[PATCH v4 0/4] Target CPU=Host implementation for KVM ARM/ARM64

[PATCH v4 0/4] Target CPU=Host implementation for KVM ARM/ARM64

[Anup Patel]

It will be very useful for user space (QEMU/KVMTOOL) if it has a
method of querying VCPU target type matching to underlying Host.
We can use such querying mechanism and implement machine models
in user space where VCPU target type is always same-as/similar-to
underlying Host (i.e. Target CPU=Host).

This patch series implements KVM_ARM_PREFERRED_TARGET vm ioclt for
querying VCPU target type matching underlying host. Using this new
ioctl we can implement VCPU target CPU=Host in user space.

Also, it is not mandatory to call KVM_ARM_PREFERRED_TARGET vm ioctl
and the old method of trying all possible target types using the
KVM_ARM_VCPU_INIT ioctl to initialize VCPU works fine.

V4:
 - Fixed files exchanged between patches
 - For now return zeroed features in struct kvm_vcpu_init instance

V3:
 - Return -ENODEV if no preferred target available for host
 - Make KVM_ARM_PREFERRED_TARGET ioctl as vm ioctl

V2:
 - Renamed the ioclt to KVM_ARM_PREFERRED_TARGET
 - Return struct kvm_vcpu_init instace instead of just target type

V1:
 - Initial patch-set with ioctl named as KVM_ARM_SUITABLE_TARGET

Anup Patel (4):
  ARM: KVM: Implement kvm_vcpu_preferred_target() function
  ARM64: KVM: Implement kvm_vcpu_preferred_target() function
  ARM/ARM64: KVM: Implement KVM_ARM_PREFERRED_TARGET ioctl
  KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

 Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
 arch/arm/include/asm/kvm_host.h   |    1 +
 arch/arm/kvm/arm.c                |   13 +++++++++++++
 arch/arm/kvm/guest.c              |   20 ++++++++++++++++++++
 arch/arm64/include/asm/kvm_host.h |    1 +
 arch/arm64/kvm/guest.c            |   20 ++++++++++++++++++++
 include/uapi/linux/kvm.h          |    1 +
 7 files changed, 79 insertions(+), 4 deletions(-)

-- 
1.7.9.5

[PATCH v4 1/4] ARM: KVM: Implement kvm_vcpu_preferred_target() function

[Anup Patel]

This patch implements kvm_vcpu_preferred_target() function for
KVM ARM which will help us implement KVM_ARM_PREFERRED_TARGET ioctl
for user space.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
---
 arch/arm/include/asm/kvm_host.h |    1 +
 arch/arm/kvm/guest.c            |   20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 7d22517..76f3c19 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -154,6 +154,7 @@ struct kvm_vcpu_stat {
 struct kvm_vcpu_init;
 int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 			const struct kvm_vcpu_init *init);
+int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init);
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
 int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
 struct kvm_one_reg;
diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index 152d036..21beea0 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -222,6 +222,26 @@ int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 	return kvm_reset_vcpu(vcpu);
 }
 
+int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init)
+{
+	int target = kvm_target_cpu();
+
+	if (target < 0)
+		return -ENODEV;
+
+	memset(init, 0, sizeof(*init));
+
+	/* 
+	 * For now, we don't return any features.
+	 * In future, we might use features to return target
+	 * specific features available for the preferred
+	 * target type.
+	 */
+	init->target = (__u32)target;
+
+	return 0;
+}
+
 int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
 {
 	return -EINVAL;
-- 
1.7.9.5

[PATCH v4 2/4] ARM64: KVM: Implement kvm_vcpu_preferred_target() function

[Anup Patel]

This patch implements kvm_vcpu_preferred_target() function for
KVM ARM64 which will help us implement KVM_ARM_PREFERRED_TARGET
ioctl for user space.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
---
 arch/arm64/include/asm/kvm_host.h |    1 +
 arch/arm64/kvm/guest.c            |   20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f318c43..b609db3 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -156,6 +156,7 @@ struct kvm_vcpu_stat {
 struct kvm_vcpu_init;
 int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 			const struct kvm_vcpu_init *init);
+int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init);
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
 int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
 struct kvm_one_reg;
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index d7bf7d6..94e4b7a 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -254,6 +254,26 @@ int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
 	return kvm_reset_vcpu(vcpu);
 }
 
