[PATCH v3 0/2] target/arm: Fix using pmu=on on KVM

[PATCH v3 0/2] target/arm: Fix using pmu=on on KVM

[Philippe Mathieu-Daudé]

Since v2:
- include Drew test fix (addressed Peter review comments)
- addressed Drew review comments
- collected R-b/A-b

Andrew Jones (1):
  tests/qtest/arm-cpu-features: Add feature setting tests

Philippe Mathieu-Daudé (1):
  target/arm: Check supported KVM features globally (not per vCPU)

 target/arm/kvm_arm.h           | 21 ++++++++-----------
 target/arm/cpu.c               |  2 +-
 target/arm/cpu64.c             | 10 ++++-----
 target/arm/kvm.c               |  4 ++--
 target/arm/kvm64.c             | 14 +++++--------
 tests/qtest/arm-cpu-features.c | 38 ++++++++++++++++++++++++++++++----
 6 files changed, 56 insertions(+), 33 deletions(-)

-- 
2.21.3

[PATCH v3 1/2] tests/qtest/arm-cpu-features: Add feature setting tests

[Philippe Mathieu-Daudé]

From: Andrew Jones <drjones@redhat.com>

Some cpu features may be enabled and disabled for all configurations
that support the feature. Let's test that.

A recent regression[*] inspired adding these tests.

[*] '-cpu host,pmu=on' caused a segfault

Signed-off-by: Andrew Jones <drjones@redhat.com>
Message-Id: <20200623082310.17577-1-drjones@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 tests/qtest/arm-cpu-features.c | 38 ++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/tests/qtest/arm-cpu-features.c b/tests/qtest/arm-cpu-features.c
index 4692173676..f7e062c189 100644
--- a/tests/qtest/arm-cpu-features.c
+++ b/tests/qtest/arm-cpu-features.c
@@ -159,16 +159,35 @@ static bool resp_get_feature(QDict *resp, const char *feature)
     qobject_unref(_resp);                                              \
 })
 
-#define assert_feature(qts, cpu_type, feature, expected_value)         \
+#define resp_assert_feature(resp, feature, expected_value)             \
 ({                                                                     \
-    QDict *_resp, *_props;                                             \
+    QDict *_props;                                                     \
                                                                        \
-    _resp = do_query_no_props(qts, cpu_type);                          \
     g_assert(_resp);                                                   \
     g_assert(resp_has_props(_resp));                                   \
     _props = resp_get_props(_resp);                                    \
     g_assert(qdict_get(_props, feature));                              \
     g_assert(qdict_get_bool(_props, feature) == (expected_value));     \
+})
+
+#define assert_feature(qts, cpu_type, feature, expected_value)         \
+({                                                                     \
+    QDict *_resp;                                                      \
+                                                                       \
+    _resp = do_query_no_props(qts, cpu_type);                          \
+    g_assert(_resp);                                                   \
+    resp_assert_feature(_resp, feature, expected_value);               \
+    qobject_unref(_resp);                                              \
+})
+
+#define assert_set_feature(qts, cpu_type, feature, value)              \
+({                                                                     \
+    const char *_fmt = (value) ? "{ %s: true }" : "{ %s: false }";     \
+    QDict *_resp;                                                      \
+                                                                       \
+    _resp = do_query(qts, cpu_type, _fmt, feature);                    \
+    g_assert(_resp);                                                   \
+    resp_assert_feature(_resp, feature, value);                        \
     qobject_unref(_resp);                                              \
 })
 
@@ -424,10 +443,14 @@ static void test_query_cpu_model_expansion(const void *data)
     assert_error(qts, "host", "The CPU type 'host' requires KVM", NULL);
 
     /* Test expected feature presence/absence for some cpu types */
-    assert_has_feature_enabled(qts, "max", "pmu");
     assert_has_feature_enabled(qts, "cortex-a15", "pmu");
     assert_has_not_feature(qts, "cortex-a15", "aarch64");
 
+    /* Enabling and disabling pmu should always work. */
+    assert_has_feature_enabled(qts, "max", "pmu");
+    assert_set_feature(qts, "max", "pmu", false);
+    assert_set_feature(qts, "max", "pmu", true);
+
     assert_has_not_feature(qts, "max", "kvm-no-adjvtime");
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
@@ -464,7 +487,10 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         return;
     }
 
