From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jethro Beekman <jethro@fortanix.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"x86@kernel.org" <x86@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Josh Triplett <josh@joshtriplett.org>,
Haitao Huang <haitao.huang@linux.intel.com>,
"Dr . Greg Wettstein" <greg@enjellic.com>
Subject: Re: x86/sgx: uapi change proposal
Date: Wed, 19 Dec 2018 06:45:15 -0800 [thread overview]
Message-ID: <20181219144515.GA30909@linux.intel.com> (raw)
In-Reply-To: <613c6814-4e71-38e5-444a-545f0e286df8@fortanix.com>
On Wed, Dec 19, 2018 at 09:36:16AM +0000, Jethro Beekman wrote:
> On 2018-12-19 14:41, Jarkko Sakkinen wrote:
> >On Wed, Dec 19, 2018 at 08:41:12AM +0000, Jethro Beekman wrote:
> >>One weird thing is the departure from the normal mmap behavior that the
> >>memory mapping persists even if the original fd is closed. (See man mmap:
> >>"closing the file descriptor does not unmap the region.")
It won't (be a departure). mmap() on a file grabs a reference to the
file, i.e. each VMA keeps a reference to the file. Closing the original
enclave fd will only put its reference to the file/enclave, not destroy
it outright.
> >
> >The mmapped region and enclave would be completely disjoint to start
> >with. The enclave driver code would assume that an enclave VMA exists
> >when it maps enclave address space to a process.
> >
> >I.e. VMA would no longer reference to the enclave or vice versa but
> >you would still create an enclave VMA with mmap().
> >
> >This is IMHO very clear and well-defined semantics.
> >
> >>>struct sgx_enclave_add_page {
> >>> __u64 enclave_fd;
> >>> __u64 src;
> >>> __u64 secinfo;
> >>> __u16 mrmask;
> >>>} __attribute__((__packed__));
> >>
> >>Wouldn't you just pass enclave_fd as the ioctl fd parameter?
> >
> >I'm still planning to keep the API in the device fd and use enclave_fd
> >as handle to the enclave address space. I don't see any obvious reason
> >to change that behavior.
> >
> >And if we ever add any "global" ioctls, then we would have to define
> >APIs to both fd's, which would become a mess.
> >
> >>How to specify the address of the page that is being added?
> >
> >Yes, that is correct and my bad to remove it (just quickly drafted what
> >I had in mind).
>
> So your plan is that to call EADD, userspace has to pass the device fd AND
> the enclave fd AND the enclave address? That seems a little superfluous.
I agree with Jethro, passing the enclave_fd as a param is obnoxious.
And it means the user needs to open /dev/sgx to do anything with an
enclave fd, e.g. the enclave fd might be passed to a builder thread,
it shouldn't also need the device fd.
E.g.:
sgx_fd = open("/dev/sgx", O_RDWR);
BUG_ON(sgx_fd < 0);
enclave_fd = ioctl(sgx_fd, SGX_ENCLAVE_CREATE, &ecreate);
BUG_ON(enclave_fd < 0);
ret = ioctl(enclave_fd, SGX_ENCLAVE_ADD_PAGE, &eadd);
BUG_ON(ret);
...
ret = ioctl(enclave_fd, SGX_ENCLAVE_INIT, &einit);
BUG_ON(ret);
...
close(enclave_fd);
close(sgx_fd);
Take a look at virt/kvm/kvm_main.c to see how KVM manages anon inodes
and ioctls for VMs and vCPUs.
next prev parent reply other threads:[~2018-12-19 14:45 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 21:57 [RFC PATCH v5 0/5] x86: Add vDSO exception fixup for SGX Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 1/5] x86/vdso: Add support for exception fixup in vDSO functions Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 2/5] x86/fault: Add helper function to sanitize error code Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 3/5] x86/fault: Attempt to fixup unhandled #PF on ENCLU before signaling Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 4/5] x86/traps: Attempt to fixup exceptions in vDSO " Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 5/5] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions Sean Christopherson
2018-12-19 9:21 ` Jarkko Sakkinen
2018-12-18 4:18 ` [RFC PATCH v5 0/5] x86: Add vDSO exception fixup for SGX Jarkko Sakkinen
2018-12-18 15:08 ` Sean Christopherson
2018-12-19 4:43 ` Jarkko Sakkinen
2018-12-19 5:03 ` Jarkko Sakkinen
2018-12-19 7:58 ` x86/sgx: uapi change proposal Jarkko Sakkinen
2018-12-19 8:41 ` Jethro Beekman
2018-12-19 9:11 ` Jarkko Sakkinen
2018-12-19 9:36 ` Jethro Beekman
2018-12-19 10:43 ` Jarkko Sakkinen
2018-12-19 14:45 ` Sean Christopherson [this message]
2018-12-20 2:58 ` Andy Lutomirski
2018-12-20 10:32 ` Jarkko Sakkinen
2018-12-20 13:12 ` Jarkko Sakkinen
2018-12-20 13:19 ` Jarkko Sakkinen
2018-12-22 8:16 ` Jarkko Sakkinen
[not found] ` <20181222082502.GA13275@linux.intel.com>
2018-12-23 12:52 ` Jarkko Sakkinen
2018-12-23 20:42 ` Andy Lutomirski
2018-12-24 11:52 ` Jarkko Sakkinen
2019-01-02 20:47 ` Sean Christopherson
2019-01-03 15:02 ` Jarkko Sakkinen
[not found] ` <20190103162634.GA8610@linux.intel.com>
2019-01-09 14:45 ` Jarkko Sakkinen
2018-12-21 16:28 ` Sean Christopherson
2018-12-21 17:12 ` Andy Lutomirski
2018-12-21 18:24 ` Sean Christopherson
2018-12-21 23:41 ` Jarkko Sakkinen
2018-12-23 20:41 ` Andy Lutomirski
2018-12-24 12:01 ` Jarkko Sakkinen
2018-12-21 23:37 ` Jarkko Sakkinen
2018-12-22 6:32 ` Jarkko Sakkinen
2019-01-08 19:27 ` Huang, Kai
2019-01-08 22:09 ` Sean Christopherson
2019-01-08 22:54 ` Andy Lutomirski
2019-01-09 16:31 ` Sean Christopherson
2019-01-10 21:34 ` Andy Lutomirski
2019-01-10 22:22 ` Huang, Kai
2019-01-10 23:54 ` Sean Christopherson
2019-01-11 0:30 ` Andy Lutomirski
2019-01-11 1:32 ` Sean Christopherson
2019-01-11 12:58 ` Jarkko Sakkinen
2019-01-11 13:00 ` Jarkko Sakkinen
2019-01-11 23:19 ` Sean Christopherson
2019-01-18 14:37 ` Jarkko Sakkinen
2019-01-10 17:45 ` Jarkko Sakkinen
2019-01-10 21:36 ` Andy Lutomirski
2019-01-11 16:07 ` Jarkko Sakkinen
2019-01-09 5:24 ` Huang, Kai
2019-01-09 17:16 ` Sean Christopherson
2019-01-10 0:21 ` Huang, Kai
2019-01-10 0:40 ` Sean Christopherson
2019-01-10 17:43 ` Jarkko Sakkinen
2018-12-20 10:30 ` Jarkko Sakkinen
2018-12-19 14:43 ` Dr. Greg
2018-12-20 10:34 ` Jarkko Sakkinen
2018-12-20 22:06 ` Dr. Greg
2018-12-21 13:48 ` Jarkko Sakkinen
2018-12-20 12:08 ` Arnd Bergmann
2018-12-20 12:49 ` Jarkko Sakkinen
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