1. 25 11月, 2016 1 次提交
  2. 21 11月, 2016 6 次提交
  3. 20 11月, 2016 5 次提交
  4. 18 11月, 2016 2 次提交
  5. 17 11月, 2016 1 次提交
    • A
      x86/boot: Avoid warning for zero-filling .bss · 553bbc11
      Arnd Bergmann 提交于
      The latest binutils are warning about a .fill directive with an explicit
      value in a .bss section:
      
        arch/x86/kernel/head_32.S: Assembler messages:
        arch/x86/kernel/head_32.S:677: Warning: ignoring fill value in section `.bss..page_aligned'
        arch/x86/kernel/head_32.S:679: Warning: ignoring fill value in section `.bss..page_aligned'
      
      This comes from the 'ENTRY()' macro padding the space between the symbols
      with 'nop' via:
      
        .align 4,0x90
      
      Open-coding the .globl directive without the padding avoids that warning,
      as all the symbols are already page aligned.
      Signed-off-by: NArnd Bergmann <arnd@arndb.de>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/20161116141726.2013389-1-arnd@arndb.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      553bbc11
  6. 16 11月, 2016 3 次提交
  7. 15 11月, 2016 1 次提交
  8. 13 11月, 2016 2 次提交
    • M
      x86/efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y · f6697df3
      Matt Fleming 提交于
      Booting an EFI mixed mode kernel has been crashing since commit:
      
        e37e43a4 ("x86/mm/64: Enable vmapped stacks (CONFIG_HAVE_ARCH_VMAP_STACK=y)")
      
      The user-visible effect in my test setup was the kernel being unable
      to find the root file system ramdisk. This was likely caused by silent
      memory or page table corruption.
      
      Enabling CONFIG_DEBUG_VIRTUAL=y immediately flagged the thunking code as
      abusing virt_to_phys() because it was passing addresses that were not
      part of the kernel direct mapping.
      
      Use the slow version instead, which correctly handles all memory
      regions by performing a page table walk.
      Suggested-by: NAndy Lutomirski <luto@amacapital.net>
      Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-efi@vger.kernel.org
      Link: http://lkml.kernel.org/r/20161112210424.5157-3-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f6697df3
    • B
      x86/efi: Fix EFI memmap pointer size warning · 02e56902
      Borislav Petkov 提交于
      Fix this when building on 32-bit:
      
        arch/x86/platform/efi/efi.c: In function ‘__efi_enter_virtual_mode’:
        arch/x86/platform/efi/efi.c:911:5: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
             (efi_memory_desc_t *)pa);
             ^
        arch/x86/platform/efi/efi.c:918:5: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
             (efi_memory_desc_t *)pa);
             ^
      
      The @pa local variable is declared as phys_addr_t and that is a u64 when
      CONFIG_PHYS_ADDR_T_64BIT=y. (The last is enabled on 32-bit on a PAE
      build.)
      
      However, its value comes from __pa() which is basically doing pointer
      arithmetic and checking, and returns unsigned long as it is the native
      pointer width.
      
      So let's use an unsigned long too. It should be fine to do so because
      the later users cast it to a pointer too.
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-efi@vger.kernel.org
      Link: http://lkml.kernel.org/r/20161112210424.5157-2-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
      02e56902
  9. 12 11月, 2016 2 次提交
    • A
      crypto: aesni: shut up -Wmaybe-uninitialized warning · beae2c9e
      Arnd Bergmann 提交于
      The rfc4106 encrypy/decrypt helper functions cause an annoying
      false-positive warning in allmodconfig if we turn on
      -Wmaybe-uninitialized warnings again:
      
        arch/x86/crypto/aesni-intel_glue.c: In function ‘helper_rfc4106_decrypt’:
        include/linux/scatterlist.h:67:31: warning: ‘dst_sg_walk.sg’ may be used uninitialized in this function [-Wmaybe-uninitialized]
      
      The problem seems to be that the compiler doesn't track the state of the
      'one_entry_in_sg' variable across the kernel_fpu_begin/kernel_fpu_end
      section.
      
      This takes the easy way out by adding a bogus initialization, which
      should be harmless enough to get the patch into v4.9 so we can turn on
      this warning again by default without producing useless output.  A
      follow-up patch for v4.10 rearranges the code to make the warning go
      away.
      Signed-off-by: NArnd Bergmann <arnd@arndb.de>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      beae2c9e
    • A
      x86: apm: avoid uninitialized data · 3a6d8676
      Arnd Bergmann 提交于
      apm_bios_call() can fail, and return a status in its argument structure.
      If that status however is zero during a call from
      apm_get_power_status(), we end up using data that may have never been
      set, as reported by "gcc -Wmaybe-uninitialized":
      
        arch/x86/kernel/apm_32.c: In function ‘apm’:
        arch/x86/kernel/apm_32.c:1729:17: error: ‘bx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
        arch/x86/kernel/apm_32.c:1835:5: error: ‘cx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
        arch/x86/kernel/apm_32.c:1730:17: note: ‘cx’ was declared here
        arch/x86/kernel/apm_32.c:1842:27: error: ‘dx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
        arch/x86/kernel/apm_32.c:1731:17: note: ‘dx’ was declared here
      
