lkml.org 
[lkml]   [2021]   [Dec]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 13/25] x86/sgx: Support adding of pages to initialized enclave
From
Date
On 12/1/21 11:23 AM, Reinette Chatre wrote:
> +static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
> + struct sgx_encl *encl, unsigned long addr)
> +{
> + struct sgx_pageinfo pginfo = {0};
> + struct sgx_encl_page *encl_page;
> + struct sgx_epc_page *epc_page;
> + struct sgx_va_page *va_page;
> + unsigned long phys_addr;
> + unsigned long prot;
> + vm_fault_t vmret;
> + int ret;
> +
> + if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
> + return VM_FAULT_SIGBUS;
> +
> + encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL);
> + if (!encl_page)
> + return VM_FAULT_OOM;
> +
> + encl_page->desc = addr;
> + encl_page->encl = encl;
> +
> + /*
> + * Adding a regular page that is architecturally allowed to only
> + * be created with RW permissions.
> + * TBD: Interface with user space policy to support max permissions
> + * of RWX.
> + */
> + prot = PROT_READ | PROT_WRITE;
> + encl_page->vm_run_prot_bits = calc_vm_prot_bits(prot, 0);
> + encl_page->vm_max_prot_bits = encl_page->vm_run_prot_bits;
> +
> + epc_page = sgx_alloc_epc_page(encl_page, true);
> + if (IS_ERR(epc_page)) {
> + kfree(encl_page);
> + return VM_FAULT_SIGBUS;
> + }
> +
> + va_page = sgx_encl_grow(encl);
> + if (IS_ERR(va_page)) {
> + ret = PTR_ERR(va_page);
> + goto err_out_free;
> + }
> +
> + mutex_lock(&encl->lock);
> +
> + /*
> + * Copy comment from sgx_encl_add_page() to maintain guidance in
> + * this similar flow:
> + * Adding to encl->va_pages must be done under encl->lock. Ditto for
> + * deleting (via sgx_encl_shrink()) in the error path.
> + */
> + if (va_page)
> + list_add(&va_page->list, &encl->va_pages);
> +
> + ret = xa_insert(&encl->page_array, PFN_DOWN(encl_page->desc),
> + encl_page, GFP_KERNEL);
> + /*
> + * If ret == -EBUSY then page was created in another flow while
> + * running without encl->lock
> + */
> + if (ret)
> + goto err_out_unlock;
> +
> + pginfo.secs = (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page);
> + pginfo.addr = encl_page->desc & PAGE_MASK;
> + pginfo.metadata = 0;
> +
> + ret = __eaug(&pginfo, sgx_get_epc_virt_addr(epc_page));
> + if (ret)
> + goto err_out;
> +
> + encl_page->encl = encl;
> + encl_page->epc_page = epc_page;
> + encl_page->type = SGX_PAGE_TYPE_REG;
> + encl->secs_child_cnt++;
> +
> + sgx_mark_page_reclaimable(encl_page->epc_page);
> +
> + phys_addr = sgx_get_epc_phys_addr(epc_page);
> + /*
> + * Do not undo everything when creating PTE entry fails - next #PF
> + * would find page ready for a PTE.
> + * PAGE_SHARED because protection is forced to be RW above and COW
> + * is not supported.
> + */
> + vmret = vmf_insert_pfn_prot(vma, addr, PFN_DOWN(phys_addr),
> + PAGE_SHARED);
> + if (vmret != VM_FAULT_NOPAGE) {
> + mutex_unlock(&encl->lock);
> + return VM_FAULT_SIGBUS;
> + }
> + mutex_unlock(&encl->lock);
> + return VM_FAULT_NOPAGE;
> +
> +err_out:
> + xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc));
> +
> +err_out_unlock:
> + sgx_encl_shrink(encl, va_page);
> + mutex_unlock(&encl->lock);
> +
> +err_out_free:
> + sgx_encl_free_epc_page(epc_page);
> + kfree(encl_page);
> +
> + return VM_FAULT_SIGBUS;
> +}

There seems to be very little code sharing between this and the existing
page addition. Are we confident that no refactoring here is in order?

\
 
 \ /
  Last update: 2021-12-03 01:40    [W:0.285 / U:1.864 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site