+int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init)
+{
+	int target = kvm_target_cpu();
+
+	if (target < 0)
+		return -ENODEV;
+
+	memset(init, 0, sizeof(*init));
+
+	/* 
+	 * For now, we don't return any features.
+	 * In future, we might use features to return target
+	 * specific features available for the preferred
+	 * target type.
+	 */
+	init->target = (__u32)target;
+
+	return 0;
+}
+
 int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
 {
 	return -EINVAL;
-- 
1.7.9.5

[PATCH v4 3/4] ARM/ARM64: KVM: Implement KVM_ARM_PREFERRED_TARGET ioctl

[Anup Patel]

For implementing CPU=host, we need a mechanism for querying
preferred VCPU target type on underlying Host.

This patch implements KVM_ARM_PREFERRED_TARGET vm ioctl which
returns struct kvm_vcpu_init instance containing information
about preferred VCPU target type and target specific features
available for it.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
---
 arch/arm/kvm/arm.c       |   13 +++++++++++++
 include/uapi/linux/kvm.h |    1 +
 2 files changed, 14 insertions(+)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 9c697db..cc5adb9 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -797,6 +797,19 @@ long kvm_arch_vm_ioctl(struct file *filp,
 			return -EFAULT;
 		return kvm_vm_ioctl_set_device_addr(kvm, &dev_addr);
 	}
+	case KVM_ARM_PREFERRED_TARGET: {
+		int err;
+		struct kvm_vcpu_init init;
+
+		err = kvm_vcpu_preferred_target(&init);
+		if (err)
+			return err;
+
+		if (copy_to_user(argp, &init, sizeof(init)))
+			return -EFAULT;
+
+		return 0;
+	}
 	default:
 		return -EINVAL;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 99c2533..e32e776 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1012,6 +1012,7 @@ struct kvm_s390_ucas_mapping {
 /* VM is being stopped by host */
 #define KVM_KVMCLOCK_CTRL	  _IO(KVMIO,   0xad)
 #define KVM_ARM_VCPU_INIT	  _IOW(KVMIO,  0xae, struct kvm_vcpu_init)
+#define KVM_ARM_PREFERRED_TARGET  _IOR(KVMIO,  0xaf, struct kvm_vcpu_init)
 #define KVM_GET_REG_LIST	  _IOWR(KVMIO, 0xb0, struct kvm_reg_list)
 
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1 << 0)
-- 
1.7.9.5

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Anup Patel]

To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
vm ioctl which provides information to user space required for
creating VCPU matching underlying Host.

This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
vm ioctl in the KVM API documentation.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
---
 Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 858aecf..f31e6e8 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2303,8 +2303,28 @@ Possible features:
 	- KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
 	  Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
 
+4.83 KVM_ARM_PREFERRED_TARGET
 
-4.83 KVM_GET_REG_LIST
+Capability: basic
+Architectures: arm, arm64
+Type: vm ioctl
+Parameters: struct struct kvm_vcpu_init (out)
+Returns: 0 on success; -1 on error
+Errors:
+ ?ENODEV: ???no preferred target available for the host
+
+This queries KVM for preferred CPU target type which can be emulated
+by KVM on underlying host.
+
+The ioctl returns struct kvm_vcpu_init instance containing information
+about preferred CPU target type and target specific features available
+for it.
+
+The information returned by this ioctl can be used to prepare instance
+of struct kvm_vcpu_init for KVM_ARM_VCPU_INIT ioctl which will result
+in VCPU matching underlying host.
+
+4.84 KVM_GET_REG_LIST
 
 Capability: basic
 Architectures: arm, arm64
@@ -2323,8 +2343,7 @@ struct kvm_reg_list {
 This ioctl returns the guest registers that are supported for the
 KVM_GET_ONE_REG/KVM_SET_ONE_REG calls.
 
