Patchwork [05/12] KVM: arm64: Implement PV_FEATURES call

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Submitter Steven Price
Date Nov. 28, 2018, 2:45 p.m.
Message ID <20181128144527.44710-6-steven.price@arm.com>
Download mbox | patch
Permalink /patch/667171/
State New
Headers show

Comments

Steven Price - Nov. 28, 2018, 2:45 p.m.
This provides a mechanism for querying which paravirtualized features
are available in this hypervisor.

Also add the header file which defines the ABI for the paravirtualized
clock features we're about to add.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/include/asm/pvclock-abi.h | 32 ++++++++++++++++++++++++++++
 include/kvm/arm_pv.h                 | 28 ++++++++++++++++++++++++
 include/linux/arm-smccc.h            |  1 +
 virt/kvm/arm/hypercalls.c            |  9 ++++++++
 4 files changed, 70 insertions(+)
 create mode 100644 arch/arm64/include/asm/pvclock-abi.h
 create mode 100644 include/kvm/arm_pv.h
Mark Rutland - Dec. 10, 2018, 10:39 a.m.
On Wed, Nov 28, 2018 at 02:45:20PM +0000, Steven Price wrote:
> This provides a mechanism for querying which paravirtualized features
> are available in this hypervisor.
> 
> Also add the header file which defines the ABI for the paravirtualized
> clock features we're about to add.
> 
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
>  arch/arm64/include/asm/pvclock-abi.h | 32 ++++++++++++++++++++++++++++
>  include/kvm/arm_pv.h                 | 28 ++++++++++++++++++++++++
>  include/linux/arm-smccc.h            |  1 +
>  virt/kvm/arm/hypercalls.c            |  9 ++++++++
>  4 files changed, 70 insertions(+)
>  create mode 100644 arch/arm64/include/asm/pvclock-abi.h
>  create mode 100644 include/kvm/arm_pv.h
> 
> diff --git a/arch/arm64/include/asm/pvclock-abi.h b/arch/arm64/include/asm/pvclock-abi.h
> new file mode 100644
> index 000000000000..64ce041c8922
> --- /dev/null
> +++ b/arch/arm64/include/asm/pvclock-abi.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2018 Arm Ltd. */
> +
> +#ifndef __ASM_PVCLOCK_ABI_H
> +#define __ASM_PVCLOCK_ABI_H
> +
> +#include <kvm/arm_pv.h>
> +
> +struct pvclock_vm_time_info {
> +	__le32 revision;
> +	__le32 attributes;
> +	__le64 sequence_number;
> +	__le64 scale_mult;
> +	__le32 shift;
> +	__le32 reserved;
> +	__le64 native_freq;
> +	__le64 pv_freq;
> +	__le64 div_by_pv_freq_mult;
> +} __packed;
> +
> +struct pvclock_vcpu_stolen_time_info {
> +	__le32 revision;
> +	__le32 attributes;
> +	__le64 stolen_time;
> +	/* Structure must be 64 byte aligned, pad to that size */
> +	u8 padding[48];
> +} __packed;
> +
> +#define PV_VM_TIME_NOT_SUPPORTED	-1
> +#define PV_VM_TIME_INVALID_PARAMETERS	-2

Could you please add a comment describing that these are defined in ARM
DEN0057A?

> +
> +#endif
> diff --git a/include/kvm/arm_pv.h b/include/kvm/arm_pv.h
> new file mode 100644
> index 000000000000..19d2dafff31a
> --- /dev/null
> +++ b/include/kvm/arm_pv.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0
> + * Copyright (C) 2018 Arm Ltd.
> + */
> +
> +#ifndef __KVM_ARM_PV_H
> +#define __KVM_ARM_PV_H
> +
> +#include <linux/arm-smccc.h>
> +
> +#define ARM_SMCCC_HV_PV_FEATURES					\
> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
> +			   ARM_SMCCC_SMC_64,			\
> +			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
> +			   0x20)
> +
> +#define ARM_SMCCC_HV_PV_TIME_LPT					\
> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
> +			   ARM_SMCCC_SMC_64,			\
> +			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
> +			   0x21)
> +
> +#define ARM_SMCCC_HV_PV_TIME_ST					\
> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
> +			   ARM_SMCCC_SMC_64,			\
> +			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
> +			   0x22)
> +
> +#endif /* __KVM_ARM_PV_H */

Do these need to live in a separate header, away from the struct
definitions?

