[PATCH v4 0/6] hw/arm/virt: Introduce kvm-steal-time

[PATCH v4 0/6] hw/arm/virt: Introduce kvm-steal-time

[Andrew Jones]

v4:
  - Rebased to latest master
  - Added an official linux header synch patch, replacing the
    hack patch used in v3
  - Added a patch to restore the arm-cpu-features test for AArch64
    that got lost in the meson shuffle
  - Added Eric's R-b's

v3:
  - Rebased: 5.2 machine type and kvm32 drop now included
  - Switched to using new KVM cap that has been merged upstream
  - Picked up some r-b's and some of Eric's comments from v2

v2: https://www.mail-archive.com/qemu-devel@nongnu.org/msg727588.html

KVM supports the ability to publish the amount of time that VCPUs
were runnable, but not running due to other host threads running
instead, to the guest. The guest scheduler may use that information
when making decisions and the guest may expose it to its userspace
(Linux publishes this information in /proc/stat). This feature is
called "steal time" as it represents the amount of time stolen from
a guest by scheduling out its VCPUs. To enable this feature KVM
userspace must provide a memory region that will be used to publish
the information to the guest. The memory region is typical migratable
region. The GPA of the region is given to KVM through a VCPU device
ioctl interface. This feature is only available for 64-bit guests
per the Arm PVTIME specification (DEN0057A).

This series provides the QEMU support of this feature. It will
be enabled by default for 5.2 machine types and later, but may
be disabled with a new CPU property "kvm-steal-time".

Thanks,
drew


Andrew Jones (6):
  linux headers: sync to 5.9-rc7
  target/arm/kvm: Make uncalled stubs explicitly unreachable
  hw/arm/virt: Move post cpu realize check into its own function
  hw/arm/virt: Move kvm pmu setup to virt_cpu_post_init
  tests/qtest: Restore aarch64 arm-cpu-features test
  hw/arm/virt: Implement kvm-steal-time

 docs/system/arm/cpu-features.rst |  11 ++++
 hw/arm/virt.c                    | 110 ++++++++++++++++++++++---------
 include/hw/arm/virt.h            |   5 ++
 linux-headers/linux/kvm.h        |   6 +-
 target/arm/cpu.c                 |   8 +++
 target/arm/cpu.h                 |   4 ++
 target/arm/kvm.c                 |  16 +++++
 target/arm/kvm64.c               |  64 ++++++++++++++++--
 target/arm/kvm_arm.h             |  94 ++++++++++++++++++++------
 target/arm/monitor.c             |   2 +-
 tests/qtest/arm-cpu-features.c   |  25 +++++--
 tests/qtest/meson.build          |   3 +-
 12 files changed, 286 insertions(+), 62 deletions(-)

-- 
2.26.2

[PATCH v4 1/6] linux headers: sync to 5.9-rc7

[Andrew Jones]

Update against Linux 5.9-rc7.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 linux-headers/linux/kvm.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
index 6683e2e1b0a0..43580c767c33 100644
--- a/linux-headers/linux/kvm.h
+++ b/linux-headers/linux/kvm.h
@@ -790,9 +790,10 @@ struct kvm_ppc_resize_hpt {
 #define KVM_VM_PPC_HV 1
 #define KVM_VM_PPC_PR 2
 
-/* on MIPS, 0 forces trap & emulate, 1 forces VZ ASE */
-#define KVM_VM_MIPS_TE		0
+/* on MIPS, 0 indicates auto, 1 forces VZ ASE, 2 forces trap & emulate */
+#define KVM_VM_MIPS_AUTO	0
 #define KVM_VM_MIPS_VZ		1
+#define KVM_VM_MIPS_TE		2
 
 #define KVM_S390_SIE_PAGE_OFFSET 1
 
@@ -1035,6 +1036,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_LAST_CPU 184
 #define KVM_CAP_SMALLER_MAXPHYADDR 185
 #define KVM_CAP_S390_DIAG318 186
+#define KVM_CAP_STEAL_TIME 187
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.26.2

[PATCH v4 2/6] target/arm/kvm: Make uncalled stubs explicitly unreachable

[Andrew Jones]

When we compile without KVM support !defined(CONFIG_KVM) we generate
stubs for functions that the linker will still encounter. Sometimes
these stubs can be executed safely and are placed in paths where they
get executed with or without KVM. Other functions should never be
called without KVM. Those functions should be guarded by kvm_enabled(),
but should also be robust to refactoring mistakes. Putting a
g_assert_not_reached() in the function should help. Additionally,
the g_assert_not_reached() calls may actually help the linker remove
some code.

