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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?+Z9BcCLCNLcyYgZll6HCAZxClDGRJedQRp6vCM/0UkQqYhornfY/vhzOU3S/?= =?us-ascii?Q?iLB04G9KaLg0XKWjs3Wsubee9WWo31uPeHJE5CvqszePvFGOVGKE6aRYrKvm?= =?us-ascii?Q?eVWMHTwSaKxS4TmpgR8chPx1AJlzGW7LdoWuFGjkFW5+jAsBubCe38zH8GEG?= =?us-ascii?Q?2mXHacEkXYzn3v/TjFl3MSaen55bG0kiPDsHqCmaE13dld9t7S5U+Fgm/5Mf?= =?us-ascii?Q?gIFD4a+iTQ82gFuT+1fGxBedkwDC4C4mHigHSemZ5CJCGIT0qXPRRar42fwV?= =?us-ascii?Q?R90wliGsGXm+EFiYemjZc3tJ17Dx5s+AoLAWCHLQuTDg5DoN2nK+SbI5yTdq?= =?us-ascii?Q?HNgi4wwSpyekJCwAYEOfXVHdEwfupdkxy79qHbS/iLCkNSxnfqZ9oMlxEPoL?= =?us-ascii?Q?Y+31W/jDb5/NVQF9ZsXWaF3YxV1qfArgBowMvkaOFJzS9CaAzXzzCNQ+fDEF?= =?us-ascii?Q?9UcLuMcdYLiQHXVuQOY8V16V57FavLk1WkWZhWauszH0H68zsGbV0rGym7Kj?= =?us-ascii?Q?tSHawtS7ubnao2hcYsJnYP+1p09W5e+L4ZEMtZdTOXJShqkocj5C8yRI9p7G?= =?us-ascii?Q?qs9nQmR6gTfjMqS+bdFGO0SiVE7R5vqqqnNP8pGlcgIi0IKnwYGEbEuIzErN?= =?us-ascii?Q?Zw4CNAU0VHHHMimJUEFWuxEXPZoEbNRftJE/+CY6m1jVILO2kW+TXeBGsoaj?= =?us-ascii?Q?jwkFgwwlgICuG3tTc0QMVvvD2nWtHP7ni+xTTRjS79FGYbRgEoiBqUW14+Wt?= =?us-ascii?Q?5zvu4864B8m4Yz11ie605Cjk3PiMdUO29fM5aAh7I7RHazmCNJZSCtxCEK20?= =?us-ascii?Q?Awvc1N28hq8ZYGLiQvLU+EmCyMRXvRm0+TGeG9x+DivpzKNstnGKGH2daiba?= =?us-ascii?Q?iFNdjOUcWaxMQaXkJ0dIktiZsr0pqLOgkCqqVnQgoSp791UEpzAzCh66sLCk?= =?us-ascii?Q?Tgp5O5eLRB7kxNUdspJL4gYDK1+kAjOYcCvSs+e+zaxf1AVQ1B6Tgm4L+hcM?= =?us-ascii?Q?QLIwOwrVZAsHZ/3MLTw4PWLacBp3hHPbAWz93z82Vv6H9TKDGerjqBc2vFQn?= =?us-ascii?Q?Bp8cjBbsqY2Aj+t1wzZ8ukw2NSh1E77nQWPOZx2gD3li+BZpgRatK13TF90F?= =?us-ascii?Q?ZIEZRLsBrmBuY6lZZaAcN+aSzNr8/KWzqTMT/dQWJgjNDcR2fyX5yYCbTpDU?= =?us-ascii?Q?bbDOHVnqKjRvS1nrdP3dNvZLoH5TeYq/YOVdvXTZqfjpdFUvBfWHDrmB7J/n?= =?us-ascii?Q?Uo/C8mYSOyXm3LuUPxQRxtnnfxDmiBmQAJdilmD9CM2FxkwbL+YWywxI7lMw?= =?us-ascii?Q?RCs2bDKXlNtgaFlcl5jN7nLbxJ/TV5tZ6dfDL6I0ZWAyQNI85fJDYmHRYg0g?= =?us-ascii?Q?+Q9jiIbEcxX47iYNGhAtFgL5DFYrTOS26OjrFvH9LMc1zVgBfoPxxMjUg5Hn?= =?us-ascii?Q?cg90U/dqnh4OKJtffMQvHhrcvo5vWSrhoHDpV1yhbrz8H6WltZ/8Qy9X0k/f?= =?us-ascii?Q?0pdMPqN3i/MBIgbhEWrCFHtw07FH4GM/Gp8x6bYvVWQz5PZtJkiLGDxw4B/1?= =?us-ascii?Q?Q2y/Yq0/CLZyafRyW8EbaMbLvFu7roeilluSievlx6Af5kDq4KIFQoTROJYe?= =?us-ascii?Q?jQ=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 1ecf1dbb-1323-42e3-0747-08db24654899 X-MS-Exchange-CrossTenant-AuthSource: SA1PR11MB5923.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Mar 2023 08:22:43.3373 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 4KtYuAPKT4sirnF+TxYlElJvGkvQkA95QS2OXLuEUns6kX9o0Y4oUxwQNgy3IKriFfECnp8UHdZ610LlRYu70Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR11MB5054 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Mar 13, 2023 at 09:58:27AM -0700, Sean Christopherson wrote: > On Mon, Mar 13, 2023, Jason Chen CJ wrote: > > This patch set is part-5 of this RFC patches. It introduces VMX > > emulation for pKVM on Intel platform. > > > > Host VM wants the capability to run its guest, it needs VMX support. > > No, the host VM only needs a way to request pKVM to run a VM. If we go down the > rabbit hole of pKVM on x86, I think we should take the red pill[*] and go all the > way down said rabbit hole by heavily paravirtualizing the KVM=>pKVM interface. hi, Sean, Like I mentioned in the reply for "[RFC PATCH part-1 0/5] pKVM on Intel Platform Introduction", we hope VMX emulation can be there at least for normal VM support. > > Except for VMCALL vs. VMMCALL, it should be possible to eliminate all traces of > VMX and SVM from the interface. That means no VMCS emulation, no EPT shadowing, > etc. As a bonus, any paravirt stuff we do for pKVM x86 would also be usable for > KVM-on-KVM nested virtualization. > > E.g. an idea floating around my head is to add a paravirt paging interface for > KVM-on-KVM so that L1's (KVM-high in this RFC) doesn't need to maintain its own > TDP page tables. I haven't pursued that idea in any real capacity since most > nested virtualization use cases for KVM involve running an older L1 kernel and/or > a non-KVM L1 hypervisor, i.e. there's no concrete use case to justify the development > and maintenance cost. But if the PV code is "needed" by pKVM anyways... Yes, I agree, we could have performance & mem cost benefit by using paravirt stuff for KVM-on-KVM nested virtualization. May I know do I miss other benefit you saw? > > [*] You take the blue pill, the story ends, you wake up in your bed and believe > whatever you want to believe. You take the red pill, you stay in wonderland, > and I show you how deep the rabbit hole goes. > > -Morpheus -- Thanks Jason CJ Chen