+    /* Enabling and disabling kvm-no-adjvtime should always work. */
     assert_has_feature_disabled(qts, "host", "kvm-no-adjvtime");
+    assert_set_feature(qts, "host", "kvm-no-adjvtime", true);
+    assert_set_feature(qts, "host", "kvm-no-adjvtime", false);
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
         bool kvm_supports_sve;
@@ -475,7 +501,11 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         char *error;
 
         assert_has_feature_enabled(qts, "host", "aarch64");
+
+        /* Enabling and disabling pmu should always work. */
         assert_has_feature_enabled(qts, "host", "pmu");
+        assert_set_feature(qts, "host", "pmu", false);
+        assert_set_feature(qts, "host", "pmu", true);
 
         assert_error(qts, "cortex-a15",
             "We cannot guarantee the CPU type 'cortex-a15' works "
-- 
2.21.3

[PATCH v3 2/2] target/arm: Check supported KVM features globally (not per vCPU)

[Philippe Mathieu-Daudé]

Since commit d70c996df23f, when enabling the PMU we get:

  $ qemu-system-aarch64 -cpu host,pmu=on -M virt,accel=kvm,gic-version=3
  Segmentation fault (core dumped)

  Thread 1 "qemu-system-aar" received signal SIGSEGV, Segmentation fault.
  0x0000aaaaaae356d0 in kvm_ioctl (s=0x0, type=44547) at accel/kvm/kvm-all.c:2588
  2588        ret = ioctl(s->fd, type, arg);
  (gdb) bt
  #0  0x0000aaaaaae356d0 in kvm_ioctl (s=0x0, type=44547) at accel/kvm/kvm-all.c:2588
  #1  0x0000aaaaaae31568 in kvm_check_extension (s=0x0, extension=126) at accel/kvm/kvm-all.c:916
  #2  0x0000aaaaaafce254 in kvm_arm_pmu_supported (cpu=0xaaaaac214ab0) at target/arm/kvm.c:213
  #3  0x0000aaaaaafc0f94 in arm_set_pmu (obj=0xaaaaac214ab0, value=true, errp=0xffffffffe438) at target/arm/cpu.c:1111
  #4  0x0000aaaaab5533ac in property_set_bool (obj=0xaaaaac214ab0, v=0xaaaaac223a80, name=0xaaaaac11a970 "pmu", opaque=0xaaaaac222730, errp=0xffffffffe438) at qom/object.c:2170
  #5  0x0000aaaaab5512f0 in object_property_set (obj=0xaaaaac214ab0, v=0xaaaaac223a80, name=0xaaaaac11a970 "pmu", errp=0xffffffffe438) at qom/object.c:1328
  #6  0x0000aaaaab551e10 in object_property_parse (obj=0xaaaaac214ab0, string=0xaaaaac11b4c0 "on", name=0xaaaaac11a970 "pmu", errp=0xffffffffe438) at qom/object.c:1561
  #7  0x0000aaaaab54ee8c in object_apply_global_props (obj=0xaaaaac214ab0, props=0xaaaaac018e20, errp=0xaaaaabd6fd88 <error_fatal>) at qom/object.c:407
  #8  0x0000aaaaab1dd5a4 in qdev_prop_set_globals (dev=0xaaaaac214ab0) at hw/core/qdev-properties.c:1218
  #9  0x0000aaaaab1d9fac in device_post_init (obj=0xaaaaac214ab0) at hw/core/qdev.c:1050
  ...
  #15 0x0000aaaaab54f310 in object_initialize_with_type (obj=0xaaaaac214ab0, size=52208, type=0xaaaaabe237f0) at qom/object.c:512
  #16 0x0000aaaaab54fa24 in object_new_with_type (type=0xaaaaabe237f0) at qom/object.c:687
  #17 0x0000aaaaab54fa80 in object_new (typename=0xaaaaabe23970 "host-arm-cpu") at qom/object.c:702
  #18 0x0000aaaaaaf04a74 in machvirt_init (machine=0xaaaaac0a8550) at hw/arm/virt.c:1770
  #19 0x0000aaaaab1e8720 in machine_run_board_init (machine=0xaaaaac0a8550) at hw/core/machine.c:1138
  #20 0x0000aaaaaaf95394 in qemu_init (argc=5, argv=0xffffffffea58, envp=0xffffffffea88) at softmmu/vl.c:4348
  #21 0x0000aaaaaada3f74 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at softmmu/main.c:48

This is because in frame #2, cpu->kvm_state is still NULL
(the vCPU is not yet realized).

KVM has a hard requirement of all cores supporting the same
feature set. We only need to check if the accelerator supports
a feature, not each vCPU individually.

Fix by removing the 'CPUState *cpu' argument from the
kvm_arm_<FEATURE>_supported() functions.

Fixes: d70c996df23f ('Use CPUState::kvm_state in kvm_arm_pmu_supported')
Reported-by: Haibo Xu <haibo.xu@linaro.org>
Analyzed-by: Andrew Jones <drjones@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 target/arm/kvm_arm.h | 21 +++++++++------------
 target/arm/cpu.c     |  2 +-
 target/arm/cpu64.c   | 10 +++++-----
 target/arm/kvm.c     |  4 ++--
 target/arm/kvm64.c   | 14 +++++---------
 5 files changed, 22 insertions(+), 29 deletions(-)

diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index 48bf5e16d5..a4ce4fd93d 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -269,29 +269,26 @@ void kvm_arm_add_vcpu_properties(Object *obj);
 
 /**
  * kvm_arm_aarch32_supported:
- * @cs: CPUState
  *
- * Returns: true if the KVM VCPU can enable AArch32 mode
+ * Returns: true if KVM can enable AArch32 mode
  * and false otherwise.
  */
-bool kvm_arm_aarch32_supported(CPUState *cs);
+bool kvm_arm_aarch32_supported(void);
 
 /**
  * kvm_arm_pmu_supported:
- * @cs: CPUState
  *
- * Returns: true if the KVM VCPU can enable its PMU
+ * Returns: true if KVM can enable the PMU
  * and false otherwise.
  */
-bool kvm_arm_pmu_supported(CPUState *cs);
+bool kvm_arm_pmu_supported(void);
 
 /**
  * kvm_arm_sve_supported:
- * @cs: CPUState
  *
- * Returns true if the KVM VCPU can enable SVE and false otherwise.
+ * Returns true if KVM can enable SVE and false otherwise.
  */
-bool kvm_arm_sve_supported(CPUState *cs);
+bool kvm_arm_sve_supported(void);
 
 /**
  * kvm_arm_get_max_vm_ipa_size:
@@ -359,17 +356,17 @@ static inline void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
 
 static inline void kvm_arm_add_vcpu_properties(Object *obj) {}
 
-static inline bool kvm_arm_aarch32_supported(CPUState *cs)
+static inline bool kvm_arm_aarch32_supported(void)
 {
     return false;
 }
 
-static inline bool kvm_arm_pmu_supported(CPUState *cs)
+static inline bool kvm_arm_pmu_supported(void)
 {
     return false;
 }
 
-static inline bool kvm_arm_sve_supported(CPUState *cs)
+static inline bool kvm_arm_sve_supported(void)
 {
     return false;
 }
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 5b7a36b5d7..e44e18062c 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1108,7 +1108,7 @@ static void arm_set_pmu(Object *obj, bool value, Error **errp)
     ARMCPU *cpu = ARM_CPU(obj);
 
     if (value) {
-        if (kvm_enabled() && !kvm_arm_pmu_supported(CPU(cpu))) {
+        if (kvm_enabled() && !kvm_arm_pmu_supported()) {
             error_setg(errp, "'pmu' feature not supported by KVM on this host");
             return;
         }
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 778cecc2e6..a0c1d8894b 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -266,7 +266,7 @@ void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp)
 
     /* Collect the set of vector lengths supported by KVM. */
     bitmap_zero(kvm_supported, ARM_MAX_VQ);
-    if (kvm_enabled() && kvm_arm_sve_supported(CPU(cpu))) {
+    if (kvm_enabled() && kvm_arm_sve_supported()) {
         kvm_arm_sve_get_vls(CPU(cpu), kvm_supported);
     } else if (kvm_enabled()) {
         assert(!cpu_isar_feature(aa64_sve, cpu));
@@ -473,7 +473,7 @@ static void cpu_max_set_sve_max_vq(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
+    if (kvm_enabled() && !kvm_arm_sve_supported()) {
         error_setg(errp, "cannot set sve-max-vq");
         error_append_hint(errp, "SVE not supported by KVM on this host\n");
         return;
@@ -519,7 +519,7 @@ static void cpu_arm_set_sve_vq(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (value && kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
+    if (value && kvm_enabled() && !kvm_arm_sve_supported()) {
         error_setg(errp, "cannot enable %s", name);
         error_append_hint(errp, "SVE not supported by KVM on this host\n");
         return;
@@ -556,7 +556,7 @@ static void cpu_arm_set_sve(Object *obj, Visitor *v, const char *name,
         return;
     }
 
-    if (value && kvm_enabled() && !kvm_arm_sve_supported(CPU(cpu))) {
+    if (value && kvm_enabled() && !kvm_arm_sve_supported()) {
         error_setg(errp, "'sve' feature not supported by KVM on this host");
         return;
     }
@@ -751,7 +751,7 @@ static void aarch64_cpu_set_aarch64(Object *obj, bool value, Error **errp)
      * uniform execution state like do_interrupt.
      */
     if (value == false) {
-        if (!kvm_enabled() || !kvm_arm_aarch32_supported(CPU(cpu))) {
+        if (!kvm_enabled() || !kvm_arm_aarch32_supported()) {
             error_setg(errp, "'aarch64' feature cannot be disabled "
                              "unless KVM is enabled and 32-bit EL1 "
                              "is supported");
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index eef3bbd1cc..7c672c78b8 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -208,9 +208,9 @@ void kvm_arm_add_vcpu_properties(Object *obj)
     }
 }
 
-bool kvm_arm_pmu_supported(CPUState *cpu)
+bool kvm_arm_pmu_supported(void)
 {
-    return kvm_check_extension(cpu->kvm_state, KVM_CAP_ARM_PMU_V3);
+    return kvm_check_extension(kvm_state, KVM_CAP_ARM_PMU_V3);
 }
 
 int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index f09ed9f4df..3dc494aaa7 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -652,18 +652,14 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     return true;
 }
 
-bool kvm_arm_aarch32_supported(CPUState *cpu)
+bool kvm_arm_aarch32_supported(void)
 {
-    KVMState *s = KVM_STATE(current_accel());
-
-    return kvm_check_extension(s, KVM_CAP_ARM_EL1_32BIT);
+    return kvm_check_extension(kvm_state, KVM_CAP_ARM_EL1_32BIT);
 }
 
-bool kvm_arm_sve_supported(CPUState *cpu)
+bool kvm_arm_sve_supported(void)
 {
-    KVMState *s = KVM_STATE(current_accel());
-
-    return kvm_check_extension(s, KVM_CAP_ARM_SVE);
+    return kvm_check_extension(kvm_state, KVM_CAP_ARM_SVE);
 }
 
 QEMU_BUILD_BUG_ON(KVM_ARM64_SVE_VQ_MIN != 1);
@@ -798,7 +794,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         env->features &= ~(1ULL << ARM_FEATURE_PMU);
     }
     if (cpu_isar_feature(aa64_sve, cpu)) {
-        assert(kvm_arm_sve_supported(cs));
+        assert(kvm_arm_sve_supported());
         cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_SVE;
     }
 
-- 
2.21.3

Re: [PATCH v3 0/2] target/arm: Fix using pmu=on on KVM

[Andrew Jones]

On Tue, Jun 23, 2020 at 11:06:20AM +0200, Philippe Mathieu-Daudé wrote:
> Since v2:
> - include Drew test fix (addressed Peter review comments)
> - addressed Drew review comments
> - collected R-b/A-b
> 
> Andrew Jones (1):
>   tests/qtest/arm-cpu-features: Add feature setting tests
> 
> Philippe Mathieu-Daudé (1):
>   target/arm: Check supported KVM features globally (not per vCPU)
> 
>  target/arm/kvm_arm.h           | 21 ++++++++-----------
>  target/arm/cpu.c               |  2 +-
>  target/arm/cpu64.c             | 10 ++++-----
>  target/arm/kvm.c               |  4 ++--
>  target/arm/kvm64.c             | 14 +++++--------
>  tests/qtest/arm-cpu-features.c | 38 ++++++++++++++++++++++++++++++----
>  6 files changed, 56 insertions(+), 33 deletions(-)
> 
> -- 
> 2.21.3
> 
>

Hi Phil,

Thanks for including the test patch. To avoid breaking bisection, if one
were to use qtest to bisect something, then the order of patches should
be reversed. I guess Peter can apply them that way without a repost
though.

Thanks,
drew 

Re: [PATCH v3 0/2] target/arm: Fix using pmu=on on KVM

[Peter Maydell]

On Tue, 23 Jun 2020 at 10:18, Andrew Jones <drjones@redhat.com> wrote:
>
> On Tue, Jun 23, 2020 at 11:06:20AM +0200, Philippe Mathieu-Daudé wrote:
> > Since v2:
> > - include Drew test fix (addressed Peter review comments)
> > - addressed Drew review comments
> > - collected R-b/A-b
> >
> > Andrew Jones (1):
> >   tests/qtest/arm-cpu-features: Add feature setting tests
> >
> > Philippe Mathieu-Daudé (1):
> >   target/arm: Check supported KVM features globally (not per vCPU)
> >
> >  target/arm/kvm_arm.h           | 21 ++++++++-----------
> >  target/arm/cpu.c               |  2 +-
> >  target/arm/cpu64.c             | 10 ++++-----
> >  target/arm/kvm.c               |  4 ++--
> >  target/arm/kvm64.c             | 14 +++++--------
> >  tests/qtest/arm-cpu-features.c | 38 ++++++++++++++++++++++++++++++----
> >  6 files changed, 56 insertions(+), 33 deletions(-)
> >
> > --
> > 2.21.3
> >
> >
>
> Hi Phil,
>
> Thanks for including the test patch. To avoid breaking bisection, if one
> were to use qtest to bisect something, then the order of patches should
> be reversed. I guess Peter can apply them that way without a repost
> though.

Yeah, I can just flip the order.

thanks
-- PMM

Re: [PATCH v3 0/2] target/arm: Fix using pmu=on on KVM

[Philippe Mathieu-Daudé]

On 6/23/20 11:19 AM, Peter Maydell wrote:
> On Tue, 23 Jun 2020 at 10:18, Andrew Jones <drjones@redhat.com> wrote:
>>
>> On Tue, Jun 23, 2020 at 11:06:20AM +0200, Philippe Mathieu-Daudé wrote:
>>> Since v2:
>>> - include Drew test fix (addressed Peter review comments)
>>> - addressed Drew review comments
>>> - collected R-b/A-b
>>>
>>> Andrew Jones (1):
>>>   tests/qtest/arm-cpu-features: Add feature setting tests
>>>
>>> Philippe Mathieu-Daudé (1):
>>>   target/arm: Check supported KVM features globally (not per vCPU)
>>>
>>>  target/arm/kvm_arm.h           | 21 ++++++++-----------
>>>  target/arm/cpu.c               |  2 +-
>>>  target/arm/cpu64.c             | 10 ++++-----
>>>  target/arm/kvm.c               |  4 ++--
>>>  target/arm/kvm64.c             | 14 +++++--------
>>>  tests/qtest/arm-cpu-features.c | 38 ++++++++++++++++++++++++++++++----
>>>  6 files changed, 56 insertions(+), 33 deletions(-)
>>>
>>> --
>>> 2.21.3
>>>
>>>
>>
>> Hi Phil,
>>
>> Thanks for including the test patch. To avoid breaking bisection, if one
>> were to use qtest to bisect something, then the order of patches should
>> be reversed.

Oops :)

>> I guess Peter can apply them that way without a repost
>> though.
> 
> Yeah, I can just flip the order.

Thanks both!

Re: [PATCH v3 0/2] target/arm: Fix using pmu=on on KVM

[Peter Maydell]

On Tue, 23 Jun 2020 at 10:06, Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>
> Since v2:
> - include Drew test fix (addressed Peter review comments)
> - addressed Drew review comments
> - collected R-b/A-b
>
> Andrew Jones (1):
>   tests/qtest/arm-cpu-features: Add feature setting tests
>
> Philippe Mathieu-Daudé (1):
>   target/arm: Check supported KVM features globally (not per vCPU)

Applied to target-arm.next, thanks. I dropped the Analyzed-by
tag from one patch because I think we ought to stick to a
standard set of reviewed-by/signed-off-by/acked-by tags.

-- PMM