We remove the stubs for kvm_arm_get/put_virtual_time(), as they aren't
necessary at all - the only caller is in kvm.c

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 target/arm/kvm_arm.h | 51 +++++++++++++++++++++++++++-----------------
 1 file changed, 32 insertions(+), 19 deletions(-)

diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index bc178eeb84c0..f513702176a7 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -344,18 +344,10 @@ int kvm_arm_set_irq(int cpu, int irqtype, int irq, int level);
 
 #else
 
-static inline void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
-{
-    /*
-     * This should never actually be called in the "not KVM" case,
-     * but set up the fields to indicate an error anyway.
-     */
-    cpu->kvm_target = QEMU_KVM_ARM_TARGET_NONE;
-    cpu->host_cpu_probe_failed = true;
-}
-
-static inline void kvm_arm_add_vcpu_properties(Object *obj) {}
-
+/*
+ * It's safe to call these functions without KVM support.
+ * They should either do nothing or return "not supported".
+ */
 static inline bool kvm_arm_aarch32_supported(void)
 {
     return false;
@@ -371,23 +363,44 @@ static inline bool kvm_arm_sve_supported(void)
     return false;
 }
 
+/*
+ * These functions should never actually be called without KVM support.
+ */
+static inline void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
+{
+    g_assert_not_reached();
+}
+
+static inline void kvm_arm_add_vcpu_properties(Object *obj)
+{
+    g_assert_not_reached();
+}
+
 static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
 {
-    return -ENOENT;
+    g_assert_not_reached();
 }
 
 static inline int kvm_arm_vgic_probe(void)
 {
-    return 0;
+    g_assert_not_reached();
 }
 
-static inline void kvm_arm_pmu_set_irq(CPUState *cs, int irq) {}
-static inline void kvm_arm_pmu_init(CPUState *cs) {}
+static inline void kvm_arm_pmu_set_irq(CPUState *cs, int irq)
+{
+    g_assert_not_reached();
+}
 
-static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map) {}
+static inline void kvm_arm_pmu_init(CPUState *cs)
+{
+    g_assert_not_reached();
+}
+
+static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map)
+{
+    g_assert_not_reached();
+}
 
-static inline void kvm_arm_get_virtual_time(CPUState *cs) {}
-static inline void kvm_arm_put_virtual_time(CPUState *cs) {}
 #endif
 
 static inline const char *gic_class_name(void)
-- 
2.26.2

[PATCH v4 3/6] hw/arm/virt: Move post cpu realize check into its own function

[Andrew Jones]

We'll add more to this new function in coming patches so we also
state the gic must be created and call it below create_gic().

No functional change intended.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 hw/arm/virt.c | 43 +++++++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 1231a197c850..524eafe22df8 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1672,6 +1672,31 @@ static void finalize_gic_version(VirtMachineState *vms)
     }
 }
 
+/*
+ * virt_cpu_post_init() must be called after the CPUs have
+ * been realized and the GIC has been created.
+ */
+static void virt_cpu_post_init(VirtMachineState *vms)
+{
+    bool aarch64;
+
+    aarch64 = object_property_get_bool(OBJECT(first_cpu), "aarch64", NULL);
+
+    if (!kvm_enabled()) {
+        if (aarch64 && vms->highmem) {
+            int requested_pa_size = 64 - clz64(vms->highest_gpa);
+            int pamax = arm_pamax(ARM_CPU(first_cpu));
+
+            if (pamax < requested_pa_size) {
+                error_report("VCPU supports less PA bits (%d) than "
+                             "requested by the memory map (%d)",
+                             pamax, requested_pa_size);
+                exit(1);
+            }
+        }
+    }
+}
+
 static void machvirt_init(MachineState *machine)
 {
     VirtMachineState *vms = VIRT_MACHINE(machine);
@@ -1886,22 +1911,6 @@ static void machvirt_init(MachineState *machine)
     fdt_add_timer_nodes(vms);
     fdt_add_cpu_nodes(vms);
 
-   if (!kvm_enabled()) {
-        ARMCPU *cpu = ARM_CPU(first_cpu);
-        bool aarch64 = object_property_get_bool(OBJECT(cpu), "aarch64", NULL);
-
-        if (aarch64 && vms->highmem) {
-            int requested_pa_size, pamax = arm_pamax(cpu);
-
-            requested_pa_size = 64 - clz64(vms->highest_gpa);
-            if (pamax < requested_pa_size) {
-                error_report("VCPU supports less PA bits (%d) than requested "
-                            "by the memory map (%d)", pamax, requested_pa_size);
-                exit(1);
-            }
-        }
-    }
-
     memory_region_add_subregion(sysmem, vms->memmap[VIRT_MEM].base,
                                 machine->ram);
     if (machine->device_memory) {
@@ -1913,6 +1922,8 @@ static void machvirt_init(MachineState *machine)
 
     create_gic(vms);
 
+    virt_cpu_post_init(vms);
+
     fdt_add_pmu_nodes(vms);
 
     create_uart(vms, VIRT_UART, sysmem, serial_hd(0));
-- 
2.26.2

[PATCH v4 4/6] hw/arm/virt: Move kvm pmu setup to virt_cpu_post_init

[Andrew Jones]

Move the KVM PMU setup part of fdt_add_pmu_nodes() to
virt_cpu_post_init(), which is a more appropriate location. Now
fdt_add_pmu_nodes() is also named more appropriately, because it
no longer does anything but fdt node creation.

