[Qemu-devel] [QEMU PATCH 0/3] Fix -cpu host and enforce/check to use GET_SUPPORTED_CPUID

[Qemu-devel] [QEMU PATCH 0/3] Fix -cpu host and enforce/check to use GET_SUPPORTED_CPUID

[Eduardo Habkost]

This depends on a previous series I have submitted:
  Subject: [QEMU PATCH 00/15] QEMU KVM_GET_SUPPORTED_CPUID cleanups and fixes
  Message-Id: <1349383747-19383-1-git-send-email-ehabkost@redhat.com>
  http://article.gmane.org/gmane.comp.emulators.kvm.devel/99375

Eduardo Habkost (3):
  target-i385: make cpu_x86_fill_host() void
  target-i386: cpu: make -cpu host/check/enforce code KVM-specific
  target-i386: kvm_cpu_fill_host: use GET_SUPPORTED_CPUID

 target-i386/cpu.c | 52 +++++++++++++++++++++++++++++++++-------------------
 1 file changed, 33 insertions(+), 19 deletions(-)

-- 
1.7.11.7

[Qemu-devel] [QEMU PATCH 1/3] target-i385: make cpu_x86_fill_host() void

[Eduardo Habkost]

The return value of that function is always 0, and is always ignored.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/cpu.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 38fca92..42171c9 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -742,7 +742,7 @@ static int cpu_x86_fill_model_id(char *str)
     return 0;
 }
 
-static int cpu_x86_fill_host(x86_def_t *x86_cpu_def)
+static void cpu_x86_fill_host(x86_def_t *x86_cpu_def)
 {
     uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0;
 
@@ -795,8 +795,6 @@ static int cpu_x86_fill_host(x86_def_t *x86_cpu_def)
      * unsupported ones later.
      */
     x86_cpu_def->svm_features = -1;
-
-    return 0;
 }
 
 static int unavailable_host_feature(struct model_features_t *f, uint32_t mask)
-- 
1.7.11.7

[Qemu-devel] [QEMU PATCH 2/3] target-i386: cpu: make -cpu host/check/enforce code KVM-specific

[Eduardo Habkost]

Rationale:
 * "-cpu host" is available only when using KVM
 * The current implementation of -cpu check/enforce
   (check_features_against_host()) makes sense only when using KVM.

So this makes the functions check_features_against_host() and
cpu_x86_fill_host() KVM-specific, document them as such, and rename them
to kvm_check_features_against_host() and kvm_cpu_fill_host().

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/cpu.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 42171c9..462ccca 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -742,10 +742,17 @@ static int cpu_x86_fill_model_id(char *str)
     return 0;
 }
 
-static void cpu_x86_fill_host(x86_def_t *x86_cpu_def)
+/* Fill a x86_def_t struct with information about the host CPU, and
+ * the CPU features supported by the host hardware + host kernel
+ *
+ * This function may be called only if KVM is enabled.
+ */
+static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
 {
     uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0;
 
+    assert(kvm_enabled());
+
     x86_cpu_def->name = "host";
     host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx);
     x86_cpu_def->level = eax;
@@ -760,7 +767,7 @@ static void cpu_x86_fill_host(x86_def_t *x86_cpu_def)
     x86_cpu_def->ext_features = ecx;
     x86_cpu_def->features = edx;
 
-    if (kvm_enabled() && x86_cpu_def->level >= 7) {
+    if (x86_cpu_def->level >= 7) {
         x86_cpu_def->cpuid_7_0_ebx_features = kvm_arch_get_supported_cpuid(kvm_state, 0x7, 0, R_EBX);
     } else {
         x86_cpu_def->cpuid_7_0_ebx_features = 0;
@@ -815,8 +822,10 @@ static int unavailable_host_feature(struct model_features_t *f, uint32_t mask)
 /* best effort attempt to inform user requested cpu flags aren't making
  * their way to the guest.  Note: ft[].check_feat ideally should be
  * specified via a guest_def field to suppress report of extraneous flags.
+ *
+ * This function may be called only if KVM is enabled.
  */
-static int check_features_against_host(x86_def_t *guest_def)
+static int kvm_check_features_against_host(x86_def_t *guest_def)
 {
     x86_def_t host_def;
     uint32_t mask;
@@ -831,7 +840,9 @@ static int check_features_against_host(x86_def_t *guest_def)
         {&guest_def->ext3_features, &host_def.ext3_features,
             ~CPUID_EXT3_SVM, ext3_feature_name, 0x80000001}};
 
-    cpu_x86_fill_host(&host_def);
+    assert(kvm_enabled());
+
+    kvm_cpu_fill_host(&host_def);
     for (rv = 0, i = 0; i < ARRAY_SIZE(ft); ++i)
         for (mask = 1; mask; mask <<= 1)
             if (ft[i].check_feat & mask && *ft[i].guest_feat & mask &&
@@ -1118,7 +1129,7 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
         if (name && !strcmp(name, def->name))
             break;
     if (kvm_enabled() && name && strcmp(name, "host") == 0) {
-        cpu_x86_fill_host(x86_cpu_def);
+        kvm_cpu_fill_host(x86_cpu_def);
     } else if (!def) {
         goto error;
     } else {
@@ -1268,8 +1279,8 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
     x86_cpu_def->kvm_features &= ~minus_kvm_features;
     x86_cpu_def->svm_features &= ~minus_svm_features;
     x86_cpu_def->cpuid_7_0_ebx_features &= ~minus_7_0_ebx_features;
-    if (check_cpuid) {
-        if (check_features_against_host(x86_cpu_def) && enforce_cpuid)
+    if (check_cpuid && kvm_enabled()) {
+        if (kvm_check_features_against_host(x86_cpu_def) && enforce_cpuid)
             goto error;
     }
     if (x86_cpu_def->cpuid_7_0_ebx_features && x86_cpu_def->level < 7) {
-- 
1.7.11.7

[Qemu-devel] [QEMU PATCH 3/3] target-i386: kvm_cpu_fill_host: use GET_SUPPORTED_CPUID

[Eduardo Habkost]

Change the kvm_cpu_fill_host() function to use
kvm_arch_get_supported_cpuid() instead of running the CPUID instruction
directly, when checking for supported CPUID features.

