From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E05B7125A3 for ; Thu, 5 Oct 2023 13:17:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="G+OlSlHt" Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696511823; x=1728047823; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=ja5J3yNUmltgYZsQ6ex9qPK0e1eU53KBqHupwbwonDY=; b=G+OlSlHtnBZQRgYT2liv48z7pPRvqYmOi6BrCcVfoLsUEtwTexfZW+b7 x2s2Yo/+CUSlGaSoZvnRJaUsuaGBaV2JS8NX2976PzscOT/3E87NyV4pT /gS0ztwd9Qpf37q1WfgCnUjQJTqCpsrFK2iXdIhC5jJaj9AYxyCPhxZC8 VyhBeUOTZKnRziScdw/6KWXnt1g+XySXbUnUbEkiHn/92bmINNrRNXxDA HkQ/NZTQJvZJd7SEQJbvf0gCLxueVR1KtDtRLdC8gGh99V5YBOKJV6y9R in3nHiCXpbGt9cGeTp6Az3/ABlg2TISZBjwuwb6UtotF27tN/wekhkAfZ Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10854"; a="382357575" X-IronPort-AV: E=Sophos;i="6.03,203,1694761200"; d="scan'208";a="382357575" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2023 06:14:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10854"; a="817564322" X-IronPort-AV: E=Sophos;i="6.03,203,1694761200"; d="scan'208";a="817564322" Received: from skwasnia-mobl.ger.corp.intel.com (HELO box.shutemov.name) ([10.251.222.71]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2023 06:14:23 -0700 Received: by box.shutemov.name (Postfix, from userid 1000) id 6748410A153; Thu, 5 Oct 2023 16:14:14 +0300 (+03) From: "Kirill A. Shutemov" To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "Rafael J. Wysocki" , Peter Zijlstra , Adrian Hunter , Kuppuswamy Sathyanarayanan , Elena Reshetova , Jun Nakajima , Rick Edgecombe , Tom Lendacky , kexec@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCH 09/13] x86/tdx: Account shared memory Date: Thu, 5 Oct 2023 16:13:58 +0300 Message-ID: <20231005131402.14611-10-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231005131402.14611-1-kirill.shutemov@linux.intel.com> References: <20231005131402.14611-1-kirill.shutemov@linux.intel.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The kernel will convert all shared memory back to private during kexec. The direct mapping page tables will provide information on which memory is shared. It is extremely important to convert all shared memory. If a page is missed, it will cause the target kernel to crash when it accesses it. Keep track of the number of shared pages. This will allow for cross-checking against the shared information in the direct mapping and reporting if the shared bit is lost. Include a debugfs interface that allows for the check to be performed at any point. Signed-off-by: Kirill A. Shutemov --- arch/x86/coco/tdx/tdx.c | 67 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 46022283d955..56e152126f20 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -5,6 +5,7 @@ #define pr_fmt(fmt) "tdx: " fmt #include +#include #include #include #include @@ -37,6 +38,13 @@ #define TDREPORT_SUBTYPE_0 0 +static atomic_long_t nr_shared; + +static inline bool pte_decrypted(pte_t pte) +{ + return cc_mkdec(pte_val(pte)) == pte_val(pte); +} + /* Called from __tdx_hypercall() for unrecoverable failure */ noinstr void __noreturn __tdx_hypercall_failed(void) { @@ -799,6 +807,11 @@ static int tdx_enc_status_change_finish(unsigned long vaddr, int numpages, if (!enc && !tdx_enc_status_changed(vaddr, numpages, enc)) return -EIO; + if (enc) + atomic_long_sub(numpages, &nr_shared); + else + atomic_long_add(numpages, &nr_shared); + return 0; } @@ -871,3 +884,57 @@ void __init tdx_early_init(void) pr_info("Guest detected\n"); } + +#ifdef CONFIG_DEBUG_FS +static int tdx_shared_memory_show(struct seq_file *m, void *p) +{ + unsigned long addr, end; + unsigned long found = 0; + + addr = PAGE_OFFSET; + end = PAGE_OFFSET + get_max_mapped(); + + while (addr < end) { + unsigned long size; + unsigned int level; + pte_t *pte; + + pte = lookup_address(addr, &level); + size = page_level_size(level); + + if (pte && pte_decrypted(*pte)) + found += size / PAGE_SIZE; + + addr += size; + } + + seq_printf(m, "Number of unshared pages in kernel page tables: %16lu\n", + found); + seq_printf(m, "Number of pages accounted as unshared: %16ld\n", + atomic_long_read(&nr_shared)); + return 0; +} + +static int tdx_shared_memory_open(struct inode *inode, struct file *file) +{ + return single_open(file, tdx_shared_memory_show, NULL); +} + +static const struct file_operations tdx_shared_memory_fops = { + .open = tdx_shared_memory_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static __init int debug_tdx_shared_memory(void) +{ + if (!cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) + return 0; + + debugfs_create_file("tdx_shared_memory", S_IRUSR, arch_debugfs_dir, + NULL, &tdx_shared_memory_fops); + return 0; +} +fs_initcall(debug_tdx_shared_memory); +#endif -- 2.41.0