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From: Kai Huang <kai.huang@intel.com>
To: Jarkko Sakkinen <jarkko@kernel.org>
Cc: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org,
	seanjc@google.com, luto@kernel.org, dave.hansen@intel.com,
	haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de,
	tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com
Subject: Re: [RFC PATCH 03/23] x86/sgx: Introduce virtual EPC for use by KVM guests
Date: Tue, 12 Jan 2021 15:03:09 +1300	[thread overview]
Message-ID: <20210112150309.4ca3f915f7dd4d1dbd251afa@intel.com> (raw)
In-Reply-To: <X/0AX7B5mU2DMVaO@kernel.org>

On Tue, 12 Jan 2021 03:50:23 +0200 Jarkko Sakkinen wrote:
> On Tue, Jan 12, 2021 at 01:56:54PM +1300, Kai Huang wrote:
> > On Tue, 12 Jan 2021 01:38:23 +0200 Jarkko Sakkinen wrote:
> > > On Wed, Jan 06, 2021 at 02:55:20PM +1300, Kai Huang wrote:
> > > > From: Sean Christopherson <sean.j.christopherson@intel.com>
> > > > 
> > > > Add a misc device /dev/sgx_virt_epc to allow userspace to allocate "raw"
> > > > EPC without an associated enclave.  The intended and only known use case
> > > > for raw EPC allocation is to expose EPC to a KVM guest, hence the
> > > > virt_epc moniker, virt.{c,h} files and X86_SGX_VIRTUALIZATION Kconfig.
> > > > 
> > > > Modify sgx_init() to always try to initialize virtual EPC driver, even
> > > > when SGX driver is disabled due to SGX Launch Control is in locked mode,
> > > > or not present at all, since SGX virtualization allows to expose SGX to
> > > > guests that support non-LC configurations.
> > > > 
> > > > Implement the "raw" EPC allocation in the x86 core-SGX subsystem via
> > > > /dev/sgx_virt_epc rather than in KVM. Doing so has two major advantages:
> > > > 
> > > >   - Does not require changes to KVM's uAPI, e.g. EPC gets handled as
> > > >     just another memory backend for guests.
> > > > 
> > > >   - EPC management is wholly contained in the SGX subsystem, e.g. SGX
> > > >     does not have to export any symbols, changes to reclaim flows don't
> > > >     need to be routed through KVM, SGX's dirty laundry doesn't have to
> > > >     get aired out for the world to see, and so on and so forth.
> > > > 
> > > > The virtual EPC allocated to guests is currently not reclaimable, due to
> > > > oversubscription of EPC for KVM guests is not currently supported. Due
> > > > to the complications of handling reclaim conflicts between guest and
> > > > host, KVM EPC oversubscription is significantly more complex than basic
> > > > support for SGX virtualization.
> > > > 
> > > > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > > > Co-developed-by: Kai Huang <kai.huang@intel.com>
> > > > Signed-off-by: Kai Huang <kai.huang@intel.com>
> > > 
> > > The commit message does not describe the code changes. It should
> > > have an understandable explanation of fops. There is nothing about
> > > the implementation right now.
> > 
> > Thanks for feedback. Does "understabdable explanation of fops" mean I
> > should add one sentence to say, for instance: "userspace hypervisor should open
> > the /dev/sgx_virt_epc, use mmap() to get a valid address range, and then use
> > that address range to create KVM memory region"?
> > 
> > Or should I include an example of how to use /dev/sgx_virt_epc in userspace, for
> > instance, below?
> > 
> > 	fd = open("/dev/sgx_virt_epc", O_RDWR);
> > 	void *addr = mmap(NULL, size, ..., fd);
> > 	/* userspace hypervisor uses addr, size to create KVM memory slot */
> > 	...
> 
> I would suggest just to describe them in few sentences. Just write
> how you understand them in one paragraph.