No functional change intended.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 hw/arm/virt.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 524eafe22df8..92ab0fd094dc 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -521,21 +521,12 @@ static void fdt_add_gic_node(VirtMachineState *vms)
 
 static void fdt_add_pmu_nodes(const VirtMachineState *vms)
 {
-    CPUState *cpu;
-    ARMCPU *armcpu;
+    ARMCPU *armcpu = ARM_CPU(first_cpu);
     uint32_t irqflags = GIC_FDT_IRQ_FLAGS_LEVEL_HI;
 
-    CPU_FOREACH(cpu) {
-        armcpu = ARM_CPU(cpu);
-        if (!arm_feature(&armcpu->env, ARM_FEATURE_PMU)) {
-            return;
-        }
-        if (kvm_enabled()) {
-            if (kvm_irqchip_in_kernel()) {
-                kvm_arm_pmu_set_irq(cpu, PPI(VIRTUAL_PMU_IRQ));
-            }
-            kvm_arm_pmu_init(cpu);
-        }
+    if (!arm_feature(&armcpu->env, ARM_FEATURE_PMU)) {
+        assert(!object_property_get_bool(OBJECT(armcpu), "pmu", NULL));
+        return;
     }
 
     if (vms->gic_version == VIRT_GIC_VERSION_2) {
@@ -544,7 +535,6 @@ static void fdt_add_pmu_nodes(const VirtMachineState *vms)
                              (1 << vms->smp_cpus) - 1);
     }
 
-    armcpu = ARM_CPU(qemu_get_cpu(0));
     qemu_fdt_add_subnode(vms->fdt, "/pmu");
     if (arm_feature(&armcpu->env, ARM_FEATURE_V8)) {
         const char compat[] = "arm,armv8-pmuv3";
@@ -1678,11 +1668,23 @@ static void finalize_gic_version(VirtMachineState *vms)
  */
 static void virt_cpu_post_init(VirtMachineState *vms)
 {
-    bool aarch64;
+    bool aarch64, pmu;
+    CPUState *cpu;
 
     aarch64 = object_property_get_bool(OBJECT(first_cpu), "aarch64", NULL);
+    pmu = object_property_get_bool(OBJECT(first_cpu), "pmu", NULL);
 
-    if (!kvm_enabled()) {
+    if (kvm_enabled()) {
+        CPU_FOREACH(cpu) {
+            if (pmu) {
+                assert(arm_feature(&ARM_CPU(cpu)->env, ARM_FEATURE_PMU));
+                if (kvm_irqchip_in_kernel()) {
+                    kvm_arm_pmu_set_irq(cpu, PPI(VIRTUAL_PMU_IRQ));
+                }
+                kvm_arm_pmu_init(cpu);
+            }
+        }
+    } else {
         if (aarch64 && vms->highmem) {
             int requested_pa_size = 64 - clz64(vms->highest_gpa);
             int pamax = arm_pamax(ARM_CPU(first_cpu));
-- 
2.26.2

[PATCH v4 5/6] tests/qtest: Restore aarch64 arm-cpu-features test

[Andrew Jones]

arm-cpu-features got dropped from the AArch64 tests during the meson
conversion shuffle.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 tests/qtest/meson.build | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 874b5be62be2..db169a53b530 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -146,7 +146,8 @@ qtests_aarch64 = \
   (cpu != 'arm' ? ['bios-tables-test'] : []) +                                                  \
   (config_all_devices.has_key('CONFIG_TPM_TIS_SYSBUS') ? ['tpm-tis-device-test'] : []) +        \
   (config_all_devices.has_key('CONFIG_TPM_TIS_SYSBUS') ? ['tpm-tis-device-swtpm-test'] : []) +  \
-  ['numa-test',
+  ['arm-cpu-features',
+   'numa-test',
    'boot-serial-test',
    'migration-test']
 
-- 
2.26.2

[PATCH v4 6/6] hw/arm/virt: Implement kvm-steal-time

[Andrew Jones]

We add the kvm-steal-time CPU property and implement it for machvirt.
A tiny bit of refactoring was also done to allow pmu and pvtime to
use the same vcpu device helper functions.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 docs/system/arm/cpu-features.rst | 11 ++++++
 hw/arm/virt.c                    | 43 +++++++++++++++++++--
 include/hw/arm/virt.h            |  5 +++
 target/arm/cpu.c                 |  8 ++++
 target/arm/cpu.h                 |  4 ++
 target/arm/kvm.c                 | 16 ++++++++
 target/arm/kvm64.c               | 64 +++++++++++++++++++++++++++++---
 target/arm/kvm_arm.h             | 43 +++++++++++++++++++++
 target/arm/monitor.c             |  2 +-
 tests/qtest/arm-cpu-features.c   | 25 +++++++++++--
 10 files changed, 208 insertions(+), 13 deletions(-)

diff --git a/docs/system/arm/cpu-features.rst b/docs/system/arm/cpu-features.rst
index 2d5c06cd016b..35196a6b759d 100644
--- a/docs/system/arm/cpu-features.rst
+++ b/docs/system/arm/cpu-features.rst
@@ -200,6 +200,17 @@ the list of KVM VCPU features and their descriptions.
                            adjustment, also restoring the legacy (pre-5.0)
                            behavior.
 