-
-4.84 KVM_ARM_SET_DEVICE_ADDR
+4.85 KVM_ARM_SET_DEVICE_ADDR
 
 Capability: KVM_CAP_ARM_SET_DEVICE_ADDR
 Architectures: arm, arm64
@@ -2362,7 +2381,7 @@ must be called after calling KVM_CREATE_IRQCHIP, but before calling
 KVM_RUN on any of the VCPUs.  Calling this ioctl twice for any of the
 base addresses will return -EEXIST.
 
-4.85 KVM_PPC_RTAS_DEFINE_TOKEN
+4.86 KVM_PPC_RTAS_DEFINE_TOKEN
 
 Capability: KVM_CAP_PPC_RTAS
 Architectures: ppc
-- 
1.7.9.5

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Alexander Graf]

On 25.09.2013, at 11:26, Anup Patel wrote:

> To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
> vm ioctl which provides information to user space required for
> creating VCPU matching underlying Host.
> 
> This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
> vm ioctl in the KVM API documentation.
> 
> Signed-off-by: Anup Patel <anup.patel@linaro.org>
> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
> ---
> Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
> 1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 858aecf..f31e6e8 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2303,8 +2303,28 @@ Possible features:
> 	- KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
> 	  Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
> 
> +4.83 KVM_ARM_PREFERRED_TARGET

Why 4.83 and not 4.86? It feels backwards to rename all these other sections.


Alex

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Anup Patel]

On Wed, Sep 25, 2013 at 5:43 PM, Alexander Graf <agraf@suse.de> wrote:
>
> On 25.09.2013, at 11:26, Anup Patel wrote:
>
>> To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
>> vm ioctl which provides information to user space required for
>> creating VCPU matching underlying Host.
>>
>> This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
>> vm ioctl in the KVM API documentation.
>>
>> Signed-off-by: Anup Patel <anup.patel@linaro.org>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
>> ---
>> Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
>> 1 file changed, 23 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index 858aecf..f31e6e8 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -2303,8 +2303,28 @@ Possible features:
>>       - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
>>         Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
>>
>> +4.83 KVM_ARM_PREFERRED_TARGET
>
> Why 4.83 and not 4.86? It feels backwards to rename all these other sections.

I wanted to have KVM_ARM_xxxx IOCTLs located nearby hence
placed KVM_ARM_PREFERRED_TARGET after KVM_ARM_VCPU_INIT.

There is no point in keeping KVM_ARM_PREFERRED_TARGET
after KVM_PPC_RTAS_DEFINE_TOKEN and make
KVM_PPC_RTAS_DEFINE_TOKEN dangle in-between documentation
of various KVM_ARM_xxxx IOCTLs.

>
>
> Alex
>
>
> _______________________________________________
> kvmarm mailing list
> kvmarm at lists.cs.columbia.edu
> https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm

--Anup

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Christoffer Dall]

On Wed, Sep 25, 2013 at 05:58:07PM +0530, Anup Patel wrote:
> On Wed, Sep 25, 2013 at 5:43 PM, Alexander Graf <agraf@suse.de> wrote:
> >
> > On 25.09.2013, at 11:26, Anup Patel wrote:
> >
> >> To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
> >> vm ioctl which provides information to user space required for
> >> creating VCPU matching underlying Host.
> >>
> >> This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
> >> vm ioctl in the KVM API documentation.
> >>
> >> Signed-off-by: Anup Patel <anup.patel@linaro.org>
> >> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
> >> ---
> >> Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
> >> 1 file changed, 23 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> >> index 858aecf..f31e6e8 100644
> >> --- a/Documentation/virtual/kvm/api.txt
> >> +++ b/Documentation/virtual/kvm/api.txt
> >> @@ -2303,8 +2303,28 @@ Possible features:
> >>       - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
> >>         Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
> >>
> >> +4.83 KVM_ARM_PREFERRED_TARGET
> >
> > Why 4.83 and not 4.86? It feels backwards to rename all these other sections.
> 
> I wanted to have KVM_ARM_xxxx IOCTLs located nearby hence
> placed KVM_ARM_PREFERRED_TARGET after KVM_ARM_VCPU_INIT.
> 
> There is no point in keeping KVM_ARM_PREFERRED_TARGET
> after KVM_PPC_RTAS_DEFINE_TOKEN and make
> KVM_PPC_RTAS_DEFINE_TOKEN dangle in-between documentation
> of various KVM_ARM_xxxx IOCTLs.
> 
I checked the git log and this is not the first time this has happened,
so I think Anup's point here is valid.

