Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752482AbaKCNHh (ORCPT ); Mon, 3 Nov 2014 08:07:37 -0500 Received: from cantor2.suse.de ([195.135.220.15]:49719 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751670AbaKCNCN (ORCPT ); Mon, 3 Nov 2014 08:02:13 -0500 From: Juergen Gross To: hpa@zytor.com, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, stefan.bader@canonical.com, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, konrad.wilk@oracle.com, ville.syrjala@linux.intel.com, david.vrabel@citrix.com, jbeulich@suse.com, toshi.kani@hp.com, plagnioj@jcrosoft.com, tomi.valkeinen@ti.com, bhelgaas@google.com Cc: Juergen Gross Subject: [PATCH V6 00/18] x86: Full support of PAT Date: Mon, 3 Nov 2014 14:01:46 +0100 Message-Id: <1415019724-4317-1-git-send-email-jgross@suse.com> X-Mailer: git-send-email 1.8.4.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The x86 architecture offers via the PAT (Page Attribute Table) a way to specify different caching modes in page table entries. The PAT MSR contains 8 entries each specifying one of 6 possible cache modes. A pte references one of those entries via 3 bits: _PAGE_PAT, _PAGE_PWT and _PAGE_PCD. The Linux kernel currently supports only 4 different cache modes. The PAT MSR is set up in a way that the setting of _PAGE_PAT in a pte doesn't matter: the top 4 entries in the PAT MSR are the same as the 4 lower entries. This results in the kernel not supporting e.g. write-through mode. Especially this cache mode would speed up drivers of video cards which now have to use uncached accesses. OTOH some old processors (Pentium) don't support PAT correctly and the Xen hypervisor has been using a different PAT MSR configuration for some time now and can't change that as this setting is part of the ABI. This patch set abstracts the cache mode from the pte and introduces tables to translate between cache mode and pte bits (the default cache mode "write back" is hard-wired to PAT entry 0). The tables are statically initialized with values being compatible to old processors and current usage. As soon as the PAT MSR is changed (or - in case of Xen - is read at boot time) the tables are changed accordingly. Requests of mappings with special cache modes are always possible now, in case they are not supported there will be a fallback to a compatible but slower mode. Summing it up, this patch set adds the following features: - capability to support WT and WP cache modes on processors with full PAT support - processors with no or uncorrect PAT support are still working as today, even if WT or WP cache mode are selected by drivers for some pages - reduction of Xen special handling regarding cache mode Changes in V6: - add new patch 10 (x86: Remove looking for setting of _PAGE_PAT_LARGE in pageattr.c) as suggested by Thomas Gleixner - replaced SOB of Stefan Bader by "Based-on-patch-by:" as suggested by Borislav Petkov Changes in V5: - split up first patch as requested by Ingo Molnar and Thomas Gleixner - add a helper function in pat_init_cache_modes() as requested by Ingo Molnar Changes in V4: - rebased to 3.18-rc2 Changes in V3: - corrected two minor nits (UC_MINUS, again) detected by Toshi Kani Changes in V2: - simplified handling of PAT MSR write under Xen as suggested by David Vrabel - removed resetting of pat_enabled under Xen - two small corrections requested by Toshi Kani (UC_MINUS cache mode in vermilion driver, fix 32 bit kernel build failure) - correct build error on non-x86 arch by moving definition of update_cache_mode_entry() to x86 specific header Changes since RFC: - renamed functions and variables as suggested by Toshi Kani - corrected cache mode bits for WT and WP - modified handling of PAT MSR write under Xen as suggested by Jan Beulich Juergen Gross (18): x86: Make page cache mode a real type x86: Use new cache mode type in include/asm/fb.h x86: Use new cache mode type in drivers/video/fbdev/gbefb.c x86: Use new cache mode type in drivers/video/fbdev/vermilion x86: Use new cache mode type in arch/x86/pci x86: Use new cache mode type in arch/x86/mm/init_64.c x86: Use new cache mode type in asm/pgtable.h x86: Use new cache mode type in mm/iomap_32.c x86: Use new cache mode type in track_pfn_remap() and track_pfn_insert() x86: Remove looking for setting of _PAGE_PAT_LARGE in pageattr.c x86: Use new cache mode type in setting page attributes x86: Use new cache mode type in mm/ioremap.c x86: Use new cache mode type in memtype related functions x86: Clean up pgtable_types.h x86: Support PAT bit in pagetable dump for lower levels x86: Respect PAT bit when copying pte values between large and normal pages x86: Enable PAT to use cache mode translation tables xen: Support Xen pv-domains using PAT arch/x86/include/asm/cacheflush.h | 38 ++++--- arch/x86/include/asm/fb.h | 6 +- arch/x86/include/asm/io.h | 2 +- arch/x86/include/asm/pat.h | 7 +- arch/x86/include/asm/pgtable.h | 19 ++-- arch/x86/include/asm/pgtable_types.h | 96 ++++++++++++---- arch/x86/mm/dump_pagetables.c | 24 ++-- arch/x86/mm/init.c | 37 +++++++ arch/x86/mm/init_64.c | 9 +- arch/x86/mm/iomap_32.c | 12 +- arch/x86/mm/ioremap.c | 63 ++++++----- arch/x86/mm/mm_internal.h | 2 + arch/x86/mm/pageattr.c | 84 ++++++++------ arch/x86/mm/pat.c | 176 +++++++++++++++++++----------- arch/x86/mm/pat_internal.h | 22 ++-- arch/x86/mm/pat_rbtree.c | 8 +- arch/x86/pci/i386.c | 4 +- arch/x86/xen/enlighten.c | 25 ++--- arch/x86/xen/mmu.c | 47 +------- arch/x86/xen/xen-ops.h | 1 - drivers/video/fbdev/gbefb.c | 3 +- drivers/video/fbdev/vermilion/vermilion.c | 6 +- 22 files changed, 412 insertions(+), 279 deletions(-) -- 1.8.4.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/