+  kvm-steal-time           Since v5.2, kvm-steal-time is enabled by
+                           default when KVM is enabled, the feature is
+                           supported, and the guest is 64-bit.
+
+                           When kvm-steal-time is enabled a 64-bit guest
+                           can account for time its CPUs were not running
+                           due to the host not scheduling the corresponding
+                           VCPU threads.  The accounting statistics may
+                           influence the guest scheduler behavior and/or be
+                           exposed to the guest userspace.
+
 SVE CPU Properties
 ==================
 
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 92ab0fd094dc..d5095046315a 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -151,6 +151,7 @@ static const MemMapEntry base_memmap[] = {
     [VIRT_PCDIMM_ACPI] =        { 0x09070000, MEMORY_HOTPLUG_IO_LEN },
     [VIRT_ACPI_GED] =           { 0x09080000, ACPI_GED_EVT_SEL_LEN },
     [VIRT_NVDIMM_ACPI] =        { 0x09090000, NVDIMM_ACPI_IO_LEN},
+    [VIRT_PVTIME] =             { 0x090a0000, 0x00010000 },
     [VIRT_MMIO] =               { 0x0a000000, 0x00000200 },
     /* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that size */
     [VIRT_PLATFORM_BUS] =       { 0x0c000000, 0x02000000 },
@@ -1666,15 +1667,39 @@ static void finalize_gic_version(VirtMachineState *vms)
  * virt_cpu_post_init() must be called after the CPUs have
  * been realized and the GIC has been created.
  */
-static void virt_cpu_post_init(VirtMachineState *vms)
+static void virt_cpu_post_init(VirtMachineState *vms, int max_cpus,
+                               MemoryRegion *sysmem)
 {
-    bool aarch64, pmu;
+    bool aarch64, pmu, steal_time;
     CPUState *cpu;
 
     aarch64 = object_property_get_bool(OBJECT(first_cpu), "aarch64", NULL);
     pmu = object_property_get_bool(OBJECT(first_cpu), "pmu", NULL);
+    steal_time = object_property_get_bool(OBJECT(first_cpu),
+                                          "kvm-steal-time", NULL);
 
     if (kvm_enabled()) {
+        hwaddr pvtime_reg_base = vms->memmap[VIRT_PVTIME].base;
+        hwaddr pvtime_reg_size = vms->memmap[VIRT_PVTIME].size;
+
+        if (steal_time) {
+            MemoryRegion *pvtime = g_new(MemoryRegion, 1);
+            hwaddr pvtime_size = max_cpus * PVTIME_SIZE_PER_CPU;
+
+            /* The memory region size must be a multiple of host page size. */
+            pvtime_size = REAL_HOST_PAGE_ALIGN(pvtime_size);
+
+            if (pvtime_size > pvtime_reg_size) {
+                error_report("pvtime requires a %ld byte memory region for "
+                             "%d CPUs, but only %ld has been reserved",
+                             pvtime_size, max_cpus, pvtime_reg_size);
+                exit(1);
+            }
+
+            memory_region_init_ram(pvtime, NULL, "pvtime", pvtime_size, NULL);
+            memory_region_add_subregion(sysmem, pvtime_reg_base, pvtime);
+        }
+
         CPU_FOREACH(cpu) {
             if (pmu) {
                 assert(arm_feature(&ARM_CPU(cpu)->env, ARM_FEATURE_PMU));
@@ -1683,6 +1708,10 @@ static void virt_cpu_post_init(VirtMachineState *vms)
                 }
                 kvm_arm_pmu_init(cpu);
             }
+            if (steal_time) {
+                kvm_arm_pvtime_init(cpu, pvtime_reg_base +
+                                         cpu->cpu_index * PVTIME_SIZE_PER_CPU);
+            }
         }
     } else {
         if (aarch64 && vms->highmem) {
@@ -1853,6 +1882,11 @@ static void machvirt_init(MachineState *machine)
             object_property_set_bool(cpuobj, "kvm-no-adjvtime", true, NULL);
         }
 
