Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753043AbdLDQfY (ORCPT ); Mon, 4 Dec 2017 11:35:24 -0500 Received: from mga02.intel.com ([134.134.136.20]:46236 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752416AbdLDQfV (ORCPT ); Mon, 4 Dec 2017 11:35:21 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.45,359,1508828400"; d="scan'208";a="9395361" Date: Mon, 4 Dec 2017 19:34:45 +0300 From: "Kirill A. Shutemov" To: Tom Lendacky Cc: "Kirill A. Shutemov" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Borislav Petkov , Brijesh Singh , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/mm: Rewrite sme_populate_pgd() in a more sensible way Message-ID: <20171204163445.qt5dqcrrkilnhowz@black.fi.intel.com> References: <20171204112323.47019-1-kirill.shutemov@linux.intel.com> <20171204145755.6xu2w6a6og56rq5v@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170714-126-deb55f (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5141 Lines: 163 On Mon, Dec 04, 2017 at 04:00:26PM +0000, Tom Lendacky wrote: > On 12/4/2017 8:57 AM, Kirill A. Shutemov wrote: > > On Mon, Dec 04, 2017 at 08:19:11AM -0600, Tom Lendacky wrote: > > > On 12/4/2017 5:23 AM, Kirill A. Shutemov wrote: > > > > sme_populate_pgd() open-codes a lot of things that are not needed to be > > > > open-coded. > > > > > > > > Let's rewrite it in a more stream-lined way. > > > > > > > > This would also buy us boot-time switching between support between > > > > paging modes, when rest of the pieces will be upstream. > > > > > > Hi Kirill, > > > > > > Unfortunately, some of these can't be changed. The use of p4d_offset(), > > > pud_offset(), etc., use non-identity mapped virtual addresses which cause > > > failures at this point of the boot process. > > > > Wat? Virtual address is virtual address. p?d_offset() doesn't care about > > what mapping you're using. > > Yes it does. For example, pmd_offset() issues a pud_page_addr() call, > which does a __va() returning a non-identity mapped address (0xffff88...). > Only identity mapped virtual addresses have been setup at this point, so > the use of that virtual address panics the kernel. Stupid me. You are right. What about something like this: diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index d9a9e9fc75dd..65e0d68f863f 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -12,6 +12,23 @@ #define DISABLE_BRANCH_PROFILING +/* + * Since we're dealing with identity mappings, physical and virtual + * addresses are the same, so override these defines which are ultimately + * used by the headers in misc.h. + */ +#define __pa(x) ((unsigned long)(x)) +#define __va(x) ((void *)((unsigned long)(x))) + +/* + * Special hack: we have to be careful, because no indirections are + * allowed here, and paravirt_ops is a kind of one. As it will only run in + * baremetal anyway, we just keep it from happening. (This list needs to + * be extended when new paravirt and debugging variants are added.) + */ +#undef CONFIG_PARAVIRT +#undef CONFIG_PARAVIRT_SPINLOCKS + #include #include #include @@ -489,73 +506,42 @@ static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start, static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area, unsigned long vaddr, pmdval_t pmd_val) { - pgd_t *pgd_p; - p4d_t *p4d_p; - pud_t *pud_p; - pmd_t *pmd_p; - - pgd_p = pgd_base + pgd_index(vaddr); - if (native_pgd_val(*pgd_p)) { - if (IS_ENABLED(CONFIG_X86_5LEVEL)) - p4d_p = (p4d_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK); - else - pud_p = (pud_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK); - } else { - pgd_t pgd; - - if (IS_ENABLED(CONFIG_X86_5LEVEL)) { - p4d_p = pgtable_area; - memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D); - pgtable_area += sizeof(*p4d_p) * PTRS_PER_P4D; - - pgd = native_make_pgd((pgdval_t)p4d_p + PGD_FLAGS); - } else { - pud_p = pgtable_area; - memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD); - pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD; - - pgd = native_make_pgd((pgdval_t)pud_p + PGD_FLAGS); - } - native_set_pgd(pgd_p, pgd); + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + pgd = pgd_base + pgd_index(vaddr); + if (pgd_none(*pgd)) { + p4d = pgtable_area; + memset(p4d, 0, sizeof(*p4d) * PTRS_PER_P4D); + pgtable_area += sizeof(*p4d) * PTRS_PER_P4D; + set_pgd(pgd, __pgd(PGD_FLAGS | __pa(p4d))); } - if (IS_ENABLED(CONFIG_X86_5LEVEL)) { - p4d_p += p4d_index(vaddr); - if (native_p4d_val(*p4d_p)) { - pud_p = (pud_t *)(native_p4d_val(*p4d_p) & ~PTE_FLAGS_MASK); - } else { - p4d_t p4d; - - pud_p = pgtable_area; - memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD); - pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD; - - p4d = native_make_p4d((pudval_t)pud_p + P4D_FLAGS); - native_set_p4d(p4d_p, p4d); - } + p4d = p4d_offset(pgd, vaddr); + if (p4d_none(*p4d)) { + pud = pgtable_area; + memset(pud, 0, sizeof(*pud) * PTRS_PER_PUD); + pgtable_area += sizeof(*pud) * PTRS_PER_PUD; + set_p4d(p4d, __p4d(P4D_FLAGS | __pa(pud))); } - pud_p += pud_index(vaddr); - if (native_pud_val(*pud_p)) { - if (native_pud_val(*pud_p) & _PAGE_PSE) - goto out; - - pmd_p = (pmd_t *)(native_pud_val(*pud_p) & ~PTE_FLAGS_MASK); - } else { - pud_t pud; - - pmd_p = pgtable_area; - memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD); - pgtable_area += sizeof(*pmd_p) * PTRS_PER_PMD; - - pud = native_make_pud((pmdval_t)pmd_p + PUD_FLAGS); - native_set_pud(pud_p, pud); + pud = pud_offset(p4d, vaddr); + if (pud_none(*pud)) { + pmd = pgtable_area; + memset(pmd, 0, sizeof(*pmd) * PTRS_PER_PMD); + pgtable_area += sizeof(*pmd) * PTRS_PER_PMD; + set_pud(pud, __pud(PUD_FLAGS | __pa(pmd))); } + if (pud_large(*pud)) + goto out; - pmd_p += pmd_index(vaddr); - if (!native_pmd_val(*pmd_p) || !(native_pmd_val(*pmd_p) & _PAGE_PSE)) - native_set_pmd(pmd_p, native_make_pmd(pmd_val)); + pmd = pmd_offset(pud, vaddr); + if (pmd_large(*pmd)) + goto out; + set_pmd(pmd, __pmd(pmd_val)); out: return pgtable_area; } -- Kirill A. Shutemov