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From: Oliver Upton <oliver.upton@linux.dev>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: "kvmarm@lists.linux.dev" <kvmarm@lists.linux.dev>,
	"maz@kernel.org" <maz@kernel.org>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"will@kernel.org" <will@kernel.org>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	yuzenghui <yuzenghui@huawei.com>,
	"Wangzhou (B)" <wangzhou1@hisilicon.com>,
	jiangkunkun <jiangkunkun@huawei.com>,
	Jonathan Cameron <jonathan.cameron@huawei.com>,
	Anthony Jebson <anthony.jebson@huawei.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Linuxarm <linuxarm@huawei.com>
Subject: Re: [RFC PATCH v2 1/3] KVM: arm64: Add hypercall support for retrieving migration targets
Date: Tue, 29 Oct 2024 21:39:14 -0700	[thread overview]
Message-ID: <ZyG4cjIscLqCT7Dx@linux.dev> (raw)
In-Reply-To: <d97cd23a1962460990a642ee8a653d2f@huawei.com>

On Tue, Oct 29, 2024 at 04:00:39PM +0000, Shameerali Kolothum Thodi wrote:
> > We can't treat a single register as both a signed quantity *and* a full
> > 64 bits of bitfields. Maybe just scrap the version and have this thing
> > either return a negative error or positive quantity of implementations.
> 
> Ok. I had  a look at PV_TIME_ST/ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID
> and got that idea. Separate registers make sense though.
> 
> Do we really need to skip the version number? The idea was to use that as a
> future proof for data format in case we realize that MIDR/REVIDR is not good
> enough for errata later.

That is definitely an approach we can take. The alternative I had in
mind was that we'd allocate a new function ID if we needed to break ABI
to correct shortcomings of the original interface.

-- 
Thanks,
Oliver


  reply	other threads:[~2024-10-30  4:41 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-24  9:40 [RFC PATCH v2 0/3] KVM: arm64: Errata management for VM Live migration Shameer Kolothum
2024-10-24  9:40 ` [RFC PATCH v2 1/3] KVM: arm64: Add hypercall support for retrieving migration targets Shameer Kolothum
2024-10-25  1:25   ` Oliver Upton
2024-10-29 16:00     ` Shameerali Kolothum Thodi
2024-10-30  4:39       ` Oliver Upton [this message]
2024-10-24  9:40 ` [RFC PATCH v2 2/3] KVM: arm64: Use hypercall to retrieve any " Shameer Kolothum
2024-10-24  9:40 ` [RFC PATCH v2 3/3] KVM: arm64: Enable errata based on migration target CPUs Shameer Kolothum
2024-10-25  1:36   ` Oliver Upton
2024-10-28 17:29     ` Shameerali Kolothum Thodi
2024-10-30  4:33       ` Oliver Upton

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