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 879DF10E8 for ; Tue, 5 Dec 2023 00:45:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="d4uxwGRq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701737135; x=1733273135; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=RP/Va3aoGG5zb/Y76A/szY23yia8vizTXE1CbaIASh0=; b=d4uxwGRqsLO8MY5jI7Rcaw3E7aOZ5O/M8KFi3bGWq+mRn4IMZlp+2owi 1KpCn57uS8n+9Omo55V6OBvHJk0GPt9oVZRDARl4HVPY5L14g8eNe4Boe 61zxw4odZK9P15QM082Q5Aec2cgeRPelMies7aJa2EL7RarnKPkuvNw7M zAIrVGHY4+BVg/dGmGHk76tQFljoDQR5o5inT5IrO77L7+R5Zo3q+uOxg h2b04YSBVyTwz1ZopWjS8hloiNRsFRbfIF7AP/BbcaoSXUEC3e0PCLIQV XGV0ZusYFGIrx1ii6KaR90TGWra5ph4cm4wJPczcjbBGAmfLG44tPM2bC w==; X-IronPort-AV: E=McAfee;i="6600,9927,10914"; a="392688667" X-IronPort-AV: E=Sophos;i="6.04,251,1695711600"; d="scan'208";a="392688667" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2023 16:45:34 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10914"; a="888704404" X-IronPort-AV: E=Sophos;i="6.04,251,1695711600"; d="scan'208";a="888704404" Received: from abijaz-mobl2.ger.corp.intel.com (HELO box.shutemov.name) ([10.252.61.240]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Dec 2023 16:45:30 -0800 Received: by box.shutemov.name (Postfix, from userid 1000) id 8959010A44A; Tue, 5 Dec 2023 03:45:20 +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 , "Kalra, Ashish" , Sean Christopherson , "Huang, Kai" , Baoquan He , kexec@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv4 09/14] x86/tdx: Account shared memory Date: Tue, 5 Dec 2023 03:45:05 +0300 Message-ID: <20231205004510.27164-10-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231205004510.27164-1-kirill.shutemov@linux.intel.com> References: <20231205004510.27164-1-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 second 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 | 69 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 2d90043a0e91..fcc159497554 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) { @@ -820,6 +828,11 @@ 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; } @@ -895,3 +908,59 @@ 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; + + cond_resched(); + } + + seq_printf(m, "Number of shared pages in kernel page tables: %16lu\n", + found); + seq_printf(m, "Number of pages accounted as shared: %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