+        if (vmc->no_kvm_steal_time &&
+            object_property_find(cpuobj, "kvm-steal-time")) {
+            object_property_set_bool(cpuobj, "kvm-steal-time", false, NULL);
+        }
+
         if (vmc->no_pmu && object_property_find(cpuobj, "pmu")) {
             object_property_set_bool(cpuobj, "pmu", false, NULL);
         }
@@ -1924,7 +1958,7 @@ static void machvirt_init(MachineState *machine)
 
     create_gic(vms);
 
-    virt_cpu_post_init(vms);
+    virt_cpu_post_init(vms, possible_cpus->len, sysmem);
 
     fdt_add_pmu_nodes(vms);
 
@@ -2566,8 +2600,11 @@ DEFINE_VIRT_MACHINE_AS_LATEST(5, 2)
 
 static void virt_machine_5_1_options(MachineClass *mc)
 {
+    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(OBJECT_CLASS(mc));
+
     virt_machine_5_2_options(mc);
     compat_props_add(mc->compat_props, hw_compat_5_1, hw_compat_5_1_len);
+    vmc->no_kvm_steal_time = true;
 }
 DEFINE_VIRT_MACHINE(5, 1)
 
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index d018a4f29788..3151fc93428a 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -54,6 +54,9 @@
 
 #define PPI(irq) ((irq) + 16)
 
+/* See Linux kernel arch/arm64/include/asm/pvclock-abi.h */
+#define PVTIME_SIZE_PER_CPU 64
+
 enum {
     VIRT_FLASH,
     VIRT_MEM,
@@ -81,6 +84,7 @@ enum {
     VIRT_PCDIMM_ACPI,
     VIRT_ACPI_GED,
     VIRT_NVDIMM_ACPI,
+    VIRT_PVTIME,
     VIRT_LOWMEMMAP_LAST,
 };
 
@@ -126,6 +130,7 @@ struct VirtMachineClass {
     bool no_highmem_ecam;
     bool no_ged;   /* Machines < 4.2 has no support for ACPI GED device */
     bool kvm_no_adjvtime;
+    bool no_kvm_steal_time;
     bool acpi_expose_flash;
 };
 
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index a7643deab411..923903f1b52c 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1310,6 +1310,14 @@ void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp)
             return;
         }
     }
+
+    if (kvm_enabled()) {
+        kvm_arm_steal_time_finalize(cpu, &local_err);
+        if (local_err != NULL) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
 }
 
 static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 6036f61d60b3..dcabd6ce2d97 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -24,6 +24,7 @@
 #include "hw/registerfields.h"
 #include "cpu-qom.h"
 #include "exec/cpu-defs.h"
+#include "qapi/qapi-types-common.h"
 
 /* ARM processors have a weak memory model */
 #define TCG_GUEST_DEFAULT_MO      (0)
@@ -863,6 +864,9 @@ struct ARMCPU {
     bool kvm_vtime_dirty;
     uint64_t kvm_vtime;
 
+    /* KVM steal time */
+    OnOffAuto kvm_steal_time;
+
     /* Uniprocessor system with MP extensions */
     bool mp_is_up;
 
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 0dcb9bfe137d..ffe186de8d19 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -192,6 +192,16 @@ static void kvm_no_adjvtime_set(Object *obj, bool value, Error **errp)
     ARM_CPU(obj)->kvm_adjvtime = !value;
 }
 
+static bool kvm_steal_time_get(Object *obj, Error **errp)
+{
+    return ARM_CPU(obj)->kvm_steal_time != ON_OFF_AUTO_OFF;
+}
+
+static void kvm_steal_time_set(Object *obj, bool value, Error **errp)
+{
+    ARM_CPU(obj)->kvm_steal_time = value ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
+}
+
 /* KVM VCPU properties should be prefixed with "kvm-". */
 void kvm_arm_add_vcpu_properties(Object *obj)
 {
@@ -207,6 +217,12 @@ void kvm_arm_add_vcpu_properties(Object *obj)
                                         "the virtual counter. VM stopped time "
                                         "will be counted.");
     }
+
+    cpu->kvm_steal_time = ON_OFF_AUTO_AUTO;
+    object_property_add_bool(obj, "kvm-steal-time", kvm_steal_time_get,
+                             kvm_steal_time_set);
+    object_property_set_description(obj, "kvm-steal-time",
+                                    "Set off to disable KVM steal time.");
 }
 
 bool kvm_arm_pmu_supported(void)
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index 987b35e33fea..92768166809d 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -17,6 +17,7 @@
 #include <linux/kvm.h>
 
 #include "qemu-common.h"
+#include "qapi/error.h"
 #include "cpu.h"
 #include "qemu/timer.h"
 #include "qemu/error-report.h"
@@ -397,19 +398,20 @@ static CPUWatchpoint *find_hw_watchpoint(CPUState *cpu, target_ulong addr)
     return NULL;
 }
 
