From 7e79bb0dc6af82413c9c5b153f18ce91146e0e53 Mon Sep 17 00:00:00 2001

From: Eduardo Habkost <ehabkost@redhat.com>

Date: Wed, 9 Oct 2019 17:51:39 +0200

Subject: [PATCH 01/10] target-i386: Merge feature filtering/checking functions

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RH-Author: Eduardo Habkost <ehabkost@redhat.com>

Message-id: <20191009175148.1361-2-ehabkost@redhat.com>

Patchwork-id: 91357

O-Subject: [RHEL-7.7.z qemu-kvm PATCH 01/10] target-i386: Merge feature filtering/checking functions

Bugzilla: 1730606

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

RH-Acked-by: Bandan Das <bsd@redhat.com>

RH-Acked-by: Igor Mammedov <imammedo@redhat.com>

Merge filter_features_for_kvm() and kvm_check_features_against_host().

Both functions made exactly the same calculations, the only difference

was that filter_features_for_kvm() changed the bits on cpu->features[],

and kvm_check_features_against_host() did error reporting.

7.8 backport notes (plai):

* unavailable_host_feature() removed due to lack of references.

* report_unavailable_features() from 51f63aed3 to make things compile.

7.7.z backport notes (ehabkost):

* cherry-pick from 7.8 with no conflicts

Reviewed-by: Richard Henderson <rth@twiddle.net>

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

Signed-off-by: Andreas Färber <afaerber@suse.de>

(cherry picked from commit 51f63aed32314479065207ff2fb28255de4dbda4)

Signed-off-by: Paul Lai <plai@redhat.com>

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 target-i386/cpu.c | 91 ++++++++++++++-----------------------------------------

 1 file changed, 22 insertions(+), 69 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c

index c2fcd1e..c9d7557 100644

--- a/target-i386/cpu.c

+++ b/target-i386/cpu.c

@@ -1754,11 +1754,11 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)

 #endif /* CONFIG_KVM */

 }

-static int unavailable_host_feature(FeatureWordInfo *f, uint32_t mask)

+static void report_unavailable_features(FeatureWordInfo *f, uint32_t mask)

 {

     int i;

-    for (i = 0; i < 32; ++i)

+    for (i = 0; i < 32; ++i) {

         if (1 << i & mask) {

             const char *reg = get_register_name_32(f->cpuid_reg);

             assert(reg);

@@ -1767,40 +1767,8 @@ static int unavailable_host_feature(FeatureWordInfo *f, uint32_t mask)

                 f->cpuid_eax, reg,

                 f->feat_names[i] ? "." : "",

                 f->feat_names[i] ? f->feat_names[i] : "", i);

-            break;

-        }

-    return 0;

-}

-

-/* Check if all requested cpu flags are making their way to the guest

- *

- * Returns 0 if all flags are supported by the host, non-zero otherwise.

- *

- * This function may be called only if KVM is enabled.

- */

-static int kvm_check_features_against_host(KVMState *s, X86CPU *cpu)

-{

-    CPUX86State *env = &cpu->env;

-    int rv = 0;

-    FeatureWord w;

-

-    assert(kvm_enabled());

-

-    for (w = 0; w < FEATURE_WORDS; w++) {

-        FeatureWordInfo *wi = &feature_word_info[w];

-        uint32_t guest_feat = env->features[w];

-        uint32_t host_feat = kvm_arch_get_supported_cpuid(s, wi->cpuid_eax,

-                                                             wi->cpuid_ecx,

-                                                             wi->cpuid_reg);

-        uint32_t mask;

-        for (mask = 1; mask; mask <<= 1) {

-            if (guest_feat & mask && !(host_feat & mask)) {

-                unavailable_host_feature(wi, mask);

-                rv = 1;

-            }

         }

     }

-    return rv;

 }

 static void x86_cpuid_version_get_family(Object *obj, Visitor *v, void *opaque,

@@ -2399,12 +2367,21 @@ CpuDefinitionInfoList *arch_query_cpu_definitions(Error **errp)

     return cpu_list;

 }

-#ifdef CONFIG_KVM

-static void filter_features_for_kvm(X86CPU *cpu)

+/*

+ * Filters CPU feature words based on host availability of each feature.

+ *

+ * This function may be called only if KVM is enabled.

+ *

+ * Returns: 0 if all flags are supported by the host, non-zero otherwise.

+ */

+static int filter_features_for_kvm(X86CPU *cpu)

 {

     CPUX86State *env = &cpu->env;

     KVMState *s = kvm_state;

     FeatureWord w;

+    int rv = 0;

+

+    assert(kvm_enabled());

     for (w = 0; w < FEATURE_WORDS; w++) {

         FeatureWordInfo *wi = &feature_word_info[w];

@@ -2414,9 +2391,16 @@ static void filter_features_for_kvm(X86CPU *cpu)

         uint32_t requested_features = env->features[w];

         env->features[w] &= host_feat;

         cpu->filtered_features[w] = requested_features & ~env->features[w];

+        if (cpu->filtered_features[w]) {

+            if (cpu->check_cpuid || cpu->enforce_cpuid) {

+                report_unavailable_features(wi, cpu->filtered_features[w]);

+            }

+            rv = 1;

+        }

     }

+

+    return rv;

 }

-#endif

 static void cpu_x86_register(X86CPU *cpu, const char *name, Error **errp)

 {

@@ -3086,42 +3070,11 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)

             env->features[w] &= feature_word_info[w].tcg_features;

         }

     } else {

-        KVMState *s = kvm_state;

-        if ((cpu->check_cpuid || cpu->enforce_cpuid)

-            && kvm_check_features_against_host(s, cpu) && cpu->enforce_cpuid) {

+        if (filter_features_for_kvm(cpu) && cpu->enforce_cpuid) {

             error_setg(&local_err,

                        "Host's CPU doesn't support requested features");

             goto out;

         }

-#ifdef CONFIG_KVM

-        filter_features_for_kvm(cpu);

-#endif

-    }

-

-    /*

-     * RHEL-only:

-     *

-     * The arch-facilities feature flag is deprecated because it was never

-     * supported upstream.  The upstream property is "arch-capabilities",

-     * but it was not backported to this QEMU version.  Note that

-     * arch-capabilities is not required for mitigation of CVE-2017-5715.

-     *

-     * In addition to being deprecated, arch-facilities blocks live migration

-     * because the value of MSR_IA32_ARCH_CAPABILITIES is host-dependent and

-     * not migration-safe.

-     */

-    if (cpu->env.features[FEAT_7_0_EDX] & CPUID_7_0_EDX_ARCH_CAPABILITIES) {

-        static bool warned = false;

-        static Error *arch_facilities_blocker;

-        if (!warned) {

-            error_setg(&arch_facilities_blocker,

-                       "The arch-facilities CPU feature is deprecated and "

-                       "does not support live migration");

-            migrate_add_blocker(arch_facilities_blocker);

-            error_report("WARNING: the arch-facilities CPU feature is "

-                         "deprecated and does not support live migration");

-            warned = true;

-        }

     }

 #ifndef CONFIG_USER_ONLY

-- 

1.8.3.1