Will do. Thanks.


  reply	other threads:[~2021-01-12  2:04 UTC|newest]

Thread overview: 111+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-06  1:55 [RFC PATCH 00/23] KVM SGX virtualization support Kai Huang
2021-01-06  1:55 ` [RFC PATCH 01/23] x86/sgx: Split out adding EPC page to free list to separate helper Kai Huang
2021-01-11 22:38   ` Jarkko Sakkinen
2021-01-12  0:19     ` Kai Huang
2021-01-12 21:45       ` Sean Christopherson
2021-01-13  1:15         ` Kai Huang
2021-01-13 17:05         ` Jarkko Sakkinen
2021-01-06  1:55 ` [RFC PATCH 02/23] x86/sgx: Add enum for SGX_CHILD_PRESENT error code Kai Huang
2021-01-06 18:28   ` Dave Hansen
2021-01-06 21:40     ` Kai Huang
2021-01-12  0:26     ` Jarkko Sakkinen
2021-01-11 23:32   ` Jarkko Sakkinen
2021-01-12  0:16     ` Kai Huang
2021-01-12  1:46       ` Jarkko Sakkinen
2021-01-06  1:55 ` [RFC PATCH 03/23] x86/sgx: Introduce virtual EPC for use by KVM guests Kai Huang
2021-01-06 19:35   ` Dave Hansen
2021-01-06 20:35     ` Sean Christopherson
2021-01-07  0:47       ` Kai Huang
2021-01-07  0:52         ` Dave Hansen
2021-01-07  1:38           ` Kai Huang
2021-01-07  5:00             ` Dave Hansen
2021-01-07  1:42     ` Kai Huang
2021-01-07  5:02       ` Dave Hansen
2021-01-15 14:07         ` Kai Huang
2021-01-15 15:39           ` Dave Hansen
2021-01-15 21:33             ` Kai Huang
2021-01-15 21:45               ` Sean Christopherson
2021-01-15 22:30                 ` Kai Huang
2021-01-11 23:38   ` Jarkko Sakkinen
2021-01-12  0:56     ` Kai Huang
2021-01-12  1:50       ` Jarkko Sakkinen
2021-01-12  2:03         ` Kai Huang [this message]
2021-01-06  1:55 ` [RFC PATCH 04/23] x86/cpufeatures: Add SGX1 and SGX2 sub-features Kai Huang
2021-01-06 19:39   ` Dave Hansen
2021-01-06 22:12     ` Kai Huang
2021-01-06 22:21       ` Dave Hansen
2021-01-06 22:56         ` Kai Huang
2021-01-06 23:19           ` Sean Christopherson
2021-01-06 23:33             ` Dave Hansen
2021-01-06 23:56             ` Kai Huang
2021-01-06 23:40         ` Kai Huang
2021-01-06 23:43           ` Dave Hansen
2021-01-06 23:56             ` Kai Huang
2021-01-06 22:15   ` Borislav Petkov
2021-01-06 23:09     ` Kai Huang
2021-01-07  6:41       ` Borislav Petkov
2021-01-08  2:00         ` Kai Huang
2021-01-08  5:10           ` Dave Hansen
2021-01-08  7:03             ` Kai Huang
2021-01-08  7:17               ` Borislav Petkov
2021-01-08  8:06                 ` Kai Huang
2021-01-08  8:13                   ` Borislav Petkov
2021-01-08  9:00                     ` Kai Huang
2021-01-08 23:55                 ` Sean Christopherson
2021-01-09  0:35                   ` Borislav Petkov
2021-01-09  1:01                     ` Sean Christopherson
2021-01-09  1:19                   ` Borislav Petkov
2021-01-11 17:54                     ` Sean Christopherson
2021-01-11 19:09                       ` Borislav Petkov
2021-01-11 19:20                         ` Sean Christopherson
2021-01-12  2:01                           ` Kai Huang
2021-01-12 12:13                           ` Borislav Petkov
2021-01-12 17:15                             ` Sean Christopherson
2021-01-12 17:51                               ` Borislav Petkov
