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    SubjectRe: [RFC PATCH 3/9] x86/sgx: Allow userspace to add multiple pages in single ioctl()
    On Sun, Jun 02, 2019 at 11:26:09PM -0700, Xing, Cedric wrote:
    > > From: Christopherson, Sean J
    > > Sent: Friday, May 31, 2019 4:32 PM
    > >
    > > +/**
    > > + * sgx_ioc_enclave_add_pages - handler for %SGX_IOC_ENCLAVE_ADD_PAGES
    > > + *
    > > + * @filep: open file to /dev/sgx
    > > + * @cmd: the command value
    > > + * @arg: pointer to an &sgx_enclave_add_page instance
    > > + *
    > > + * Add a range of pages to an uninitialized enclave (EADD), and
    > > +optionally
    > > + * extend the enclave's measurement with the contents of the page (EEXTEND).
    > > + * The range of pages must be virtually contiguous. The SECINFO and
    > > + * measurement maskare applied to all pages, i.e. pages with different
    > > + * properties must be added in separate calls.
    > > + *
    > > + * EADD and EEXTEND are done asynchronously via worker threads. A
    > > +successful
    > > + * sgx_ioc_enclave_add_page() only indicates the pages have been added
    > > +to the
    > > + * work queue, it does not guarantee adding the pages to the enclave
    > > +will
    > > + * succeed.
    > > + *
    > > + * Return:
    > > + * 0 on success,
    > > + * -errno otherwise
    > > + */
    > > +static long sgx_ioc_enclave_add_pages(struct file *filep, unsigned int cmd,
    > > + unsigned long arg)
    > > +{
    > > + struct sgx_enclave_add_pages *addp = (void *)arg;
    > > + struct sgx_encl *encl = filep->private_data;
    > > + struct sgx_secinfo secinfo;
    > > + unsigned int i;
    > > + int ret;
    > > +
    > > + if (copy_from_user(&secinfo, (void __user *)addp->secinfo,
    > > + sizeof(secinfo)))
    > > + return -EFAULT;
    > > +
    > > + for (i = 0, ret = 0; i < addp->nr_pages && !ret; i++) {
    > > + if (signal_pending(current))
    > > + return -ERESTARTSYS;
    >
    > If interrupted, how would user mode code know how many pages have been EADD'ed?

    Hmm, updating nr_pages would be fairly simple and shouldn't confuse
    userspace, e.g. as opposed to overloading the return value.

    > > +
    > > + if (need_resched())
    > > + cond_resched();
    > > +
    > > + ret = sgx_encl_add_page(encl, addp->addr + i*PAGE_SIZE,
    > > + addp->src + i*PAGE_SIZE,
    > > + &secinfo, addp->mrmask);
    > > + }
    > > return ret;
    > > }
    > >
    > > @@ -823,8 +845,8 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
    > > case SGX_IOC_ENCLAVE_CREATE:
    > > handler = sgx_ioc_enclave_create;
    > > break;
    > > - case SGX_IOC_ENCLAVE_ADD_PAGE:
    > > - handler = sgx_ioc_enclave_add_page;
    > > + case SGX_IOC_ENCLAVE_ADD_PAGES:
    > > + handler = sgx_ioc_enclave_add_pages;
    > > break;
    > > case SGX_IOC_ENCLAVE_INIT:
    > > handler = sgx_ioc_enclave_init;
    > > --
    > > 2.21.0
    >

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