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Re: [Qemu-arm] [Qemu-devel] [PATCH v5 07/18] kvm: add kvm_arm_get_max_vm


From: Jia He
Subject: Re: [Qemu-arm] [Qemu-devel] [PATCH v5 07/18] kvm: add kvm_arm_get_max_vm_phys_shift
Date: Tue, 29 Jan 2019 22:25:31 +0800
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0

Hi Eric

On 2019/1/23 18:14, Eric Auger wrote:
Add the kvm_arm_get_max_vm_phys_shift() helper that returns the
log of the maximum IPA size supported by KVM. This capability
needs to be known to create the VM with a specific IPA max size
(kvm_type passed along KVM_CREATE_VM ioctl.

Signed-off-by: Eric Auger <address@hidden>

---
v3 -> v4:
- s/s/ms in kvm_arm_get_max_vm_phys_shift function comment
- check KVM_CAP_ARM_VM_IPA_SIZE extension

v1 -> v2:
- put this in ARM specific code
---
  target/arm/kvm.c     |  8 ++++++++
  target/arm/kvm_arm.h | 16 ++++++++++++++++
  2 files changed, 24 insertions(+)

diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index e00ccf9c98..877c588ef5 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -18,6 +18,7 @@
  #include "qemu/error-report.h"
  #include "sysemu/sysemu.h"
  #include "sysemu/kvm.h"
+#include "sysemu/kvm_int.h"
  #include "kvm_arm.h"
  #include "cpu.h"
  #include "trace.h"
@@ -162,6 +163,13 @@ void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
      env->features = arm_host_cpu_features.features;
  }
+int kvm_arm_get_max_vm_phys_shift(MachineState *ms)
+{
+    KVMState *s = KVM_STATE(ms->accelerator);
+
+    return kvm_check_extension(s, KVM_CAP_ARM_VM_IPA_SIZE);

If KVM_CAP_ARM_VM_IPA_SIZE is not supported in host kernel, would it be

better if kvm_arm_get_max_vm_phys_shift returns a default value

(e.g. 40),instead of an errno?

---
Cheers,
Jia He

+}
+
  int kvm_arch_init(MachineState *ms, KVMState *s)
  {
      /* For ARM interrupt delivery is always asynchronous,
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index 6393455b1d..5969c41f83 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -207,6 +207,17 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures 
*ahcf);
   */
  void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu);
+/**
+ * kvm_arm_get_max_vm_phys_shift - Returns log2 of the max IPA size
+ * supported by KVM
+ *
+ * @ms: Machine state handle
+ *
+ * Return the max number of IPA bits or a negative value if
+ * the host kernel does not expose this value.
+ */
+int kvm_arm_get_max_vm_phys_shift(MachineState *ms);
+
  /**
   * kvm_arm_sync_mpstate_to_kvm
   * @cpu: ARMCPU
@@ -239,6 +250,11 @@ static inline void 
kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
      cpu->host_cpu_probe_failed = true;
  }
+static inline int kvm_arm_get_max_vm_phys_shift(MachineState *ms)
+{
+    return -ENOENT;
+}
+
  static inline int kvm_arm_vgic_probe(void)
  {
      return 0;




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