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@xxxxxxx>
>> ---
>> 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.
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