I'd be happy for these to live in <linux/arm-smccc.h>, given they're
standard calls.

As before, a comment referring to ARM DEN0057A would be nice.


> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index b047009e7a0a..4e0866cc48c0 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -54,6 +54,7 @@
>  #define ARM_SMCCC_OWNER_SIP		2
>  #define ARM_SMCCC_OWNER_OEM		3
>  #define ARM_SMCCC_OWNER_STANDARD	4
> +#define ARM_SMCCC_OWNER_HYP_STANDARD	5

Minor nit, but could we make that STANDARD_HYP?

>  #define ARM_SMCCC_OWNER_TRUSTED_APP	48
>  #define ARM_SMCCC_OWNER_TRUSTED_APP_END	49
>  #define ARM_SMCCC_OWNER_TRUSTED_OS	50
> diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c
> index 153aa7642100..ba13b798f0f8 100644
> --- a/virt/kvm/arm/hypercalls.c
> +++ b/virt/kvm/arm/hypercalls.c
> @@ -5,6 +5,7 @@
>  #include <linux/kvm_host.h>
>  
>  #include <asm/kvm_emulate.h>
> +#include <asm/pvclock-abi.h>
>  
>  #include <kvm/arm_hypercalls.h>
>  #include <kvm/arm_psci.h>
> @@ -40,6 +41,14 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>  				break;
>  			}
>  			break;
> +		case ARM_SMCCC_HV_PV_FEATURES:
> +			val = SMCCC_RET_SUCCESS;
> +			break;
> +		}
> +		break;
> +	case ARM_SMCCC_HV_PV_FEATURES:
> +		feature = smccc_get_arg1(vcpu);
> +		switch (feature) {
>  		}

IIUC, at this point in time, this happens to always return
SMCCC_RET_NOT_SUPPORTED.

If you leave this part out of the patch, and add it as required, this
patch is purely adding definitions, which would be a bit nicer for
review.

Thanks,
Mark.
Steven Price - Dec. 10, 2018, 2:20 p.m.
On 10/12/2018 10:39, Mark Rutland wrote:
> On Wed, Nov 28, 2018 at 02:45:20PM +0000, Steven Price wrote:
>> This provides a mechanism for querying which paravirtualized features
>> are available in this hypervisor.
>>
>> Also add the header file which defines the ABI for the paravirtualized
>> clock features we're about to add.
>>
>> Signed-off-by: Steven Price <steven.price@arm.com>
>> ---
>>  arch/arm64/include/asm/pvclock-abi.h | 32 ++++++++++++++++++++++++++++
>>  include/kvm/arm_pv.h                 | 28 ++++++++++++++++++++++++
>>  include/linux/arm-smccc.h            |  1 +
>>  virt/kvm/arm/hypercalls.c            |  9 ++++++++
>>  4 files changed, 70 insertions(+)
>>  create mode 100644 arch/arm64/include/asm/pvclock-abi.h
>>  create mode 100644 include/kvm/arm_pv.h
>>
>> diff --git a/arch/arm64/include/asm/pvclock-abi.h b/arch/arm64/include/asm/pvclock-abi.h
>> new file mode 100644
>> index 000000000000..64ce041c8922
>> --- /dev/null
>> +++ b/arch/arm64/include/asm/pvclock-abi.h
>> @@ -0,0 +1,32 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/* Copyright (C) 2018 Arm Ltd. */
>> +
>> +#ifndef __ASM_PVCLOCK_ABI_H
>> +#define __ASM_PVCLOCK_ABI_H
>> +
>> +#include <kvm/arm_pv.h>
>> +
>> +struct pvclock_vm_time_info {
>> +	__le32 revision;
>> +	__le32 attributes;
>> +	__le64 sequence_number;
>> +	__le64 scale_mult;
>> +	__le32 shift;
>> +	__le32 reserved;
>> +	__le64 native_freq;
>> +	__le64 pv_freq;
>> +	__le64 div_by_pv_freq_mult;
>> +} __packed;
>> +
>> +struct pvclock_vcpu_stolen_time_info {
>> +	__le32 revision;
>> +	__le32 attributes;
>> +	__le64 stolen_time;
>> +	/* Structure must be 64 byte aligned, pad to that size */
>> +	u8 padding[48];
>> +} __packed;
>> +
>> +#define PV_VM_TIME_NOT_SUPPORTED	-1
>> +#define PV_VM_TIME_INVALID_PARAMETERS	-2
> 
> Could you please add a comment describing that these are defined in ARM
> DEN0057A?

