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  3. [PATCH v18 00/13] HVF: Add support for platform vGIC and nested virtualisation
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[PATCH v18 05/13] hw/arm, target/arm: nested virtualisation on HVF

Mohamed Mediouni posted 13 patches 1 month ago
Maintainers: Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Phil Dennis-Jordan <phil@philjordan.eu>, Peter Maydell <peter.maydell@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Alexander Graf <agraf@csgraf.de>
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[PATCH v18 05/13] hw/arm, target/arm: nested virtualisation on HVF
Posted by Mohamed Mediouni 1 month ago 
Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
---
 accel/hvf/hvf-all.c    |  1 +
 accel/stubs/hvf-stub.c |  1 +
 hw/arm/virt.c          |  5 +++++
 include/system/hvf.h   |  5 +++++
 target/arm/hvf/hvf.c   | 42 ++++++++++++++++++++++++++++++++++++++++--
 5 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/accel/hvf/hvf-all.c b/accel/hvf/hvf-all.c
index a296b108bc..1c1437b467 100644
--- a/accel/hvf/hvf-all.c
+++ b/accel/hvf/hvf-all.c
@@ -24,6 +24,7 @@
 
 bool hvf_allowed;
 bool hvf_kernel_irqchip;
+bool hvf_nested_virt;
 
 const char *hvf_return_string(hv_return_t ret)
 {
diff --git a/accel/stubs/hvf-stub.c b/accel/stubs/hvf-stub.c
index 6bd08759ba..cec1cbb056 100644
--- a/accel/stubs/hvf-stub.c
+++ b/accel/stubs/hvf-stub.c
@@ -11,3 +11,4 @@
 
 bool hvf_allowed;
 bool hvf_kernel_irqchip;
+bool hvf_nested_virt;
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 7a6fad1094..90769936d0 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2661,6 +2661,11 @@ static void virt_set_virt(Object *obj, bool value, Error **errp)
     VirtMachineState *vms = VIRT_MACHINE(obj);
 
     vms->virt = value;
+    /*
+     * At this point, HVF is not initialised yet.
+     * However, it needs to know if nested virt is enabled at init time.
+     */
+    hvf_nested_virt_enable(value);
 }
 
 static bool virt_get_highmem(Object *obj, Error **errp)
diff --git a/include/system/hvf.h b/include/system/hvf.h
index dc8da85979..0f0632f7ae 100644
--- a/include/system/hvf.h
+++ b/include/system/hvf.h
@@ -28,9 +28,14 @@ extern bool hvf_allowed;
 #define hvf_enabled() (hvf_allowed)
 extern bool hvf_kernel_irqchip;
 #define hvf_irqchip_in_kernel()  (hvf_kernel_irqchip)
+extern bool hvf_nested_virt;
+#define hvf_nested_virt_enabled()  (hvf_nested_virt)
+#define hvf_nested_virt_enable(enable) hvf_nested_virt = enable
 #else /* !CONFIG_HVF_IS_POSSIBLE */
 #define hvf_enabled() 0
 #define hvf_irqchip_in_kernel() 0
+#define hvf_nested_virt_enabled() 0
+#define hvf_nested_virt_enable(enable) 0
 #endif /* !CONFIG_HVF_IS_POSSIBLE */
 
 #define TYPE_HVF_ACCEL ACCEL_CLASS_NAME("hvf")
diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index d431d96ba3..d6ef4488fa 100644
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -27,6 +27,7 @@
 #include "system/memory.h"
 #include "hw/core/boards.h"
 #include "hw/core/irq.h"
+#include "hw/arm/virt.h"
 #include "qemu/main-loop.h"
 #include "system/cpus.h"
 #include "arm-powerctl.h"
@@ -1103,6 +1104,10 @@ static bool hvf_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
                      (1ULL << ARM_FEATURE_PMU) |
                      (1ULL << ARM_FEATURE_GENERIC_TIMER);
 
+    if (hvf_nested_virt_enabled()) {
+        ahcf->features |= 1ULL << ARM_FEATURE_EL2;
+    }
+
     for (i = 0; i < ARRAY_SIZE(regs); i++) {
         r |= hv_vcpu_config_get_feature_reg(config, regs[i].reg,
                                             &host_isar.idregs[regs[i].index]);
@@ -1218,6 +1223,19 @@ void hvf_arch_vcpu_destroy(CPUState *cpu)
     assert_hvf_ok(ret);
 }
 
