From:   Kechen Lu <kechenl@nvidia.com>
To:     Sean Christopherson <seanjc@google.com>
CC:     "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "wanpengli@tencent.com" <wanpengli@tencent.com>,
        "vkuznets@redhat.com" <vkuznets@redhat.com>,
        "mst@redhat.com" <mst@redhat.com>,
        Somdutta Roy <somduttar@nvidia.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [RFC PATCH v2 3/3] KVM: x86: add vCPU ioctl for HLT exits disable
 capability
Thread-Topic: [RFC PATCH v2 3/3] KVM: x86: add vCPU ioctl for HLT exits
 disable capability
Thread-Index: AQHX9koEtqUfpyHZkkeby8KEcdrzF6xc3GqAgAABPgCAAI/ZAA==
Date:   Tue, 11 Jan 2022 06:36:46 +0000
Message-ID: <DM6PR12MB3500BC3ADEB0AAD6D20AC1B6CA519@DM6PR12MB3500.namprd12.prod.outlook.com>
References: <20211221090449.15337-1-kechenl@nvidia.com>
 <20211221090449.15337-4-kechenl@nvidia.com> <Ydyda6K8FrFveZX7@google.com>
 <YdyediQZQPB7h/kU@google.com>
In-Reply-To: <YdyediQZQPB7h/kU@google.com>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?WkuweyMYu8Kg5uFwe69ZzEA+Qr1b2BgOWsiPsyqMoLmOLtYLicBmkAODtjD7?=
 =?us-ascii?Q?zLHk7Z307ifcEpYzqT4KJh4ELElvdTxAYHW9fNIQb31tRqKiQgRkW2al2cSp?=
 =?us-ascii?Q?RBo6cD65nKjZ/PA+yz8orwZFGa+DEKFQiAtT3LDlMQen+ZUcGXE05Kkk2m2u?=
 =?us-ascii?Q?jQasXu3sGG39hH5pkMbHVSrO3nShhtJnUbLxbS3rsk5muqH11IGeT+h8DbIJ?=
 =?us-ascii?Q?SM3D14L4NBr1OqV81IaseJlWQHyEeyhyBlAEya7lrr6LR5fufcYBZJIy8TtR?=
 =?us-ascii?Q?BkN4NgFgbTvS+ii1+JaQQXURebN7+r8+pDhLzBCzqqnl6KknkjYasY3EsI5F?=
 =?us-ascii?Q?Kf3lslLJxykjz3eoXtG1EIHHKo/lVYIEQnNoGLwYGHUk3e7y6Yr2DEj1ZJjB?=
 =?us-ascii?Q?STDJgpTpScabndbPUZAsdWf09A/qRdq4waBvQu61cpkGMbNKtsVxrFWHhsqp?=
 =?us-ascii?Q?+2YugcBbb7tYex50zAKOBTdQB5rklRNydv/NooKRAGG8Bi3KQ6mnO2mGYRts?=
 =?us-ascii?Q?I1vAEB6PtxYTMqdIUhQ4KzIBBSBMOYR/BGH6MalI+ybQsAhn/QkI+lo0g8tp?=
 =?us-ascii?Q?ectKxx9hAMLesP14iZN3jBNLWb8FSq+bD0bwmrPYIm8nO4jSZGPJMLjmmHoo?=
 =?us-ascii?Q?cUBcyPetsobt6G+ASCK67GrWQqNo2SOsoT3H2gb77TyYLSH27kMVsQro+9qw?=
 =?us-ascii?Q?y2+ceKy5cl2+mnCcZhJ0zUpUmxxfM0sHkc2I44sBn0zA/Aw2MONZqCsUEW53?=
 =?us-ascii?Q?yWcN7VfS6ju5MzAA5qZ83FAbitTXIO5ZCrqIFhJ1MCxjWVH25vGCZkEaHoyC?=
 =?us-ascii?Q?Ut7EyNzLsbKRVxrptWiKnmxb3k05CcU5sh5SxgNiieDOw0V7ZN16qe1RrOVn?=
 =?us-ascii?Q?2Jm7a95EayGuz5yysp6sbOcbeiK1bqWxxmTETFhe0J9YxNEC3fFpZqdm6sGz?=
 =?us-ascii?Q?yLNFJK9d2MSMzgio/QOahDfSZ2gm5iVSQmhY3fe2TBhuVFSV/m2d/fnb8+no?=
 =?us-ascii?Q?dAYopFT4elf1VZS2nUf3kYgaw/0XQCfqp4dC5yekhLaXk4iMz6a9a5BGL1kC?=
 =?us-ascii?Q?k0LVfUIKYNDno9yvf6I+0lqKogKFbTdql6CTtibNC+Cnae4Mk0qudqe0XSS7?=
 =?us-ascii?Q?p9vK5WrWtsmkKYuIYKSZE3NUuimh/cR9mQccxZYmFkCt2a7C1q48rbhojS+y?=
 =?us-ascii?Q?IjP2vCyJ/OdupPAeNhxy+nAXTXxK6PDXwbs9TgguOs1U8MdOIuuTqIG+aM5S?=
 =?us-ascii?Q?inxPv2dRJiGETa2YsSRA15ROlSlpGFnOmKInqCoxfLK1GQNDSZ5NIFfDTazj?=
 =?us-ascii?Q?bAlv4vZME7uJiMqF9li82fJVJc1FQAZoOvooEqtwlYqIZwOYYACLwcZ6XevQ?=
 =?us-ascii?Q?Y8IOWPCLrgbLA7ictwNuxKNI2hIh3miqcIMKoot3DM+gvTuxgmQIudOW3BwC?=
 =?us-ascii?Q?+vQ9t7Q7l1Sfka8BI20qO1ma3K2r4kikmifkvVLMPZba0rpyytnnkkzwcTbN?=
 =?us-ascii?Q?srNWcM/du4P4OQJsHzkVbjGl63MjcPvxZSLL3uI1CB155M+0tLOqiAQUQpj5?=
 =?us-ascii?Q?c7ptS/W8zE/5o6bAonMotffauFPGyd1YkpHc/LhB0HzhvWa6Mb8noYqFdyoS?=
 =?us-ascii?Q?l4TW2A5zhr1qD7o9XS+kfhU=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: Nvidia.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB3500.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 887825d7-c004-4eae-8c5a-08d9d4ccbd4d
X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Jan 2022 06:36:46.3403
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: K3S38qy46bIS2kfPXhyFu2epdgYRxiEa4uKBx7n/F1sTQZXtWMHyggOUutsou4/fpN3M8PWj67A5fQkxg5rhjg==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB3033
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


