From patchwork Mon May 13 11:11:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Elias El Yandouzi X-Patchwork-Id: 13663339 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6C101C41513 for ; Mon, 13 May 2024 11:12:07 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.720812.1123792 (Exim 4.92) (envelope-from ) id 1s6Tb5-0005Hk-FU; Mon, 13 May 2024 11:11:59 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 720812.1123792; Mon, 13 May 2024 11:11:59 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1s6Tb5-0005HA-9E; Mon, 13 May 2024 11:11:59 +0000 Received: by outflank-mailman (input) for mailman id 720812; Mon, 13 May 2024 11:11:57 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1s6Tb3-00036L-Dw for xen-devel@lists.xenproject.org; Mon, 13 May 2024 11:11:57 +0000 Received: from smtp-fw-80006.amazon.com (smtp-fw-80006.amazon.com [99.78.197.217]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 9aeed16a-1119-11ef-b4bb-af5377834399; Mon, 13 May 2024 13:11:54 +0200 (CEST) Received: from pdx4-co-svc-p1-lb2-vlan3.amazon.com (HELO smtpout.prod.us-east-1.prod.farcaster.email.amazon.dev) ([10.25.36.214]) by smtp-border-fw-80006.pdx80.corp.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 May 2024 11:11:54 +0000 Received: from EX19MTAUEA001.ant.amazon.com [10.0.0.204:23012] by smtpin.naws.us-east-1.prod.farcaster.email.amazon.dev [10.0.82.155:2525] with esmtp (Farcaster) id db499768-4150-42be-b874-549dc3061146; Mon, 13 May 2024 11:11:53 +0000 (UTC) Received: from EX19D008UEA004.ant.amazon.com (10.252.134.191) by EX19MTAUEA001.ant.amazon.com (10.252.134.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Mon, 13 May 2024 11:11:52 +0000 Received: from EX19MTAUWB001.ant.amazon.com (10.250.64.248) by EX19D008UEA004.ant.amazon.com (10.252.134.191) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Mon, 13 May 2024 11:11:51 +0000 Received: from dev-dsk-eliasely-1a-fd74790f.eu-west-1.amazon.com (10.253.91.118) by mail-relay.amazon.com (10.250.64.254) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28 via Frontend Transport; Mon, 13 May 2024 11:11:50 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 9aeed16a-1119-11ef-b4bb-af5377834399 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1715598715; x=1747134715; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=roZUKjZFy3HRbWFvKqZPI52BDqwj8toyBUHm6ct47Gk=; b=NDcqzEFASk15KlCTwr8iJYGo6QEDkjCinUYtCaFMDf+yMI1+Tc8nJeYa ER9GvxjwQZajhjPbPHE/cQcRNEeGipMwPAAg+NUdKfrvrN7Gp470QCAYm zjYHWSLWDN+E3pv6c2e8dDSMzXDR9QLU+HJ4EbcAOvThN0uguXj9+JLKw g=; X-IronPort-AV: E=Sophos;i="6.08,158,1712620800"; d="scan'208";a="294662424" X-Farcaster-Flow-ID: db499768-4150-42be-b874-549dc3061146 From: Elias El Yandouzi To: CC: , , , Hongyan Xia , Julien Grall , Elias El Yandouzi Subject: [PATCH V3 13/19] x86/setup: Do not create valid mappings when directmap=no Date: Mon, 13 May 2024 11:11:11 +0000 Message-ID: <20240513111117.68828-14-eliasely@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240513111117.68828-1-eliasely@amazon.com> References: <20240513111117.68828-1-eliasely@amazon.com> MIME-Version: 1.0 From: Hongyan Xia Create empty mappings in the second e820 pass. Also, destroy existing direct map mappings created in the first pass. To make xenheap pages visible in guests, it is necessary to create empty L3 tables in the direct map even when directmap=no, since guest cr3s copy idle domain's L4 entries, which means they will share mappings in the direct map if we pre-populate idle domain's L4 entries and L3 tables. A helper is introduced for this. Also, after the direct map is actually gone, we need to stop updating the direct map in update_xen_mappings(). Signed-off-by: Hongyan Xia Signed-off-by: Julien Grall Signed-off-by: Elias El Yandouzi diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index f26c9799e4..919347d8c2 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -978,6 +978,57 @@ static struct domain *__init create_dom0(const module_t *image, /* How much of the directmap is prebuilt at compile time. */ #define PREBUILT_MAP_LIMIT (1 << L2_PAGETABLE_SHIFT) +/* + * This either populates a valid direct map, or allocates empty L3 tables and + * creates the L4 entries for virtual address between [start, end) in the + * direct map depending on has_directmap(); + * + * When directmap=no, we still need to populate empty L3 tables in the + * direct map region. The reason is that on-demand xenheap mappings are + * created in the idle domain's page table but must be seen by + * everyone. Since all domains share the direct map L4 entries, they + * will share xenheap mappings if we pre-populate the L4 entries and L3 + * tables in the direct map region for all RAM. We also rely on the fact + * that L3 tables are never freed. + */ +static void __init populate_directmap(uint64_t pstart, uint64_t pend, + unsigned int flags) +{ + unsigned long vstart = (unsigned long)__va(pstart); + unsigned long vend = (unsigned long)__va(pend); + + if ( pstart >= pend ) + return; + + BUG_ON(vstart < DIRECTMAP_VIRT_START); + BUG_ON(vend > DIRECTMAP_VIRT_END); + + if ( has_directmap() ) + /* Populate valid direct map. */ + BUG_ON(map_pages_to_xen(vstart, maddr_to_mfn(pstart), + PFN_DOWN(pend - pstart), flags)); + else + { + /* Create empty L3 tables. */ + unsigned long vaddr = vstart & ~((1UL << L4_PAGETABLE_SHIFT) - 1); + + for ( ; vaddr < vend; vaddr += (1UL << L4_PAGETABLE_SHIFT) ) + { + l4_pgentry_t *pl4e = &idle_pg_table[l4_table_offset(vaddr)]; + + if ( !(l4e_get_flags(*pl4e) & _PAGE_PRESENT) ) + { + mfn_t mfn = alloc_boot_pages(1, 1); + void *v = map_domain_page(mfn); + + clear_page(v); + UNMAP_DOMAIN_PAGE(v); + l4e_write(pl4e, l4e_from_mfn(mfn, __PAGE_HYPERVISOR)); + } + } + } +} + void asmlinkage __init noreturn __start_xen(unsigned long mbi_p) { const char *memmap_type = NULL, *loader, *cmdline = ""; @@ -1601,8 +1652,17 @@ void asmlinkage __init noreturn __start_xen(unsigned long mbi_p) map_e = min_t(uint64_t, e, ARRAY_SIZE(l2_directmap) << L2_PAGETABLE_SHIFT); - /* Pass mapped memory to allocator /before/ creating new mappings. */ + /* + * Pass mapped memory to allocator /before/ creating new mappings. + * The direct map for the bottom 4GiB has been populated in the first + * e820 pass. In the second pass, we make sure those existing mappings + * are destroyed when directmap=no. + */ init_boot_pages(s, min(map_s, e)); + if ( !has_directmap() ) + destroy_xen_mappings((unsigned long)__va(s), + (unsigned long)__va(min(map_s, e))); + s = map_s; if ( s < map_e ) { @@ -1610,6 +1670,9 @@ void asmlinkage __init noreturn __start_xen(unsigned long mbi_p) map_s = (s + mask) & ~mask; map_e &= ~mask; init_boot_pages(map_s, map_e); + if ( !has_directmap() ) + destroy_xen_mappings((unsigned long)__va(map_s), + (unsigned long)__va(map_e)); } if ( map_s > map_e ) @@ -1623,8 +1686,7 @@ void asmlinkage __init noreturn __start_xen(unsigned long mbi_p) if ( map_e < end ) { - map_pages_to_xen((unsigned long)__va(map_e), maddr_to_mfn(map_e), - PFN_DOWN(end - map_e), PAGE_HYPERVISOR); + populate_directmap(map_e, end, PAGE_HYPERVISOR); init_boot_pages(map_e, end); map_e = end; } @@ -1633,13 +1695,11 @@ void asmlinkage __init noreturn __start_xen(unsigned long mbi_p) { /* This range must not be passed to the boot allocator and * must also not be mapped with _PAGE_GLOBAL. */ - map_pages_to_xen((unsigned long)__va(map_e), maddr_to_mfn(map_e), - PFN_DOWN(e - map_e), __PAGE_HYPERVISOR_RW); + populate_directmap(map_e, e, __PAGE_HYPERVISOR_RW); } if ( s < map_s ) { - map_pages_to_xen((unsigned long)__va(s), maddr_to_mfn(s), - PFN_DOWN(map_s - s), PAGE_HYPERVISOR); + populate_directmap(s, map_s, PAGE_HYPERVISOR); init_boot_pages(s, map_s); } }