From: Paolo Bonzini <pbonzini@redhat.com>
To: David Woodhouse <dwmw2@infradead.org>, kvm@vger.kernel.org
Cc: Ankur Arora <ankur.a.arora@oracle.com>,
Joao Martins <joao.m.martins@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Sean Christopherson <seanjc@google.com>,
graf@amazon.com, iaslan@amazon.de, pdurrant@amazon.com,
aagch@amazon.com, fandree@amazon.com, hch@infradead.org
Subject: Re: [PATCH v5 15/16] KVM: Add documentation for Xen hypercall and shared_info updates
Date: Thu, 28 Jan 2021 13:18:16 +0100 [thread overview]
Message-ID: <e79d508e-454f-f34e-018b-e6b63fe3d825@redhat.com> (raw)
In-Reply-To: <20210111195725.4601-16-dwmw2@infradead.org>
On 11/01/21 20:57, David Woodhouse wrote:
>
> +
> +KVM_XEN_ATTR_TYPE_LONG_MODE
> + Sets the ABI mode of the VM to 32-bit or 64-bit (long mode). This
> + determines the layout of the shared info pages exposed to the VM.
> +
> +KVM_XEN_ATTR_TYPE_SHARED_INFO
> + Sets the guest physical frame number at which the Xen "shared info"
> + page resides. Note that although Xen places vcpu_info for the first
> + 32 vCPUs in the shared_info page, KVM does not automatically do so
> + and requires that KVM_XEN_ATTR_TYPE_VCPU_INFO be used explicitly
> + even when the vcpu_info for a given vCPU resides at the "default"
> + location in the shared_info page. This is because KVM is not aware
> + of the Xen CPU id which is used as the index into the vcpu_info[]
> + array, so cannot know the correct default location.
> +
> +KVM_XEN_ATTR_TYPE_VCPU_INFO
> + Sets the guest physical address of the vcpu_info for a given vCPU.
> +
> +KVM_XEN_ATTR_TYPE_VCPU_TIME_INFO
> + Sets the guest physical address of an additional pvclock structure
> + for a given vCPU. This is typically used for guest vsyscall support.
> +
> +KVM_XEN_ATTR_TYPE_VCPU_RUNSTATE
> + Sets the guest physical address of the vcpu_runstate_info for a given
> + vCPU. This is how a Xen guest tracks CPU state such as steal time.
> +
My only qualm is really that the userspace API is really ugly.
Can you just have both a VM and a VCPU ioctl (so no vcpu_id to pass!),
add a generous padding to the struct, and just get everything out with a
single ioctl without having to pass in a type?
Paolo
next prev parent reply other threads:[~2021-01-28 12:20 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-11 19:57 [PATCH v5 00/16] KVM: Add minimal support for Xen HVM guests David Woodhouse
2021-01-11 19:57 ` [PATCH v5 01/16] KVM: x86/xen: fix Xen hypercall page msr handling David Woodhouse
2021-01-11 19:57 ` [PATCH v5 02/16] KVM: x86/xen: intercept xen hypercalls if enabled David Woodhouse
2021-01-11 23:42 ` kernel test robot
2021-01-28 12:21 ` Paolo Bonzini
2021-01-11 19:57 ` [PATCH v5 03/16] KVM: x86/xen: Fix coexistence of Xen and Hyper-V hypercalls David Woodhouse
2021-01-11 19:57 ` [PATCH v5 04/16] KVM: x86/xen: add KVM_XEN_HVM_SET_ATTR/KVM_XEN_HVM_GET_ATTR David Woodhouse
2021-01-11 19:57 ` [PATCH v5 05/16] KVM: x86/xen: latch long_mode when hypercall page is set up David Woodhouse
2021-01-11 19:57 ` [PATCH v5 06/16] KVM: x86/xen: add definitions of compat_shared_info, compat_vcpu_info David Woodhouse
2021-01-11 19:57 ` [PATCH v5 07/16] KVM: x86/xen: register shared_info page David Woodhouse
2021-01-11 19:57 ` [PATCH v5 08/16] xen: add wc_sec_hi to struct shared_info David Woodhouse
2021-01-11 19:57 ` [PATCH v5 09/16] KVM: x86/xen: update wallclock region David Woodhouse
2021-01-11 19:57 ` [PATCH v5 10/16] KVM: x86/xen: register vcpu info David Woodhouse
2021-01-11 19:57 ` [PATCH v5 11/16] KVM: x86/xen: setup pvclock updates David Woodhouse
2021-01-11 19:57 ` [PATCH v5 12/16] KVM: x86/xen: register vcpu time info region David Woodhouse
2021-01-11 19:57 ` [PATCH v5 13/16] KVM: x86/xen: register runstate info David Woodhouse
2021-01-28 12:15 ` Paolo Bonzini
2021-01-11 19:57 ` [PATCH v5 14/16] KVM: x86: declare Xen HVM shared info capability and add test case David Woodhouse
2021-01-11 19:57 ` [PATCH v5 15/16] KVM: Add documentation for Xen hypercall and shared_info updates David Woodhouse
2021-01-28 12:18 ` Paolo Bonzini [this message]
2021-01-28 16:49 ` David Woodhouse
2021-01-28 17:06 ` Paolo Bonzini
[not found] ` <f9b2b4e613ea4e6dd1f253f5092254d121c93c07.camel@infradead.org>
2021-01-29 7:59 ` Paolo Bonzini
2021-01-11 19:57 ` [PATCH v5 16/16] KVM: x86/xen: Add event channel interrupt vector upcall David Woodhouse
2021-01-28 12:43 ` Paolo Bonzini
2021-01-28 15:35 ` David Woodhouse
2021-01-28 17:01 ` Paolo Bonzini
2021-01-29 17:33 ` David Woodhouse
2021-01-29 19:19 ` Paolo Bonzini
2021-01-30 13:01 ` David Woodhouse
2021-01-21 11:56 ` [PATCH v5 17/16] KVM: x86/xen: Fix initialisation of gfn caches for Xen shared pages David Woodhouse
2021-01-28 12:45 ` [PATCH v5 00/16] KVM: Add minimal support for Xen HVM guests Paolo Bonzini
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