This should solve two problems at the same time:

 * "-cpu host" was not enabling features that don't need support on
   the host CPU (e.g. x2apic);
 * "check" and "enforce" options were not detecting problems when the
   host CPU did support a feature, but the KVM kernel code didn't
   support it.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/cpu.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 462ccca..4c33fa6 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -749,13 +749,13 @@ static int cpu_x86_fill_model_id(char *str)
  */
 static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
 {
+    KVMState *s = kvm_state;
     uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0;
 
     assert(kvm_enabled());
 
     x86_cpu_def->name = "host";
     host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx);
-    x86_cpu_def->level = eax;
     x86_cpu_def->vendor1 = ebx;
     x86_cpu_def->vendor2 = edx;
     x86_cpu_def->vendor3 = ecx;
@@ -764,21 +764,24 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
     x86_cpu_def->family = ((eax >> 8) & 0x0F) + ((eax >> 20) & 0xFF);
     x86_cpu_def->model = ((eax >> 4) & 0x0F) | ((eax & 0xF0000) >> 12);
     x86_cpu_def->stepping = eax & 0x0F;
-    x86_cpu_def->ext_features = ecx;
-    x86_cpu_def->features = edx;
+
+    x86_cpu_def->level = kvm_arch_get_supported_cpuid(s, 0x0, 0, R_EAX);
+    x86_cpu_def->features = kvm_arch_get_supported_cpuid(s, 0x1, 0, R_EDX);
+    x86_cpu_def->ext_features = kvm_arch_get_supported_cpuid(s, 0x1, 0, R_ECX);
 
     if (x86_cpu_def->level >= 7) {
-        x86_cpu_def->cpuid_7_0_ebx_features = kvm_arch_get_supported_cpuid(kvm_state, 0x7, 0, R_EBX);
+        x86_cpu_def->cpuid_7_0_ebx_features =
+                    kvm_arch_get_supported_cpuid(s, 0x7, 0, R_EBX);
     } else {
         x86_cpu_def->cpuid_7_0_ebx_features = 0;
     }
 
-    host_cpuid(0x80000000, 0, &eax, &ebx, &ecx, &edx);
-    x86_cpu_def->xlevel = eax;
+    x86_cpu_def->xlevel = kvm_arch_get_supported_cpuid(s, 0x80000000, 0, R_EAX);
+    x86_cpu_def->ext2_features =
+                kvm_arch_get_supported_cpuid(s, 0x80000001, 0, R_EDX);
+    x86_cpu_def->ext3_features =
+                kvm_arch_get_supported_cpuid(s, 0x80000001, 0, R_ECX);
 
-    host_cpuid(0x80000001, 0, &eax, &ebx, &ecx, &edx);
-    x86_cpu_def->ext2_features = edx;
-    x86_cpu_def->ext3_features = ecx;
     cpu_x86_fill_model_id(x86_cpu_def->model_id);
     x86_cpu_def->vendor_override = 0;
 
@@ -787,11 +790,13 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
         x86_cpu_def->vendor2 == CPUID_VENDOR_VIA_2 &&
         x86_cpu_def->vendor3 == CPUID_VENDOR_VIA_3) {
         host_cpuid(0xC0000000, 0, &eax, &ebx, &ecx, &edx);
+        eax = kvm_arch_get_supported_cpuid(s, 0xC0000000, 0, R_EAX);
         if (eax >= 0xC0000001) {
             /* Support VIA max extended level */
             x86_cpu_def->xlevel2 = eax;
             host_cpuid(0xC0000001, 0, &eax, &ebx, &ecx, &edx);
-            x86_cpu_def->ext4_features = edx;
+            x86_cpu_def->ext4_features =
+                    kvm_arch_get_supported_cpuid(s, 0xC0000001, 0, R_EDX);
         }
     }
 
-- 
1.7.11.7

Re: [Qemu-devel] [QEMU PATCH 0/3] Fix -cpu host and enforce/check to use GET_SUPPORTED_CPUID

[Marcelo Tosatti]

On Wed, Oct 24, 2012 at 07:44:04PM -0200, Eduardo Habkost wrote:
> This depends on a previous series I have submitted:
>   Subject: [QEMU PATCH 00/15] QEMU KVM_GET_SUPPORTED_CPUID cleanups and fixes
>   Message-Id: <1349383747-19383-1-git-send-email-ehabkost@redhat.com>
>   http://article.gmane.org/gmane.comp.emulators.kvm.devel/99375
> 
> Eduardo Habkost (3):
>   target-i385: make cpu_x86_fill_host() void
>   target-i386: cpu: make -cpu host/check/enforce code KVM-specific
>   target-i386: kvm_cpu_fill_host: use GET_SUPPORTED_CPUID
> 
>  target-i386/cpu.c | 52 +++++++++++++++++++++++++++++++++-------------------
>  1 file changed, 33 insertions(+), 19 deletions(-)
> 
> -- 
> 1.7.11.7

Applied, thanks.