-Christoffer

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Christoffer Dall]

On Wed, Sep 25, 2013 at 02:56:03PM +0530, Anup Patel wrote:
> To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
> vm ioctl which provides information to user space required for
> creating VCPU matching underlying Host.
> 
> This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
> vm ioctl in the KVM API documentation.
> 
> Signed-off-by: Anup Patel <anup.patel@linaro.org>
> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
> ---
>  Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
>  1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 858aecf..f31e6e8 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2303,8 +2303,28 @@ Possible features:
>  	- KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
>  	  Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
>  
> +4.83 KVM_ARM_PREFERRED_TARGET
>  
> -4.83 KVM_GET_REG_LIST

I think the convention here is to keep two new lines after a Section.

> +Capability: basic
> +Architectures: arm, arm64
> +Type: vm ioctl
> +Parameters: struct struct kvm_vcpu_init (out)
> +Returns: 0 on success; -1 on error
> +Errors:
> + ?ENODEV: ???no preferred target available for the host
> +
> +This queries KVM for preferred CPU target type which can be emulated
> +by KVM on underlying host.
> +
> +The ioctl returns struct kvm_vcpu_init instance containing information
> +about preferred CPU target type and target specific features available
> +for it.
> +
> +The information returned by this ioctl can be used to prepare instance

an instance

> +of struct kvm_vcpu_init for KVM_ARM_VCPU_INIT ioctl which will result

the KVM_ARM_VCPU_INIT ioctl.
(the last part is not necessarily true is it?  It's only a best bet,
think for example about Big.Little...)

> +in VCPU matching underlying host.

You also need to add something about the features here:

The kvm_vcpu_init->features bitmap will have feature bits set if the
preferred target recommends setting these features, but this is not
required.

> +
> +4.84 KVM_GET_REG_LIST
>  
>  Capability: basic
>  Architectures: arm, arm64
> @@ -2323,8 +2343,7 @@ struct kvm_reg_list {
>  This ioctl returns the guest registers that are supported for the
>  KVM_GET_ONE_REG/KVM_SET_ONE_REG calls.
>  
> -
> -4.84 KVM_ARM_SET_DEVICE_ADDR
> +4.85 KVM_ARM_SET_DEVICE_ADDR
>  
>  Capability: KVM_CAP_ARM_SET_DEVICE_ADDR
>  Architectures: arm, arm64
> @@ -2362,7 +2381,7 @@ must be called after calling KVM_CREATE_IRQCHIP, but before calling
>  KVM_RUN on any of the VCPUs.  Calling this ioctl twice for any of the
>  base addresses will return -EEXIST.
>  
> -4.85 KVM_PPC_RTAS_DEFINE_TOKEN
> +4.86 KVM_PPC_RTAS_DEFINE_TOKEN
>  
>  Capability: KVM_CAP_PPC_RTAS
>  Architectures: ppc
> -- 
> 1.7.9.5
> 

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Alexander Graf]

On 25.09.2013, at 18:19, Christoffer Dall wrote:

> On Wed, Sep 25, 2013 at 05:58:07PM +0530, Anup Patel wrote:
>> On Wed, Sep 25, 2013 at 5:43 PM, Alexander Graf <agraf@suse.de> wrote:
>>> 
>>> On 25.09.2013, at 11:26, Anup Patel wrote:
>>> 
>>>> To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
>>>> vm ioctl which provides information to user space required for
>>>> creating VCPU matching underlying Host.
>>>> 
>>>> This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
>>>> vm ioctl in the KVM API documentation.
>>>> 
>>>> Signed-off-by: Anup Patel <anup.patel@linaro.org>
>>>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
>>>> ---
>>>> Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
>>>> 1 file changed, 23 insertions(+), 4 deletions(-)
>>>> 
>>>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>>>> index 858aecf..f31e6e8 100644
>>>> --- a/Documentation/virtual/kvm/api.txt
>>>> +++ b/Documentation/virtual/kvm/api.txt
>>>> @@ -2303,8 +2303,28 @@ Possible features:
>>>>      - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
>>>>        Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
>>>> 
>>>> +4.83 KVM_ARM_PREFERRED_TARGET
>>> 
>>> Why 4.83 and not 4.86? It feels backwards to rename all these other sections.
>> 
>> I wanted to have KVM_ARM_xxxx IOCTLs located nearby hence
>> placed KVM_ARM_PREFERRED_TARGET after KVM_ARM_VCPU_INIT.
>> 
>> There is no point in keeping KVM_ARM_PREFERRED_TARGET
>> after KVM_PPC_RTAS_DEFINE_TOKEN and make
>> KVM_PPC_RTAS_DEFINE_TOKEN dangle in-between documentation
>> of various KVM_ARM_xxxx IOCTLs.
>> 
> I checked the git log and this is not the first time this has happened,
> so I think Anup's point here is valid.

Well, I think it makes sense to be consistent here. Maybe we should add a new section for arch specific ioctls so that we get our own number space? But regardless, all subarchs should try and follow the same scheme - regardless of what the scheme is :).


Alex

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Anup Patel]

On Thu, Sep 26, 2013 at 1:40 AM, Christoffer Dall
<christoffer.dall@linaro.org> wrote:
> On Wed, Sep 25, 2013 at 02:56:03PM +0530, Anup Patel wrote:
>> To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
>> vm ioctl which provides information to user space required for
>> creating VCPU matching underlying Host.
>>
>> This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
>> vm ioctl in the KVM API documentation.
>>
>> Signed-off-by: Anup Patel <anup.patel@linaro.org>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
>> ---
>>  Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
>>  1 file changed, 23 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index 858aecf..f31e6e8 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -2303,8 +2303,28 @@ Possible features:
>>       - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
>>         Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
>>
>> +4.83 KVM_ARM_PREFERRED_TARGET
>>
>> -4.83 KVM_GET_REG_LIST
>
> I think the convention here is to keep two new lines after a Section.

Well this is not be consistenly followed by everyone.
Please look at the api.txt again.

Anyways, I will change and keep two new lines after a Section.

>
>> +Capability: basic
>> +Architectures: arm, arm64
>> +Type: vm ioctl
>> +Parameters: struct struct kvm_vcpu_init (out)
>> +Returns: 0 on success; -1 on error
>> +Errors:
>> +  ENODEV:    no preferred target available for the host
>> +
>> +This queries KVM for preferred CPU target type which can be emulated
>> +by KVM on underlying host.
>> +
>> +The ioctl returns struct kvm_vcpu_init instance containing information
>> +about preferred CPU target type and target specific features available
>> +for it.
>> +
>> +The information returned by this ioctl can be used to prepare instance
>
> an instance

Ok.

>
>> +of struct kvm_vcpu_init for KVM_ARM_VCPU_INIT ioctl which will result
>
> the KVM_ARM_VCPU_INIT ioctl.
> (the last part is not necessarily true is it?  It's only a best bet,
> think for example about Big.Little...)
>
>> +in VCPU matching underlying host.
>
> You also need to add something about the features here:
>
> The kvm_vcpu_init->features bitmap will have feature bits set if the
> preferred target recommends setting these features, but this is not
> required.

Ok.