No problem.

>> +
>> +#endif
>> diff --git a/include/kvm/arm_pv.h b/include/kvm/arm_pv.h
>> new file mode 100644
>> index 000000000000..19d2dafff31a
>> --- /dev/null
>> +++ b/include/kvm/arm_pv.h
>> @@ -0,0 +1,28 @@
>> +/* SPDX-License-Identifier: GPL-2.0
>> + * Copyright (C) 2018 Arm Ltd.
>> + */
>> +
>> +#ifndef __KVM_ARM_PV_H
>> +#define __KVM_ARM_PV_H
>> +
>> +#include <linux/arm-smccc.h>
>> +
>> +#define ARM_SMCCC_HV_PV_FEATURES					\
>> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
>> +			   ARM_SMCCC_SMC_64,			\
>> +			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
>> +			   0x20)
>> +
>> +#define ARM_SMCCC_HV_PV_TIME_LPT					\
>> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
>> +			   ARM_SMCCC_SMC_64,			\
>> +			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
>> +			   0x21)
>> +
>> +#define ARM_SMCCC_HV_PV_TIME_ST					\
>> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
>> +			   ARM_SMCCC_SMC_64,			\
>> +			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
>> +			   0x22)
>> +
>> +#endif /* __KVM_ARM_PV_H */
> 
> Do these need to live in a separate header, away from the struct
> definitions?
> 
> I'd be happy for these to live in <linux/arm-smccc.h>, given they're
> standard calls.

I'll move them to linux/arm-smccc.h - I didn't want to place them in
pvclock-abi.h as it seemed wrong to pull that into the generic SMCCC
code which doesn't care about these structures.

> As before, a comment referring to ARM DEN0057A would be nice.

Will add

>> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
>> index b047009e7a0a..4e0866cc48c0 100644
>> --- a/include/linux/arm-smccc.h
>> +++ b/include/linux/arm-smccc.h
>> @@ -54,6 +54,7 @@
>>  #define ARM_SMCCC_OWNER_SIP		2
>>  #define ARM_SMCCC_OWNER_OEM		3
>>  #define ARM_SMCCC_OWNER_STANDARD	4
>> +#define ARM_SMCCC_OWNER_HYP_STANDARD	5
> 
> Minor nit, but could we make that STANDARD_HYP?

Sure

>>  #define ARM_SMCCC_OWNER_TRUSTED_APP	48
>>  #define ARM_SMCCC_OWNER_TRUSTED_APP_END	49
>>  #define ARM_SMCCC_OWNER_TRUSTED_OS	50
>> diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c
>> index 153aa7642100..ba13b798f0f8 100644
>> --- a/virt/kvm/arm/hypercalls.c
>> +++ b/virt/kvm/arm/hypercalls.c
>> @@ -5,6 +5,7 @@
>>  #include <linux/kvm_host.h>
>>  
>>  #include <asm/kvm_emulate.h>
>> +#include <asm/pvclock-abi.h>
>>  
>>  #include <kvm/arm_hypercalls.h>
>>  #include <kvm/arm_psci.h>
>> @@ -40,6 +41,14 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>>  				break;
>>  			}
>>  			break;
>> +		case ARM_SMCCC_HV_PV_FEATURES:
>> +			val = SMCCC_RET_SUCCESS;
>> +			break;
>> +		}
>> +		break;
>> +	case ARM_SMCCC_HV_PV_FEATURES:
>> +		feature = smccc_get_arg1(vcpu);
>> +		switch (feature) {
>>  		}
> 
> IIUC, at this point in time, this happens to always return
> SMCCC_RET_NOT_SUPPORTED.

Yes, this is because on an oddity in the specification that I'm tempted
to ignore. I originally had PV_FEATURES (only) in the switch in this
patch. However the specification states:

  If PV_func_id identifies  PV_FEATURES this function can return:
  • NOT_SUPPORTED (-1) to indicate that all functions in this
    specification are not supported.
  • SUCCESS (0) to indicate that one or more
    paravirtualization functions are supported.