2021-01-12 21:07                                 ` Kai Huang
2021-01-12 23:17                                   ` Sean Christopherson
2021-01-13  1:05                                     ` Kai Huang
2021-01-11 23:39   ` Jarkko Sakkinen
2021-01-06  1:55 ` [RFC PATCH 05/23] x86/cpu/intel: Allow SGX virtualization without Launch Control support Kai Huang
2021-01-06 19:54   ` Dave Hansen
2021-01-06 22:34     ` Kai Huang
2021-01-06 22:38       ` Dave Hansen
2021-01-06  1:56 ` [RFC PATCH 06/23] x86/sgx: Expose SGX architectural definitions to the kernel Kai Huang
2021-01-06  1:56 ` [RFC PATCH 07/23] x86/sgx: Move ENCLS leaf definitions to sgx_arch.h Kai Huang
2021-01-06  1:56 ` [RFC PATCH 08/23] x86/sgx: Add SGX2 ENCLS leaf definitions (EAUG, EMODPR and EMODT) Kai Huang
2021-01-06  1:56 ` [RFC PATCH 09/23] x86/sgx: Add encls_faulted() helper Kai Huang
2021-01-06  1:56 ` [RFC PATCH 10/23] x86/sgx: Add helper to update SGX_LEPUBKEYHASHn MSRs Kai Huang
2021-01-06 19:56   ` Dave Hansen
2021-01-06  1:56 ` [RFC PATCH 11/23] x86/sgx: Add helpers to expose ECREATE and EINIT to KVM Kai Huang
2021-01-06 20:12   ` Dave Hansen
2021-01-06 21:04     ` Sean Christopherson
2021-01-06 21:23       ` Dave Hansen
2021-01-06 22:58         ` Kai Huang
2021-01-06  1:56 ` [RFC PATCH 12/23] x86/sgx: Move provisioning device creation out of SGX driver Kai Huang
2021-01-06  1:56 ` [RFC PATCH 13/23] KVM: VMX: Convert vcpu_vmx.exit_reason to a union Kai Huang
2021-01-06  1:56 ` [RFC PATCH 14/23] KVM: x86: Export kvm_mmu_gva_to_gpa_{read,write}() for SGX (VMX) Kai Huang
2021-01-06  1:56 ` [RFC PATCH 15/23] KVM: x86: Define new #PF SGX error code bit Kai Huang
2021-01-06  1:56 ` [RFC PATCH 16/23] KVM: x86: Add SGX feature leaf to reverse CPUID lookup Kai Huang
2021-01-06  1:56 ` [RFC PATCH 17/23] KVM: VMX: Add basic handling of VM-Exit from SGX enclave Kai Huang
2021-01-06  1:56 ` [RFC PATCH 18/23] KVM: VMX: Frame in ENCLS handler for SGX virtualization Kai Huang
2021-01-06  1:56 ` [RFC PATCH 19/23] KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions Kai Huang
2021-01-06  1:56 ` [RFC PATCH 20/23] KVM: VMX: Add emulation of SGX Launch Control LE hash MSRs Kai Huang
2021-01-06  1:56 ` [RFC PATCH 21/23] KVM: VMX: Add ENCLS[EINIT] handler to support SGX Launch Control (LC) Kai Huang
2021-01-06  1:56 ` [RFC PATCH 22/23] KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC Kai Huang
2021-01-06  1:58 ` [RFC PATCH 23/23] KVM: x86: Add capability to grant VM access to privileged SGX attribute Kai Huang
2021-01-06  2:22 ` [RFC PATCH 00/23] KVM SGX virtualization support Kai Huang
2021-01-06 17:07 ` Dave Hansen
2021-01-07  0:34   ` Kai Huang
2021-01-07  0:48     ` Dave Hansen
2021-01-07  1:50       ` Kai Huang
2021-01-07 16:14         ` Sean Christopherson
2021-01-08  2:16           ` Kai Huang
2021-01-11 17:20 ` Jarkko Sakkinen
2021-01-11 18:37   ` Sean Christopherson
2021-01-12  1:58     ` Jarkko Sakkinen
2021-01-12  1:14   ` Kai Huang
2021-01-12  2:02     ` Jarkko Sakkinen
2021-01-12  2:07       ` Kai Huang
2021-01-15 14:43         ` Kai Huang
2021-01-16  9:31           ` Jarkko Sakkinen
2021-01-16  9:50             ` Jarkko Sakkinen

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