+static bool hvf_arm_el2_supported(void)
+{
+    bool is_nested_virt_supported;
+    if (__builtin_available(macOS 15.0, *)) {
+        hv_return_t ret = hv_vm_config_get_el2_supported(&is_nested_virt_supported);
+        assert_hvf_ok(ret);
+    } else {
+        return false;
+    }
+    return is_nested_virt_supported;
+}
+
+
 hv_return_t hvf_arch_vm_create(MachineState *ms, uint32_t pa_range)
 {
     hv_return_t ret;
@@ -1229,6 +1247,20 @@ hv_return_t hvf_arch_vm_create(MachineState *ms, uint32_t pa_range)
     }
     chosen_ipa_bit_size = pa_range;
 
+    if (__builtin_available(macOS 15.0, *)) {
+        if (hvf_nested_virt_enabled()) {
+            if (!hvf_arm_el2_supported()) {
+                error_report("Nested virtualization not supported on this system.");
+                goto cleanup;
+            }
+            ret = hv_vm_config_set_el2_enabled(config, true);
+            if (ret != HV_SUCCESS) {
+                error_report("Failed to enable nested virtualization.");
+                goto cleanup;
+            }
+        }
+    }
+
     ret = hv_vm_create(config);
     if (hvf_irqchip_in_kernel()) {
         if (__builtin_available(macOS 15.0, *)) {
@@ -1420,6 +1452,13 @@ static void hvf_psci_cpu_off(ARMCPU *arm_cpu)
     assert(ret == QEMU_ARM_POWERCTL_RET_SUCCESS);
 }
 
+static int hvf_psci_get_target_el(void)
+{
+    if (hvf_nested_virt_enabled()) {
+        return 2;
+    }
+    return 1;
+}
 /*
  * Handle a PSCI call.
  *
@@ -1441,7 +1480,6 @@ static bool hvf_handle_psci_call(CPUState *cpu, int *excp_ret)
     CPUState *target_cpu_state;
     ARMCPU *target_cpu;
     target_ulong entry;
-    int target_el = 1;
     int32_t ret = 0;
 
     trace_arm_psci_call(param[0], param[1], param[2], param[3],
@@ -1495,7 +1533,7 @@ static bool hvf_handle_psci_call(CPUState *cpu, int *excp_ret)
         entry = param[2];
         context_id = param[3];
         ret = arm_set_cpu_on(mpidr, entry, context_id,
-                             target_el, target_aarch64);
+                             hvf_psci_get_target_el(), target_aarch64);
         break;
     case QEMU_PSCI_0_1_FN_CPU_OFF:
     case QEMU_PSCI_0_2_FN_CPU_OFF:
-- 
2.50.1 (Apple Git-155)
Re: [PATCH v18 05/13] hw/arm, target/arm: nested virtualisation on HVF
Posted by Philippe Mathieu-Daudé 1 month ago 
On 7/3/26 16:31, Mohamed Mediouni wrote:
> Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
> ---
>   accel/hvf/hvf-all.c    |  1 +
>   accel/stubs/hvf-stub.c |  1 +
>   hw/arm/virt.c          |  5 +++++
>   include/system/hvf.h   |  5 +++++
>   target/arm/hvf/hvf.c   | 42 ++++++++++++++++++++++++++++++++++++++++--
>   5 files changed, 52 insertions(+), 2 deletions(-)


> diff --git a/include/system/hvf.h b/include/system/hvf.h
> index dc8da85979..0f0632f7ae 100644
> --- a/include/system/hvf.h
> +++ b/include/system/hvf.h
> @@ -28,9 +28,14 @@ extern bool hvf_allowed;
>   #define hvf_enabled() (hvf_allowed)
>   extern bool hvf_kernel_irqchip;
>   #define hvf_irqchip_in_kernel()  (hvf_kernel_irqchip)
> +extern bool hvf_nested_virt;
> +#define hvf_nested_virt_enabled()  (hvf_nested_virt)
> +#define hvf_nested_virt_enable(enable) hvf_nested_virt = enable

Unsafe macro. Better expose the method and add a stub.

