *local_err = NULL; - /*TODO: cpu->max_features incorrectly overwrites features - * set using "feat=on|off". Once we fix this, we can convert + /*TODO: Now cpu->max_features doesn't overwrite features + * set using QOM properties, and we can convert * plus_features & minus_features to global properties * inside x86_cpu_parse_featurestr() too. */ if (cpu->max_features) { for (w = 0; w < FEATURE_WORDS; w++) { - env->features[w] = - x86_cpu_get_supported_feature_word(w, cpu->migratable); + /* Override only features that weren't set explicitly + * by the user. + */ + env->features[w] |= + x86_cpu_get_supported_feature_word(w, cpu->migratable) & + ~env->user_features[w]; } } @@ -3731,6 +3735,7 @@ static void x86_cpu_set_bit_prop(Object *obj, Visitor *v, const char *name, } else { cpu->env.features[fp->w] &= ~fp->mask; } + cpu->env.user_features[fp->w] |= fp->mask; } static void x86_cpu_release_bit_prop(Object *obj, const char *name, diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 07401ad9fed5..c4602ca80dde 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1147,6 +1147,8 @@ typedef struct CPUX86State { uint32_t cpuid_vendor3; uint32_t cpuid_version; FeatureWordArray features; + /* Features that were explicitly enabled/disabled */ + FeatureWordArray user_features; uint32_t cpuid_model[12]; /* MTRRs */