>
>> +
>> +4.84 KVM_GET_REG_LIST
>>
>>  Capability: basic
>>  Architectures: arm, arm64
>> @@ -2323,8 +2343,7 @@ struct kvm_reg_list {
>>  This ioctl returns the guest registers that are supported for the
>>  KVM_GET_ONE_REG/KVM_SET_ONE_REG calls.
>>
>> -
>> -4.84 KVM_ARM_SET_DEVICE_ADDR
>> +4.85 KVM_ARM_SET_DEVICE_ADDR
>>
>>  Capability: KVM_CAP_ARM_SET_DEVICE_ADDR
>>  Architectures: arm, arm64
>> @@ -2362,7 +2381,7 @@ must be called after calling KVM_CREATE_IRQCHIP, but before calling
>>  KVM_RUN on any of the VCPUs.  Calling this ioctl twice for any of the
>>  base addresses will return -EEXIST.
>>
>> -4.85 KVM_PPC_RTAS_DEFINE_TOKEN
>> +4.86 KVM_PPC_RTAS_DEFINE_TOKEN
>>
>>  Capability: KVM_CAP_PPC_RTAS
>>  Architectures: ppc
>> --
>> 1.7.9.5
>>
> _______________________________________________
> kvmarm mailing list
> kvmarm at lists.cs.columbia.edu
> https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm

--Anup

[PATCH v4 4/4] KVM: Add documentation for KVM_ARM_PREFERRED_TARGET ioctl

[Alexander Graf]

On 26.09.2013, at 00:26, Alexander Graf wrote:

> 
> On 25.09.2013, at 18:19, Christoffer Dall wrote:
> 
>> On Wed, Sep 25, 2013 at 05:58:07PM +0530, Anup Patel wrote:
>>> On Wed, Sep 25, 2013 at 5:43 PM, Alexander Graf <agraf@suse.de> wrote:
>>>> 
>>>> On 25.09.2013, at 11:26, Anup Patel wrote:
>>>> 
>>>>> To implement CPU=Host we have added KVM_ARM_PREFERRED_TARGET
>>>>> vm ioctl which provides information to user space required for
>>>>> creating VCPU matching underlying Host.
>>>>> 
>>>>> This patch adds info related to this new KVM_ARM_PREFERRED_TARGET
>>>>> vm ioctl in the KVM API documentation.
>>>>> 
>>>>> Signed-off-by: Anup Patel <anup.patel@linaro.org>
>>>>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
>>>>> ---
>>>>> Documentation/virtual/kvm/api.txt |   27 +++++++++++++++++++++++----
>>>>> 1 file changed, 23 insertions(+), 4 deletions(-)
>>>>> 
>>>>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>>>>> index 858aecf..f31e6e8 100644
>>>>> --- a/Documentation/virtual/kvm/api.txt
>>>>> +++ b/Documentation/virtual/kvm/api.txt
>>>>> @@ -2303,8 +2303,28 @@ Possible features:
>>>>>     - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
>>>>>       Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
>>>>> 
>>>>> +4.83 KVM_ARM_PREFERRED_TARGET
>>>> 
>>>> Why 4.83 and not 4.86? It feels backwards to rename all these other sections.
>>> 
>>> I wanted to have KVM_ARM_xxxx IOCTLs located nearby hence
>>> placed KVM_ARM_PREFERRED_TARGET after KVM_ARM_VCPU_INIT.
>>> 
>>> There is no point in keeping KVM_ARM_PREFERRED_TARGET
>>> after KVM_PPC_RTAS_DEFINE_TOKEN and make
>>> KVM_PPC_RTAS_DEFINE_TOKEN dangle in-between documentation
>>> of various KVM_ARM_xxxx IOCTLs.
>>> 
>> I checked the git log and this is not the first time this has happened,
>> so I think Anup's point here is valid.
> 
> Well, I think it makes sense to be consistent here. Maybe we should add a new section for arch specific ioctls so that we get our own number space? But regardless, all subarchs should try and follow the same scheme - regardless of what the scheme is :).

Ok, I think I finally grasped what Anup was trying to say. The ioctl id for this one is 0xaf, in between 0xae (KVM_ARM_VCPU_INIT) and 0xb0 (KVM_GET_REG_LIST), so he wanted to make the documentation follow the ioctl numbering scheme. That makes sense.

However, why do we have this gap there in the first place?


Alex