>   #else /* !CONFIG_HVF_IS_POSSIBLE */
>   #define hvf_enabled() 0
>   #define hvf_irqchip_in_kernel() 0
> +#define hvf_nested_virt_enabled() 0
> +#define hvf_nested_virt_enable(enable) 0
>   #endif /* !CONFIG_HVF_IS_POSSIBLE */
Re: [PATCH v18 05/13] hw/arm, target/arm: nested virtualisation on HVF
Posted by Mohamed Mediouni 1 month ago 

> On 7. Mar 2026, at 16:48, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
> 
> On 7/3/26 16:31, Mohamed Mediouni wrote:
>> Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
>> ---
>>  accel/hvf/hvf-all.c    |  1 +
>>  accel/stubs/hvf-stub.c |  1 +
>>  hw/arm/virt.c          |  5 +++++
>>  include/system/hvf.h   |  5 +++++
>>  target/arm/hvf/hvf.c   | 42 ++++++++++++++++++++++++++++++++++++++++--
>>  5 files changed, 52 insertions(+), 2 deletions(-)
> 
> 
>> diff --git a/include/system/hvf.h b/include/system/hvf.h
>> index dc8da85979..0f0632f7ae 100644
>> --- a/include/system/hvf.h
>> +++ b/include/system/hvf.h
>> @@ -28,9 +28,14 @@ extern bool hvf_allowed;
>>  #define hvf_enabled() (hvf_allowed)
>>  extern bool hvf_kernel_irqchip;
>>  #define hvf_irqchip_in_kernel()  (hvf_kernel_irqchip)
>> +extern bool hvf_nested_virt;
>> +#define hvf_nested_virt_enabled()  (hvf_nested_virt)
>> +#define hvf_nested_virt_enable(enable) hvf_nested_virt = enable
> 
> Unsafe macro. Better expose the method and add a stub.
> 
Does this look saner? If so can send a rev with it…

diff --git a/accel/hvf/hvf-all.c b/accel/hvf/hvf-all.c
index 1c1437b467..66c3b48608 100644
--- a/accel/hvf/hvf-all.c
+++ b/accel/hvf/hvf-all.c
@@ -26,6 +26,10 @@ bool hvf_allowed;
 bool hvf_kernel_irqchip;
 bool hvf_nested_virt;
 
+void hvf_nested_virt_enable(bool nested_virt) {
+    hvf_nested_virt = nested_virt;
+}
+
 const char *hvf_return_string(hv_return_t ret)
 {
     switch (ret) {
diff --git a/accel/stubs/hvf-stub.c b/accel/stubs/hvf-stub.c
index cec1cbb056..dc365c5307 100644
--- a/accel/stubs/hvf-stub.c
+++ b/accel/stubs/hvf-stub.c
@@ -12,3 +12,12 @@
 bool hvf_allowed;
 bool hvf_kernel_irqchip;
 bool hvf_nested_virt;
+
+void hvf_nested_virt_enable(bool nested_virt) {
+    /*
+     * This is called unconditionally from hw/arm/virt.c
+     * because we don't know if HVF is going to be used
+     * as that step of initialisation happens later.
+     * As such, do nothing here instead of marking as unreachable.
+     */
+}
diff --git a/include/system/hvf.h b/include/system/hvf.h
index 0f0632f7ae..a961df8b95 100644
--- a/include/system/hvf.h
+++ b/include/system/hvf.h
@@ -30,14 +30,14 @@ extern bool hvf_kernel_irqchip;
 #define hvf_irqchip_in_kernel()  (hvf_kernel_irqchip)
 extern bool hvf_nested_virt;
 #define hvf_nested_virt_enabled()  (hvf_nested_virt)
-#define hvf_nested_virt_enable(enable) hvf_nested_virt = enable
 #else /* !CONFIG_HVF_IS_POSSIBLE */
 #define hvf_enabled() 0
 #define hvf_irqchip_in_kernel() 0
 #define hvf_nested_virt_enabled() 0
-#define hvf_nested_virt_enable(enable) 0
 #endif /* !CONFIG_HVF_IS_POSSIBLE */
 
+void hvf_nested_virt_enable(bool nested_virt);
+
 #define TYPE_HVF_ACCEL ACCEL_CLASS_NAME("hvf")
 
 typedef struct HVFState HVFState;