> -----Original Message-----
> From: Sean Christopherson <seanjc@google.com>
> Sent: Monday, January 10, 2022 1:01 PM
> To: Kechen Lu <kechenl@nvidia.com>
> Cc: kvm@vger.kernel.org; pbonzini@redhat.com; wanpengli@tencent.com;
> vkuznets@redhat.com; mst@redhat.com; Somdutta Roy
> <somduttar@nvidia.com>; linux-kernel@vger.kernel.org
> Subject: Re: [RFC PATCH v2 3/3] KVM: x86: add vCPU ioctl for HLT exits
> disable capability
>=20
> External email: Use caution opening links or attachments
>=20
>=20
> On Mon, Jan 10, 2022, Sean Christopherson wrote:
> > Does your use case require toggling intercepts?  Or is the configuratio=
n
> static?
> > If it's static, then the easiest thing would be to follow the per-VM
> > behavior so that there are no suprises.  If toggling is required, then
> > I think the best thing would be to add a prep patch to add an override
> > flag to the per-VM ioctl, and then share code between the per-VM and
> > per-vCPU paths for modifying the flags (attached as patch 0003).
>=20
> ...
>=20
> > If toggling is not required, then I still think it makes sense to add
> > a macro to handle propagating the capability args to the arch flags.
>=20
> Almost forgot.  Can you please add a selftests to verify whatever per-VM =
and
> per-vCPU behavior we end implementing?  Thanks!

Sure, will add selftests for per-VM and per-vCPU disable exits cap.

Thanks,
Kechen