Since by this patch we haven't reached "one or more" functions a strict
reading of the specification says that even PV_FEATURES should be
returning NOT_SUPPORTED.

> If you leave this part out of the patch, and add it as required, this
> patch is purely adding definitions, which would be a bit nicer for
> review.

Before getting lost in the above wording the specification I had tried
to make the LPT and stolen time patches not dependent on each other.
Given your other comments (in reply to the cover letter), I think I'll
merge this chunk with the first stolen time patch and put all the stolen
time patches first.

Thanks,

Steve

> Thanks,
> Mark.
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
>

Patch

diff --git a/arch/arm64/include/asm/pvclock-abi.h b/arch/arm64/include/asm/pvclock-abi.h
new file mode 100644
index 000000000000..64ce041c8922
--- /dev/null
+++ b/arch/arm64/include/asm/pvclock-abi.h
@@ -0,0 +1,32 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018 Arm Ltd. */
+
+#ifndef __ASM_PVCLOCK_ABI_H
+#define __ASM_PVCLOCK_ABI_H
+
+#include <kvm/arm_pv.h>
+
+struct pvclock_vm_time_info {
+	__le32 revision;
+	__le32 attributes;
+	__le64 sequence_number;
+	__le64 scale_mult;
+	__le32 shift;
+	__le32 reserved;
+	__le64 native_freq;
+	__le64 pv_freq;
+	__le64 div_by_pv_freq_mult;
+} __packed;
+
+struct pvclock_vcpu_stolen_time_info {
+	__le32 revision;
+	__le32 attributes;
+	__le64 stolen_time;
+	/* Structure must be 64 byte aligned, pad to that size */
+	u8 padding[48];
+} __packed;
+
+#define PV_VM_TIME_NOT_SUPPORTED	-1
+#define PV_VM_TIME_INVALID_PARAMETERS	-2
+
+#endif
diff --git a/include/kvm/arm_pv.h b/include/kvm/arm_pv.h
new file mode 100644
index 000000000000..19d2dafff31a
--- /dev/null
+++ b/include/kvm/arm_pv.h
@@ -0,0 +1,28 @@ 
+/* SPDX-License-Identifier: GPL-2.0
+ * Copyright (C) 2018 Arm Ltd.
+ */
+
+#ifndef __KVM_ARM_PV_H
+#define __KVM_ARM_PV_H
+
+#include <linux/arm-smccc.h>
+
+#define ARM_SMCCC_HV_PV_FEATURES					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
+			   0x20)
+
+#define ARM_SMCCC_HV_PV_TIME_LPT					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
+			   0x21)
+
+#define ARM_SMCCC_HV_PV_TIME_ST					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_HYP_STANDARD,	\
+			   0x22)
+
+#endif /* __KVM_ARM_PV_H */
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index b047009e7a0a..4e0866cc48c0 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -54,6 +54,7 @@ 
 #define ARM_SMCCC_OWNER_SIP		2
 #define ARM_SMCCC_OWNER_OEM		3
 #define ARM_SMCCC_OWNER_STANDARD	4
+#define ARM_SMCCC_OWNER_HYP_STANDARD	5
 #define ARM_SMCCC_OWNER_TRUSTED_APP	48
 #define ARM_SMCCC_OWNER_TRUSTED_APP_END	49
 #define ARM_SMCCC_OWNER_TRUSTED_OS	50
diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c
index 153aa7642100..ba13b798f0f8 100644
--- a/virt/kvm/arm/hypercalls.c
+++ b/virt/kvm/arm/hypercalls.c
@@ -5,6 +5,7 @@ 
 #include <linux/kvm_host.h>
 
 #include <asm/kvm_emulate.h>
+#include <asm/pvclock-abi.h>
 
 #include <kvm/arm_hypercalls.h>
 #include <kvm/arm_psci.h>
@@ -40,6 +41,14 @@  int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 				break;
 			}
 			break;
+		case ARM_SMCCC_HV_PV_FEATURES:
+			val = SMCCC_RET_SUCCESS;
+			break;
+		}
+		break;
+	case ARM_SMCCC_HV_PV_FEATURES:
+		feature = smccc_get_arg1(vcpu);
+		switch (feature) {
 		}
 		break;
 	default: