Messages in this thread | | | Date | Thu, 26 May 2022 12:37:10 -0300 | From | Wander Lairson Costa <> | Subject | Re: [PATCH v7 5/5] x86/tdx: Add Quote generation support |
| |
On Mon, May 23, 2022 at 09:05:17PM -0700, Kuppuswamy Sathyanarayanan wrote: > + > +/* Used for buffer allocation in GetQuote request */ > +struct quote_buf { > + /* vmapped address of kernel buffer (size is page aligned) */ > + void *vmaddr; > + /* Number of pages */ > + int count; > +}; > + > +/* List entry of quote_list */ > +struct quote_entry { > + /* Flag to check validity of the GetQuote request */ > + bool valid; > + /* Kernel buffer to share data with VMM */ > + struct quote_buf *buf;
Instead of a pointer, we can embed the quote_buf object directly into the quote_entry. alloc_quote_buf would receive a pointer to quote_buf, and would only allocate vmaddr (may we should change the names from alloc/free to init/deinit). This way we can save one memory allocation and have a simpler code. Not to mention is one less pointer to track its lifetime.
> + /* Completion object to track completion of GetQuote request */ > + struct completion compl; > + struct list_head list; > +}; > > static struct miscdevice miscdev; > > +/* > + * To support parallel GetQuote requests, use the list > + * to track active GetQuote requests. > + */ > +static LIST_HEAD(quote_list); > + > +/* Lock to protect quote_list */ > +static DEFINE_MUTEX(quote_lock); > + > +/* > + * Workqueue to handle Quote data after Quote generation > + * notification from VMM. > + */ > +struct workqueue_struct *quote_wq; > +struct work_struct quote_work; > + > static long tdx_get_report(void __user *argp) > { > void *reportdata = NULL, *tdreport = NULL; > @@ -71,6 +111,270 @@ static long tdx_get_report(void __user *argp) > return ret; > } > > +/* tdx_get_quote_hypercall() - Request to get TD Quote using TDREPORT */ > +static long tdx_get_quote_hypercall(struct quote_buf *buf) > +{ > + struct tdx_hypercall_args args = {0}; > + > + args.r10 = TDX_HYPERCALL_STANDARD; > + args.r11 = TDVMCALL_GET_QUOTE; > + args.r12 = cc_mkdec(page_to_phys(vmalloc_to_page(buf->vmaddr))); > + args.r13 = buf->count * PAGE_SIZE; > + > + /* > + * Pass the physical address of TDREPORT to the VMM and > + * trigger the Quote generation. It is not a blocking > + * call, hence completion of this request will be notified to > + * the TD guest via a callback interrupt. More info about ABI > + * can be found in TDX Guest-Host-Communication Interface > + * (GHCI), sec titled "TDG.VP.VMCALL<GetQuote>". > + */ > + return __tdx_hypercall(&args, 0); > +} > + > +/* > + * alloc_quote_buf() - Used to allocate a shared buffer of > + * given size. > + * > + * Size is page aligned and the allocated memory is decrypted > + * to allow VMM to access it. Uses VMAP to create a virtual > + * mapping, which is further used to create a shared mapping > + * for the buffer without affecting the direct map. > + */ > +static struct quote_buf *alloc_quote_buf(u64 req_size) > +{ > + int size = PAGE_ALIGN(req_size); > + void *addr = NULL, *vmaddr = NULL; > + int count = size >> PAGE_SHIFT; > + struct page **pages = NULL; > + struct quote_buf *buf; > + int i; > + > + buf = kmalloc(sizeof(*buf), GFP_KERNEL); > + if (!buf) > + return NULL; > + > + addr = alloc_pages_exact(size, GFP_KERNEL); > + if (!addr) > + goto alloc_failed; > + > + /* Allocate mem for array of page ptrs */ > + pages = kcalloc(count, sizeof(*pages), GFP_KERNEL); > + if (!pages) > + goto alloc_failed; > + > + for (i = 0; i < count; i++) > + pages[i] = virt_to_page(addr + i * PAGE_SIZE); > + > + /* > + * Use VMAP to create a virtual mapping, which is used > + * to create shared mapping without affecting the > + * direct map. Use VM_MAP_PUT_PAGES to allow vmap() > + * responsible for freeing the pages when using vfree(). > + */ > + vmaddr = vmap(pages, count, VM_MAP_PUT_PAGES, PAGE_KERNEL); > + if (!vmaddr) > + goto alloc_failed; > + > + /* Use noalias variant to not affect the direct mapping */ > + if (set_memory_decrypted_noalias((unsigned long)vmaddr, count)) > + goto alloc_failed; > + > + buf->vmaddr = vmaddr; > + buf->count = count; > + > + return buf; > + > +alloc_failed: > + if (!vmaddr) { > + kfree(pages); > + if (addr) > + free_pages_exact(addr, size); > + } > + vfree(vmaddr); > + kfree(buf); > + return NULL; > +} > + > +/* Remove the shared mapping and free the buffer */ > +static void free_quote_buf(struct quote_buf *buf) > +{ > + if (!buf) > + return; > + > + /* Mark pages private */ > + if (set_memory_encrypted_noalias((unsigned long)buf->vmaddr, > + buf->count)) { > + pr_warn("Failed to encrypt %d pages at %p", buf->count, > + buf->vmaddr); > + return; > + } > + > + vfree(buf->vmaddr); > + kfree(buf); > +} > + > +static struct quote_entry *alloc_quote_entry(u64 buf_len) > +{ > + struct quote_entry *entry = NULL; > + > + entry = kmalloc(sizeof(*entry), GFP_KERNEL); > + if (!entry) > + return NULL; > + > + /* Allocate buffer for quote request */ > + entry->buf = alloc_quote_buf(buf_len); > + if (!entry->buf) { > + kfree(entry); > + return NULL; > + } > + > + init_completion(&entry->compl); > + entry->valid = true; > + > + return entry; > +} > + > +static void free_quote_entry(struct quote_entry *entry) > +{ > + free_quote_buf(entry->buf); > + kfree(entry); > +} > +
| |