-static bool kvm_arm_pmu_set_attr(CPUState *cs, struct kvm_device_attr *attr)
+static bool kvm_arm_set_device_attr(CPUState *cs, struct kvm_device_attr *attr,
+                                    const char *name)
 {
     int err;
 
     err = kvm_vcpu_ioctl(cs, KVM_HAS_DEVICE_ATTR, attr);
     if (err != 0) {
-        error_report("PMU: KVM_HAS_DEVICE_ATTR: %s", strerror(-err));
+        error_report("%s: KVM_HAS_DEVICE_ATTR: %s", name, strerror(-err));
         return false;
     }
 
     err = kvm_vcpu_ioctl(cs, KVM_SET_DEVICE_ATTR, attr);
     if (err != 0) {
-        error_report("PMU: KVM_SET_DEVICE_ATTR: %s", strerror(-err));
+        error_report("%s: KVM_SET_DEVICE_ATTR: %s", name, strerror(-err));
         return false;
     }
 
@@ -426,7 +428,7 @@ void kvm_arm_pmu_init(CPUState *cs)
     if (!ARM_CPU(cs)->has_pmu) {
         return;
     }
-    if (!kvm_arm_pmu_set_attr(cs, &attr)) {
+    if (!kvm_arm_set_device_attr(cs, &attr, "PMU")) {
         error_report("failed to init PMU");
         abort();
     }
@@ -443,12 +445,29 @@ void kvm_arm_pmu_set_irq(CPUState *cs, int irq)
     if (!ARM_CPU(cs)->has_pmu) {
         return;
     }
-    if (!kvm_arm_pmu_set_attr(cs, &attr)) {
+    if (!kvm_arm_set_device_attr(cs, &attr, "PMU")) {
         error_report("failed to set irq for PMU");
         abort();
     }
 }
 
+void kvm_arm_pvtime_init(CPUState *cs, uint64_t ipa)
+{
+    struct kvm_device_attr attr = {
+        .group = KVM_ARM_VCPU_PVTIME_CTRL,
+        .attr = KVM_ARM_VCPU_PVTIME_IPA,
+        .addr = (uint64_t)&ipa,
+    };
+
+    if (ARM_CPU(cs)->kvm_steal_time == ON_OFF_AUTO_OFF) {
+        return;
+    }
+    if (!kvm_arm_set_device_attr(cs, &attr, "PVTIME IPA")) {
+        error_report("failed to init PVTIME IPA");
+        abort();
+    }
+}
+
 static int read_sys_reg32(int fd, uint32_t *pret, uint64_t id)
 {
     uint64_t ret;
@@ -651,6 +670,36 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     return true;
 }
 
+void kvm_arm_steal_time_finalize(ARMCPU *cpu, Error **errp)
+{
+    bool has_steal_time = kvm_arm_steal_time_supported();
+
+    if (cpu->kvm_steal_time == ON_OFF_AUTO_AUTO) {
+        if (!has_steal_time || !arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
+            cpu->kvm_steal_time = ON_OFF_AUTO_OFF;
+        } else {
+            cpu->kvm_steal_time = ON_OFF_AUTO_ON;
+        }
+    } else if (cpu->kvm_steal_time == ON_OFF_AUTO_ON) {
+        if (!has_steal_time) {
+            error_setg(errp, "'kvm-steal-time' cannot be enabled "
+                             "on this host");
+            return;
+        } else if (!arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
+            /*
+             * DEN0057A chapter 2 says "This specification only covers
+             * systems in which the Execution state of the hypervisor
+             * as well as EL1 of virtual machines is AArch64.". And,
+             * to ensure that, the smc/hvc calls are only specified as
+             * smc64/hvc64.
+             */
+            error_setg(errp, "'kvm-steal-time' cannot be enabled "
+                             "for AArch32 guests");
+            return;
+        }
+    }
+}
+
 bool kvm_arm_aarch32_supported(void)
 {
     return kvm_check_extension(kvm_state, KVM_CAP_ARM_EL1_32BIT);
@@ -661,6 +710,11 @@ bool kvm_arm_sve_supported(void)
     return kvm_check_extension(kvm_state, KVM_CAP_ARM_SVE);
 }
 
+bool kvm_arm_steal_time_supported(void)
+{
+    return kvm_check_extension(kvm_state, KVM_CAP_STEAL_TIME);
+}
+
 QEMU_BUILD_BUG_ON(KVM_ARM64_SVE_VQ_MIN != 1);
 
 void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map)
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index f513702176a7..eb81b7059eb1 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -267,6 +267,24 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu);
  */
 void kvm_arm_add_vcpu_properties(Object *obj);
 
