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Shutemov" To: Peter Zijlstra Cc: "Kirill A. Shutemov" , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Andy Lutomirski , David Howells , Kees Cook , Dave Hansen , Kai Huang , Jacob Pan , Alison Schofield , linux-mm@kvack.org, kvm@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH, RFC 18/62] x86/mm: Implement syncing per-KeyID direct mappings Message-ID: <20190617144328.oqwx5rb5yfm2ziws@box> References: <20190508144422.13171-1-kirill.shutemov@linux.intel.com> <20190508144422.13171-19-kirill.shutemov@linux.intel.com> <20190614095131.GY3436@hirez.programming.kicks-ass.net> <20190614224309.t4ce7lpx577qh2gu@box> <20190617092755.GA3419@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190617092755.GA3419@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20180716 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Jun 17, 2019 at 11:27:55AM +0200, Peter Zijlstra wrote: > On Sat, Jun 15, 2019 at 01:43:09AM +0300, Kirill A. Shutemov wrote: > > On Fri, Jun 14, 2019 at 11:51:32AM +0200, Peter Zijlstra wrote: > > > On Wed, May 08, 2019 at 05:43:38PM +0300, Kirill A. Shutemov wrote: > > > > For MKTME we use per-KeyID direct mappings. This allows kernel to have > > > > access to encrypted memory. > > > > > > > > sync_direct_mapping() sync per-KeyID direct mappings with a canonical > > > > one -- KeyID-0. > > > > > > > > The function tracks changes in the canonical mapping: > > > > - creating or removing chunks of the translation tree; > > > > - changes in mapping flags (i.e. protection bits); > > > > - splitting huge page mapping into a page table; > > > > - replacing page table with a huge page mapping; > > > > > > > > The function need to be called on every change to the direct mapping: > > > > hotplug, hotremove, changes in permissions bits, etc. > > > > > > And yet I don't see anything in pageattr.c. > > > > You're right. I've hooked up the sync in the wrong place. > > > > > > Also, this seems like an expensive scheme; if you know where the changes > > > where, a more fine-grained update would be faster. > > > > Do we have any hot enough pageattr users that makes it crucial? > > > > I'll look into this anyway. > > The graphics people would be the most agressive users of this I'd think. > They're the ones that yelled when I broke it last ;-) I think something like this should do (I'll fold it in after testing): diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h index 6c973cb1e64c..b30386d84281 100644 --- a/arch/x86/include/asm/mktme.h +++ b/arch/x86/include/asm/mktme.h @@ -68,7 +68,7 @@ static inline void arch_free_page(struct page *page, int order) free_encrypted_page(page, order); } -int sync_direct_mapping(void); +int sync_direct_mapping(unsigned long start, unsigned long end); int mktme_get_alg(int keyid); @@ -86,7 +86,7 @@ static inline bool mktme_enabled(void) static inline void mktme_disable(void) {} -static inline int sync_direct_mapping(void) +static inline int sync_direct_mapping(unsigned long start, unsigned long end) { return 0; } diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index f50a38d86cc4..f8123aeb24a6 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -761,7 +761,7 @@ __kernel_physical_mapping_init(unsigned long paddr_start, pgd_changed = true; } - ret = sync_direct_mapping(); + ret = sync_direct_mapping(vaddr_start, vaddr_end); WARN_ON(ret); if (pgd_changed) @@ -1209,7 +1209,7 @@ kernel_physical_mapping_remove(unsigned long start, unsigned long end) end = (unsigned long)__va(end); remove_pagetable(start, end, true, NULL); - ret = sync_direct_mapping(); + ret = sync_direct_mapping(start, end); WARN_ON(ret); } @@ -1315,7 +1315,6 @@ void mark_rodata_ro(void) unsigned long text_end = PFN_ALIGN(&__stop___ex_table); unsigned long rodata_end = PFN_ALIGN(&__end_rodata); unsigned long all_end; - int ret; printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n", (end - start) >> 10); @@ -1349,8 +1348,6 @@ void mark_rodata_ro(void) free_kernel_image_pages((void *)text_end, (void *)rodata_start); free_kernel_image_pages((void *)rodata_end, (void *)_sdata); - ret = sync_direct_mapping(); - WARN_ON(ret); debug_checkwx(); } diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c index 9d2bb534f2ba..c099e1da055b 100644 --- a/arch/x86/mm/mktme.c +++ b/arch/x86/mm/mktme.c @@ -76,7 +76,7 @@ static void init_page_mktme(void) { static_branch_enable(&mktme_enabled_key); - sync_direct_mapping(); + sync_direct_mapping(PAGE_OFFSET, PAGE_OFFSET + direct_mapping_size); } struct page_ext_operations page_mktme_ops = { @@ -596,15 +596,13 @@ static int sync_direct_mapping_p4d(unsigned long keyid, return ret; } -static int sync_direct_mapping_keyid(unsigned long keyid) +static int sync_direct_mapping_keyid(unsigned long keyid, + unsigned long addr, unsigned long end) { pgd_t *src_pgd, *dst_pgd; - unsigned long addr, end, next; + unsigned long next; int ret = 0; - addr = PAGE_OFFSET; - end = PAGE_OFFSET + direct_mapping_size; - dst_pgd = pgd_offset_k(addr + keyid * direct_mapping_size); src_pgd = pgd_offset_k(addr); @@ -643,7 +641,7 @@ static int sync_direct_mapping_keyid(unsigned long keyid) * * The function is nop until MKTME is enabled. */ -int sync_direct_mapping(void) +int sync_direct_mapping(unsigned long start, unsigned long end) { int i, ret = 0; @@ -651,7 +649,7 @@ int sync_direct_mapping(void) return 0; for (i = 1; !ret && i <= mktme_nr_keyids; i++) - ret = sync_direct_mapping_keyid(i); + ret = sync_direct_mapping_keyid(i, start, end); flush_tlb_all(); diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 6a9a77a403c9..eafbe0d8c44f 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -347,6 +347,28 @@ static void cpa_flush(struct cpa_data *data, int cache) BUG_ON(irqs_disabled() && !early_boot_irqs_disabled); + if (mktme_enabled()) { + unsigned long start, end; + + start = *cpa->vaddr; + end = *cpa->vaddr + cpa->numpages * PAGE_SIZE; + + /* Sync all direct mapping for an array */ + if (cpa->flags & CPA_ARRAY) { + start = PAGE_OFFSET; + end = PAGE_OFFSET + direct_mapping_size; + } + + /* + * Sync per-KeyID direct mappings with the canonical one + * (KeyID-0). + * + * sync_direct_mapping() does full TLB flush. + */ + sync_direct_mapping(start, end); + return; + } + if (cache && !static_cpu_has(X86_FEATURE_CLFLUSH)) { cpa_flush_all(cache); return; -- Kirill A. Shutemov