From: Marc Zyngier <maz@kernel.org>
To: Keqian Zhu <zhukeqian1@huawei.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Steven Price <steven.price@arm.com>,
wanghaibin.wang@huawei.com
Subject: Re: [PATCH 2/3] KVM: uapi: Remove KVM_DEV_TYPE_ARM_PV_TIME in kvm_device_type
Date: Mon, 17 Aug 2020 08:39:12 +0100 [thread overview]
Message-ID: <f97633b4a39c301f916bb76030dcabf0@kernel.org> (raw)
In-Reply-To: <20200817033729.10848-3-zhukeqian1@huawei.com>
On 2020-08-17 04:37, Keqian Zhu wrote:
> ARM64 PV-time ST is configured by userspace through vCPU attribute,
> and KVM_DEV_TYPE_ARM_PV_TIME is unused.
>
> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
> ---
> include/uapi/linux/kvm.h | 2 --
> tools/include/uapi/linux/kvm.h | 2 --
> 2 files changed, 4 deletions(-)
>
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 4fdf303..9a6b97e 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1258,8 +1258,6 @@ enum kvm_device_type {
> #define KVM_DEV_TYPE_ARM_VGIC_ITS KVM_DEV_TYPE_ARM_VGIC_ITS
> KVM_DEV_TYPE_XIVE,
> #define KVM_DEV_TYPE_XIVE KVM_DEV_TYPE_XIVE
> - KVM_DEV_TYPE_ARM_PV_TIME,
> -#define KVM_DEV_TYPE_ARM_PV_TIME KVM_DEV_TYPE_ARM_PV_TIME
> KVM_DEV_TYPE_MAX,
> };
>
> diff --git a/tools/include/uapi/linux/kvm.h
> b/tools/include/uapi/linux/kvm.h
> index 4fdf303..9a6b97e 100644
> --- a/tools/include/uapi/linux/kvm.h
> +++ b/tools/include/uapi/linux/kvm.h
> @@ -1258,8 +1258,6 @@ enum kvm_device_type {
> #define KVM_DEV_TYPE_ARM_VGIC_ITS KVM_DEV_TYPE_ARM_VGIC_ITS
> KVM_DEV_TYPE_XIVE,
> #define KVM_DEV_TYPE_XIVE KVM_DEV_TYPE_XIVE
> - KVM_DEV_TYPE_ARM_PV_TIME,
> -#define KVM_DEV_TYPE_ARM_PV_TIME KVM_DEV_TYPE_ARM_PV_TIME
> KVM_DEV_TYPE_MAX,
> };
No. You can't drop anything from UAPI, used or not. Doing so will
break the compilation of any userspace that, for any reason, references
this value. We cannot reuse this value in the future either, as it would
create a we wouldn't know which device to create.
It is pretty unfortunate that PV time has turned into such a train
wreck,
but that's what we have now, and it has to stay.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2020-08-17 7:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 3:37 [PATCH 0/3] KVM: arm64: Some fixes and code adjustments for pvtime ST Keqian Zhu
2020-08-17 3:37 ` [PATCH 1/3] KVM: arm64: Some fixes of PV-time interface document Keqian Zhu
2020-08-17 8:47 ` Andrew Jones
2020-08-17 9:02 ` zhukeqian
2020-08-17 9:39 ` Steven Price
2020-08-17 3:37 ` [PATCH 2/3] KVM: uapi: Remove KVM_DEV_TYPE_ARM_PV_TIME in kvm_device_type Keqian Zhu
2020-08-17 7:39 ` Marc Zyngier [this message]
2020-08-17 8:43 ` zhukeqian
2020-08-17 9:49 ` Steven Price
2020-08-17 10:56 ` zhukeqian
2020-08-17 3:37 ` [PATCH 3/3] KVM: arm64: Use kvm_write_guest_lock when init stolen time Keqian Zhu
2020-08-17 8:52 ` Andrew Jones
2020-08-17 9:53 ` Steven Price
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