From patchwork Wed Dec 20 07:29:28 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Haozhong Zhang X-Patchwork-Id: 10125151 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 3978360388 for ; Wed, 20 Dec 2017 07:30:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4E16B296A0 for ; Wed, 20 Dec 2017 07:30:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 42C07296CC; Wed, 20 Dec 2017 07:30:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E90CF296A0 for ; Wed, 20 Dec 2017 07:30:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754493AbdLTHaA (ORCPT ); Wed, 20 Dec 2017 02:30:00 -0500 Received: from mga04.intel.com ([192.55.52.120]:40910 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754385AbdLTH3z (ORCPT ); Wed, 20 Dec 2017 02:29:55 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Dec 2017 23:29:54 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.45,430,1508828400"; d="scan'208";a="17525240" Received: from hz-desktop.sh.intel.com (HELO localhost) ([10.239.159.142]) by orsmga001.jf.intel.com with ESMTP; 19 Dec 2017 23:29:50 -0800 From: Haozhong Zhang To: kvm@vger.kernel.org, x86@kernel.org Cc: linux-kernel@vger.kernel.org, Paolo Bonzini , rkrcmar@redhat.com, Xiao Guangrong , Dan Williams , ivan.d.cuevas.escareno@intel.com, karthik.kumar@intel.com, Konrad Rzeszutek Wilk , Olif Chapman , Mikulas Patocka , Haozhong Zhang , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Tom Lendacky Subject: [PATCH v6 1/2] x86/mm: add a function to check if a pfn is UC/UC-/WCee Date: Wed, 20 Dec 2017 15:29:28 +0800 Message-Id: <20171220072929.5200-2-haozhong.zhang@intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171220072929.5200-1-haozhong.zhang@intel.com> References: <20171220072929.5200-1-haozhong.zhang@intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Check whether the PAT memory type of a pfn cannot be overridden by MTRR UC memory type, i.e. the PAT memory type is UC, UC- or WC. This function will be used by KVM to determine whether it needs to map a host pfn to guest with UC memory type. Signed-off-by: Haozhong Zhang Reviewed-by: Xiao Guangrong --- arch/x86/include/asm/pat.h | 2 ++ arch/x86/mm/pat.c | 19 +++++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/arch/x86/include/asm/pat.h b/arch/x86/include/asm/pat.h index 8a3ee355b422..9a217a18523b 100644 --- a/arch/x86/include/asm/pat.h +++ b/arch/x86/include/asm/pat.h @@ -22,4 +22,6 @@ int io_reserve_memtype(resource_size_t start, resource_size_t end, void io_free_memtype(resource_size_t start, resource_size_t end); +bool pat_immune_to_uc_mtrr(unsigned long pfn); + #endif /* _ASM_X86_PAT_H */ diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index fe7d57a8fb60..2231a84c3d34 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -677,6 +677,25 @@ static enum page_cache_mode lookup_memtype(u64 paddr) return rettype; } +/** + * Check whether the PAT memory type of @pfn cannot be overridden by + * UC MTRR memory type. + * + * Only to be called when PAT is enabled. + * + * Returns true, if the PAT memory type of @pfn is UC, UC-, or WC. + * Returns false in other cases. + */ +bool pat_immune_to_uc_mtrr(unsigned long pfn) +{ + enum page_cache_mode cm = lookup_memtype(PFN_PHYS(pfn)); + + return cm == _PAGE_CACHE_MODE_UC || + cm == _PAGE_CACHE_MODE_UC_MINUS || + cm == _PAGE_CACHE_MODE_WC; +} +EXPORT_SYMBOL_GPL(pat_immune_to_uc_mtrr); + /** * io_reserve_memtype - Request a memory type mapping for a region of memory * @start: start (physical address) of the region