diff mbox series

[v2,2/6] KVM: arm64: Add SMCCC paravirtualised lock calls

Message ID 20221104062105.4119003-3-usama.arif@bytedance.com
State New
Headers
Series KVM: arm64: implement vcpu_is_preempted check |

Commit Message

Usama Arif Nov. 4, 2022, 6:21 a.m. UTC 
  Add a new SMCCC compatible hypercalls for PV lock features:
  ARM_SMCCC_KVM_FUNC_PV_LOCK:   0xC6000002

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

Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
 arch/arm64/include/asm/pvlock-abi.h | 17 +++++++++++++++++
 include/linux/arm-smccc.h           |  8 ++++++++
 tools/include/linux/arm-smccc.h     |  8 ++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 arch/arm64/include/asm/pvlock-abi.h

Comments

Punit Agrawal Nov. 7, 2022, 5:58 p.m. UTC | #1 
Usama Arif <usama.arif@bytedance.com> writes:

> Add a new SMCCC compatible hypercalls for PV lock features:
>   ARM_SMCCC_KVM_FUNC_PV_LOCK:   0xC6000002
>
> Also add the header file which defines the ABI for the paravirtualized
> lock features we're about to add.
>
> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
> ---
>  arch/arm64/include/asm/pvlock-abi.h | 17 +++++++++++++++++
>  include/linux/arm-smccc.h           |  8 ++++++++
>  tools/include/linux/arm-smccc.h     |  8 ++++++++
>  3 files changed, 33 insertions(+)
>  create mode 100644 arch/arm64/include/asm/pvlock-abi.h
>
> diff --git a/arch/arm64/include/asm/pvlock-abi.h b/arch/arm64/include/asm/pvlock-abi.h
> new file mode 100644
> index 000000000000..3f4574071679
> --- /dev/null
> +++ b/arch/arm64/include/asm/pvlock-abi.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright(c) 2019 Huawei Technologies Co., Ltd
> + * Author: Zengruan Ye <yezengruan@huawei.com>
> + *         Usama Arif <usama.arif@bytedance.com>
> + */
> +
> +#ifndef __ASM_PVLOCK_ABI_H
> +#define __ASM_PVLOCK_ABI_H
> +
> +struct pvlock_vcpu_state {
> +	__le64 preempted;
> +	/* Structure must be 64 byte aligned, pad to that size */
> +	u8 padding[56];
> +} __packed;

For structure alignment, I'd have expected to see the use of "aligned"
attribute. Is there any benefit in using padding to achieve alignment?

[...]
Usama Arif Nov. 7, 2022, 6:08 p.m. UTC | #2 
On 07/11/2022 17:58, Punit Agrawal wrote:
> Usama Arif <usama.arif@bytedance.com> writes:
> 
>> Add a new SMCCC compatible hypercalls for PV lock features:
>>    ARM_SMCCC_KVM_FUNC_PV_LOCK:   0xC6000002
>>
>> Also add the header file which defines the ABI for the paravirtualized
>> lock features we're about to add.
>>
>> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
>> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
>> ---
>>   arch/arm64/include/asm/pvlock-abi.h | 17 +++++++++++++++++
>>   include/linux/arm-smccc.h           |  8 ++++++++
>>   tools/include/linux/arm-smccc.h     |  8 ++++++++
>>   3 files changed, 33 insertions(+)
>>   create mode 100644 arch/arm64/include/asm/pvlock-abi.h
>>
>> diff --git a/arch/arm64/include/asm/pvlock-abi.h b/arch/arm64/include/asm/pvlock-abi.h
>> new file mode 100644
>> index 000000000000..3f4574071679
>> --- /dev/null
>> +++ b/arch/arm64/include/asm/pvlock-abi.h
>> @@ -0,0 +1,17 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Copyright(c) 2019 Huawei Technologies Co., Ltd
>> + * Author: Zengruan Ye <yezengruan@huawei.com>
>> + *         Usama Arif <usama.arif@bytedance.com>
>> + */
>> +
>> +#ifndef __ASM_PVLOCK_ABI_H
>> +#define __ASM_PVLOCK_ABI_H
>> +
>> +struct pvlock_vcpu_state {
>> +	__le64 preempted;
>> +	/* Structure must be 64 byte aligned, pad to that size */
>> +	u8 padding[56];
>> +} __packed;
> 
> For structure alignment, I'd have expected to see the use of "aligned"
> attribute. Is there any benefit in using padding to achieve alignment?
> 
Just made it consistent with pvclock-abi.h. If its more appropriate, can 
change to aligned in next patchset:

diff --git a/arch/arm64/include/asm/pvlock-abi.h 
b/arch/arm64/include/asm/pvlock-abi.h
index 3f4574071679..bacec4cb927a 100644
--- a/arch/arm64/include/asm/pvlock-abi.h
+++ b/arch/arm64/include/asm/pvlock-abi.h
@@ -11,7 +11,6 @@
  struct pvlock_vcpu_state {
         __le64 preempted;
         /* Structure must be 64 byte aligned, pad to that size */
-       u8 padding[56];
-} __packed;
+} __attribute__((aligned(64)));


> [...]
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/pvlock-abi.h b/arch/arm64/include/asm/pvlock-abi.h
new file mode 100644
index 000000000000..3f4574071679
--- /dev/null
+++ b/arch/arm64/include/asm/pvlock-abi.h
@@ -0,0 +1,17 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ *         Usama Arif <usama.arif@bytedance.com>
+ */
+
+#ifndef __ASM_PVLOCK_ABI_H
+#define __ASM_PVLOCK_ABI_H
+
+struct pvlock_vcpu_state {
+	__le64 preempted;
+	/* Structure must be 64 byte aligned, pad to that size */
+	u8 padding[56];
+} __packed;
+
+#endif
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 220c8c60e021..104c10035b10 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -112,6 +112,7 @@ 
 /* KVM "vendor specific" services */
 #define ARM_SMCCC_KVM_FUNC_FEATURES		0
 #define ARM_SMCCC_KVM_FUNC_PTP			1
+#define ARM_SMCCC_KVM_FUNC_PV_LOCK		2
 #define ARM_SMCCC_KVM_FUNC_FEATURES_2		127
 #define ARM_SMCCC_KVM_NUM_FUNCS			128
 
@@ -151,6 +152,13 @@ 
 			   ARM_SMCCC_OWNER_STANDARD_HYP,	\
 			   0x21)
 
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,		\
+			   ARM_SMCCC_KVM_FUNC_PV_LOCK)
+
 /* TRNG entropy source calls (defined by ARM DEN0098) */
 #define ARM_SMCCC_TRNG_VERSION					\
 	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
diff --git a/tools/include/linux/arm-smccc.h b/tools/include/linux/arm-smccc.h
index 63ce9bebccd3..c21e539c0228 100644
--- a/tools/include/linux/arm-smccc.h
+++ b/tools/include/linux/arm-smccc.h
@@ -111,6 +111,7 @@ 
 /* KVM "vendor specific" services */
 #define ARM_SMCCC_KVM_FUNC_FEATURES		0
 #define ARM_SMCCC_KVM_FUNC_PTP			1
+#define ARM_SMCCC_KVM_FUNC_PV_LOCK		2
 #define ARM_SMCCC_KVM_FUNC_FEATURES_2		127
 #define ARM_SMCCC_KVM_NUM_FUNCS			128
 
@@ -150,6 +151,13 @@ 
 			   ARM_SMCCC_OWNER_STANDARD_HYP,	\
 			   0x21)
 
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,		\
+			   ARM_SMCCC_KVM_FUNC_PV_LOCK)
+
 /* TRNG entropy source calls (defined by ARM DEN0098) */
 #define ARM_SMCCC_TRNG_VERSION					\
 	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\