+/**
+ * kvm_arm_steal_time_finalize:
+ * @cpu: ARMCPU for which to finalize kvm-steal-time
+ * @errp: Pointer to Error* for error propagation
+ *
+ * Validate the kvm-steal-time property selection and set its default
+ * based on KVM support and guest configuration.
+ */
+void kvm_arm_steal_time_finalize(ARMCPU *cpu, Error **errp);
+
+/**
+ * kvm_arm_steal_time_supported:
+ *
+ * Returns: true if KVM can enable steal time reporting
+ * and false otherwise.
+ */
+bool kvm_arm_steal_time_supported(void);
+
 /**
  * kvm_arm_aarch32_supported:
  *
@@ -340,6 +358,16 @@ int kvm_arm_vgic_probe(void);
 
 void kvm_arm_pmu_set_irq(CPUState *cs, int irq);
 void kvm_arm_pmu_init(CPUState *cs);
+
+/**
+ * kvm_arm_pvtime_init:
+ * @cs: CPUState
+ * @ipa: Per-vcpu guest physical base address of the pvtime structures
+ *
+ * Initializes PVTIME for the VCPU, setting the PVTIME IPA to @ipa.
+ */
+void kvm_arm_pvtime_init(CPUState *cs, uint64_t ipa);
+
 int kvm_arm_set_irq(int cpu, int irqtype, int irq, int level);
 
 #else
@@ -363,6 +391,11 @@ static inline bool kvm_arm_sve_supported(void)
     return false;
 }
 
+static inline bool kvm_arm_steal_time_supported(void)
+{
+    return false;
+}
+
 /*
  * These functions should never actually be called without KVM support.
  */
@@ -396,6 +429,16 @@ static inline void kvm_arm_pmu_init(CPUState *cs)
     g_assert_not_reached();
 }
 
+static inline void kvm_arm_pvtime_init(CPUState *cs, uint64_t ipa)
+{
+    g_assert_not_reached();
+}
+
+static inline void kvm_arm_steal_time_finalize(ARMCPU *cpu, Error **errp)
+{
+    g_assert_not_reached();
+}
+
 static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map)
 {
     g_assert_not_reached();
diff --git a/target/arm/monitor.c b/target/arm/monitor.c
index 375f34bfaa76..169d8a64b651 100644
--- a/target/arm/monitor.c
+++ b/target/arm/monitor.c
@@ -103,7 +103,7 @@ static const char *cpu_model_advertised_features[] = {
     "sve128", "sve256", "sve384", "sve512",
     "sve640", "sve768", "sve896", "sve1024", "sve1152", "sve1280",
     "sve1408", "sve1536", "sve1664", "sve1792", "sve1920", "sve2048",
-    "kvm-no-adjvtime",
+    "kvm-no-adjvtime", "kvm-steal-time",
     NULL
 };
 
diff --git a/tests/qtest/arm-cpu-features.c b/tests/qtest/arm-cpu-features.c
index 77b5e30a9cf5..d20094d5a709 100644
--- a/tests/qtest/arm-cpu-features.c
+++ b/tests/qtest/arm-cpu-features.c
@@ -452,6 +452,7 @@ static void test_query_cpu_model_expansion(const void *data)
     assert_set_feature(qts, "max", "pmu", true);
 
     assert_has_not_feature(qts, "max", "kvm-no-adjvtime");
+    assert_has_not_feature(qts, "max", "kvm-steal-time");
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
         assert_has_feature_enabled(qts, "max", "aarch64");
@@ -493,6 +494,7 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
     assert_set_feature(qts, "host", "kvm-no-adjvtime", false);
 
     if (g_str_equal(qtest_get_arch(), "aarch64")) {
+        bool kvm_supports_steal_time;
         bool kvm_supports_sve;
         char max_name[8], name[8];
         uint32_t max_vq, vq;
@@ -500,6 +502,10 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         QDict *resp;
         char *error;
 
+        assert_error(qts, "cortex-a15",
+            "We cannot guarantee the CPU type 'cortex-a15' works "
+            "with KVM on this host", NULL);
+
         assert_has_feature_enabled(qts, "host", "aarch64");
 
         /* Enabling and disabling pmu should always work. */
@@ -507,16 +513,26 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         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 "
-            "with KVM on this host", NULL);
-
+        /*
+         * Some features would be enabled by default, but they're disabled
+         * because this instance of KVM doesn't support them. Test that the
+         * features are present, and, when enabled, issue further tests.
+         */
+        assert_has_feature(qts, "host", "kvm-steal-time");
         assert_has_feature(qts, "host", "sve");
+
         resp = do_query_no_props(qts, "host");
+        kvm_supports_steal_time = resp_get_feature(resp, "kvm-steal-time");
         kvm_supports_sve = resp_get_feature(resp, "sve");
         vls = resp_get_sve_vls(resp);
         qobject_unref(resp);
 
+        if (kvm_supports_steal_time) {
+            /* If we have steal-time then we should be able to toggle it. */
+            assert_set_feature(qts, "host", "kvm-steal-time", false);
+            assert_set_feature(qts, "host", "kvm-steal-time", true);
+        }
+
         if (kvm_supports_sve) {
             g_assert(vls != 0);
             max_vq = 64 - __builtin_clzll(vls);
@@ -577,6 +593,7 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         assert_has_not_feature(qts, "host", "aarch64");
         assert_has_not_feature(qts, "host", "pmu");
         assert_has_not_feature(qts, "host", "sve");
+        assert_has_not_feature(qts, "host", "kvm-steal-time");
     }
 
     qtest_quit(qts);
-- 
2.26.2

Re: [PATCH v4 6/6] hw/arm/virt: Implement kvm-steal-time

[Peter Maydell]

On Thu, 1 Oct 2020 at 07:17, Andrew Jones <drjones@redhat.com> wrote:
>
> We add the kvm-steal-time CPU property and implement it for machvirt.
> A tiny bit of refactoring was also done to allow pmu and pvtime to
> use the same vcpu device helper functions.

