Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932340AbdLTHaC (ORCPT ); Wed, 20 Dec 2017 02:30:02 -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 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.45,430,1508828400"; d="scan'208";a="17525240" 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: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1813 Lines: 55 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 -- 2.14.1