linux-kernel - Re: [PATCH v2 11/12] KVM: selftests / xen: don't explicitly set the vcpu

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Message-ID: <56dad458-8816-2de5-544e-a5e50c5ad2a2@xen.org>
Date:   Mon, 18 Sep 2023 14:26:36 +0100
From:   Paul Durrant <xadimgnik@...il.com>
To:     David Woodhouse <dwmw2@...radead.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Paul Durrant <pdurrant@...zon.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH v2 11/12] KVM: selftests / xen: don't explicitly set the
 vcpu_info address

On 18/09/2023 14:21, David Woodhouse wrote:
> On Mon, 2023-09-18 at 11:21 +0000, Paul Durrant wrote:
>> From: Paul Durrant <pdurrant@...zon.com>
>>
>> If the vCPU id is set and the shared_info is mapped using HVA then we can
>> infer that KVM has the ability to use a default vcpu_info mapping. Hence
>> we can stop setting the address of the vcpu_info structure.
> 
> Again that means we're not *testing* it any more when the test is run
> on newer kernels. Can we perhaps set it explicitly, after *half* the
> tests are done? Maybe to a *different* address than the default which
> is derived from the Xen vcpu_id? And check that the memcpy works right
> when we do?
> 

Ok. The VMM is currently responsible for that memcpy. Are you suggesting 
we push that into KVM too?

   Paul