> +            if (pvtime_size > pvtime_reg_size) {
> +                error_report("pvtime requires a %ld byte memory region for "
> +                             "%d CPUs, but only %ld has been reserved",
> +                             pvtime_size, max_cpus, pvtime_reg_size);
> +                exit(1);
> +            }

This turns out not to compile on Windows:

../../hw/arm/virt.c:1693:30: error: format '%ld' expects argument of
type 'long int', but argument 2 has type 'hwaddr {aka long long
unsigned int}' [-Werror=format=]
                 error_report("pvtime requires a %ld byte memory region for "
                              ^

I'm going to squash this fix into the pullreq:

--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1690,8 +1690,9 @@ static void virt_cpu_post_init(VirtMachineState
*vms, int max_cpus,
             pvtime_size = REAL_HOST_PAGE_ALIGN(pvtime_size);

             if (pvtime_size > pvtime_reg_size) {
-                error_report("pvtime requires a %ld byte memory region for "
-                             "%d CPUs, but only %ld has been reserved",
+                error_report("pvtime requires a %" HWADDR_PRId
+                             " byte memory region for %d CPUs,"
+                             " but only %" HWADDR_PRId " has been reserved",
                              pvtime_size, max_cpus, pvtime_reg_size);
                 exit(1);
             }

thanks
-- PMM

Re: [PATCH v4 6/6] hw/arm/virt: Implement kvm-steal-time

[Andrew Jones]

Hi Peter,

Thanks for fixing this up and applying!

drew

On Thu, Oct 08, 2020 at 09:39:59PM +0100, Peter Maydell wrote:
> On Thu, 1 Oct 2020 at 07:17, Andrew Jones <drjones@redhat.com> wrote:
> >
> > We add the kvm-steal-time CPU property and implement it for machvirt.
> > A tiny bit of refactoring was also done to allow pmu and pvtime to
> > use the same vcpu device helper functions.
> 
> > +            if (pvtime_size > pvtime_reg_size) {
> > +                error_report("pvtime requires a %ld byte memory region for "
> > +                             "%d CPUs, but only %ld has been reserved",
> > +                             pvtime_size, max_cpus, pvtime_reg_size);
> > +                exit(1);
> > +            }
> 
> This turns out not to compile on Windows:
> 
> ../../hw/arm/virt.c:1693:30: error: format '%ld' expects argument of
> type 'long int', but argument 2 has type 'hwaddr {aka long long
> unsigned int}' [-Werror=format=]
>                  error_report("pvtime requires a %ld byte memory region for "
>                               ^
> 
> I'm going to squash this fix into the pullreq:
> 
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1690,8 +1690,9 @@ static void virt_cpu_post_init(VirtMachineState
> *vms, int max_cpus,
>              pvtime_size = REAL_HOST_PAGE_ALIGN(pvtime_size);
> 
>              if (pvtime_size > pvtime_reg_size) {
> -                error_report("pvtime requires a %ld byte memory region for "
> -                             "%d CPUs, but only %ld has been reserved",
> +                error_report("pvtime requires a %" HWADDR_PRId
> +                             " byte memory region for %d CPUs,"
> +                             " but only %" HWADDR_PRId " has been reserved",
>                               pvtime_size, max_cpus, pvtime_reg_size);
>                  exit(1);
>              }
> 
> thanks
> -- PMM
>

Re: [PATCH v4 0/6] hw/arm/virt: Introduce kvm-steal-time

[Peter Maydell]

On Thu, 1 Oct 2020 at 07:17, Andrew Jones <drjones@redhat.com> wrote:
>
> v4:
>   - Rebased to latest master
>   - Added an official linux header synch patch, replacing the
>     hack patch used in v3
>   - Added a patch to restore the arm-cpu-features test for AArch64
>     that got lost in the meson shuffle
>   - Added Eric's R-b's
>
> v3:
>   - Rebased: 5.2 machine type and kvm32 drop now included
>   - Switched to using new KVM cap that has been merged upstream
>   - Picked up some r-b's and some of Eric's comments from v2
>
> v2: https://www.mail-archive.com/qemu-devel@nongnu.org/msg727588.html



Applied to target-arm.next, thanks.

-- PMM