>>  #else /* !CONFIG_HVF_IS_POSSIBLE */
>>  #define hvf_enabled() 0
>>  #define hvf_irqchip_in_kernel() 0
>> +#define hvf_nested_virt_enabled() 0
>> +#define hvf_nested_virt_enable(enable) 0
>>  #endif /* !CONFIG_HVF_IS_POSSIBLE */
> 
>
Re: [PATCH v18 05/13] hw/arm, target/arm: nested virtualisation on HVF
Posted by Philippe Mathieu-Daudé 1 month ago 
On 7/3/26 17:21, Mohamed Mediouni wrote:
> 
> 
>> On 7. Mar 2026, at 16:48, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>>
>> On 7/3/26 16:31, Mohamed Mediouni wrote:
>>> Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
>>> ---
>>>   accel/hvf/hvf-all.c    |  1 +
>>>   accel/stubs/hvf-stub.c |  1 +
>>>   hw/arm/virt.c          |  5 +++++
>>>   include/system/hvf.h   |  5 +++++
>>>   target/arm/hvf/hvf.c   | 42 ++++++++++++++++++++++++++++++++++++++++--
>>>   5 files changed, 52 insertions(+), 2 deletions(-)
>>
>>
>>> diff --git a/include/system/hvf.h b/include/system/hvf.h
>>> index dc8da85979..0f0632f7ae 100644
>>> --- a/include/system/hvf.h
>>> +++ b/include/system/hvf.h
>>> @@ -28,9 +28,14 @@ extern bool hvf_allowed;
>>>   #define hvf_enabled() (hvf_allowed)
>>>   extern bool hvf_kernel_irqchip;
>>>   #define hvf_irqchip_in_kernel()  (hvf_kernel_irqchip)
>>> +extern bool hvf_nested_virt;
>>> +#define hvf_nested_virt_enabled()  (hvf_nested_virt)
>>> +#define hvf_nested_virt_enable(enable) hvf_nested_virt = enable
>>
>> Unsafe macro. Better expose the method and add a stub.
>>
> Does this look saner? If so can send a rev with it…

LGTM!

> 
> diff --git a/accel/hvf/hvf-all.c b/accel/hvf/hvf-all.c
> index 1c1437b467..66c3b48608 100644
> --- a/accel/hvf/hvf-all.c
> +++ b/accel/hvf/hvf-all.c
> @@ -26,6 +26,10 @@ bool hvf_allowed;
>   bool hvf_kernel_irqchip;
>   bool hvf_nested_virt;
>   
> +void hvf_nested_virt_enable(bool nested_virt) {
> +    hvf_nested_virt = nested_virt;
> +}
> +
>   const char *hvf_return_string(hv_return_t ret)
>   {
>       switch (ret) {
> diff --git a/accel/stubs/hvf-stub.c b/accel/stubs/hvf-stub.c
> index cec1cbb056..dc365c5307 100644
> --- a/accel/stubs/hvf-stub.c
> +++ b/accel/stubs/hvf-stub.c
> @@ -12,3 +12,12 @@
>   bool hvf_allowed;
>   bool hvf_kernel_irqchip;
>   bool hvf_nested_virt;
> +
> +void hvf_nested_virt_enable(bool nested_virt) {
> +    /*
> +     * This is called unconditionally from hw/arm/virt.c
> +     * because we don't know if HVF is going to be used
> +     * as that step of initialisation happens later.
> +     * As such, do nothing here instead of marking as unreachable.
> +     */
> +}
> diff --git a/include/system/hvf.h b/include/system/hvf.h
> index 0f0632f7ae..a961df8b95 100644
> --- a/include/system/hvf.h
> +++ b/include/system/hvf.h
> @@ -30,14 +30,14 @@ extern bool hvf_kernel_irqchip;
>   #define hvf_irqchip_in_kernel()  (hvf_kernel_irqchip)
>   extern bool hvf_nested_virt;
>   #define hvf_nested_virt_enabled()  (hvf_nested_virt)
> -#define hvf_nested_virt_enable(enable) hvf_nested_virt = enable
>   #else /* !CONFIG_HVF_IS_POSSIBLE */
>   #define hvf_enabled() 0
>   #define hvf_irqchip_in_kernel() 0
>   #define hvf_nested_virt_enabled() 0
> -#define hvf_nested_virt_enable(enable) 0
>   #endif /* !CONFIG_HVF_IS_POSSIBLE */
>   
> +void hvf_nested_virt_enable(bool nested_virt);
> +
>   #define TYPE_HVF_ACCEL ACCEL_CLASS_NAME("hvf")
>   
>   typedef struct HVFState HVFState;
> 
>>>   #else /* !CONFIG_HVF_IS_POSSIBLE */
>>>   #define hvf_enabled() 0
>>>   #define hvf_irqchip_in_kernel() 0
>>> +#define hvf_nested_virt_enabled() 0
>>> +#define hvf_nested_virt_enable(enable) 0
>>>   #endif /* !CONFIG_HVF_IS_POSSIBLE */
>>
>>
>

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