      This changes the function to return "APM_NO_ERROR" here, which makes the
      code more robust to broken BIOS versions, and avoids the warning.
      Signed-off-by: NArnd Bergmann <arnd@arndb.de>
      Reviewed-by: NJiri Kosina <jkosina@suse.cz>
      Reviewed-by: NLuis R. Rodriguez <mcgrof@kernel.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3a6d8676
  10. 11 11月, 2016 1 次提交
  11. 10 11月, 2016 3 次提交
    • S
      x86/kexec: add -fno-PIE · 90944e40
      Sebastian Andrzej Siewior 提交于
      If the gcc is configured to do -fPIE by default then the build aborts
      later with:
      | Unsupported relocation type: unknown type rel type name (29)
      
      Tagging it stable so it is possible to compile recent stable kernels as
      well.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
      Signed-off-by: NMichal Marek <mmarek@suse.com>
      90944e40
    • T
      x86/cpu: Deal with broken firmware (VMWare/XEN) · d49597fd
      Thomas Gleixner 提交于
      Both ACPI and MP specifications require that the APIC id in the respective
      tables must be the same as the APIC id in CPUID.
      
      The kernel retrieves the physical package id from the APIC id during the
      ACPI/MP table scan and builds the physical to logical package map. The
      physical package id which is used after a CPU comes up is retrieved from
      CPUID. So we rely on ACPI/MP tables and CPUID agreeing in that respect.
      
      There exist VMware and XEN implementations which violate the spec. As a
      result the physical to logical package map, which relies on the ACPI/MP
      tables does not work on those systems, because the CPUID initialized
      physical package id does not match the firmware id. This causes system
      crashes and malfunction due to invalid package mappings.
      
      The only way to cure this is to sanitize the physical package id after the
      CPUID enumeration and yell when the APIC ids are different. Fix up the
      initial APIC id, which is fine as it is only used printout purposes.
      
      If the physical package IDs differ yell and use the package information
      from the ACPI/MP tables so the existing logical package map just works.
      
      Chas provided the resulting dmesg output for his affected 4 virtual
      sockets, 1 core per socket VM:
      
      [Firmware Bug]: CPU1: APIC id mismatch. Firmware: 1 CPUID: 2
      [Firmware Bug]: CPU1: Using firmware package id 1 instead of 2
      ....
      
      Reported-and-tested-by: "Charles (Chas) Williams" <ciwillia@brocade.com>,
      Reported-by: NM. Vefa Bicakci <m.v.b@runbox.com>
      Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Alok Kataria <akataria@vmware.com>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: #4.6+ <stable@vger,kernel.org>
      Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1611091613540.3501@nanosSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      d49597fd
    • Y
      x86/cpu/AMD: Fix cpu_llc_id for AMD Fam17h systems · b0b6e868
      Yazen Ghannam 提交于
      cpu_llc_id (Last Level Cache ID) derivation on AMD Fam17h has an
      underflow bug when extracting the socket_id value. It starts from 0
      so subtracting 1 from it will result in an invalid value. This breaks
      scheduling topology later on since the cpu_llc_id will be incorrect.
      
      For example, the the cpu_llc_id of the *other* CPU in the loops in
      set_cpu_sibling_map() underflows and we're generating the funniest
      thread_siblings masks and then when I run 8 threads of nbench, they get
      spread around the LLC domains in a very strange pattern which doesn't
      give you the normal scheduling spread one would expect for performance.
      
      Other things like EDAC use cpu_llc_id so they will be b0rked too.
      
      So, the APIC ID is preset in APICx020 for bits 3 and above: they contain
      the core complex, node and socket IDs.
      
      The LLC is at the core complex level so we can find a unique cpu_llc_id
      by right shifting the APICID by 3 because then the least significant bit
      will be the Core Complex ID.
      Tested-by: NBorislav Petkov <bp@suse.de>
      Signed-off-by: NYazen Ghannam <Yazen.Ghannam@amd.com>
      [ Cleaned up and extended the commit message. ]
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Acked-by: NThomas Gleixner <tglx@linutronix.de>
      Cc: <stable@vger.kernel.org> # v4.4..
      Cc: Aravind Gopalakrishnan <aravindksg.lkml@gmail.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Fixes: 3849e91f ("x86/AMD: Fix last level cache topology for AMD Fam17h systems")
      Link: http://lkml.kernel.org/r/20161108083506.rvqb5h4chrcptj7d@pd.tnicSigned-off-by: NIngo Molnar <mingo@kernel.org>
      b0b6e868
  12. 07 11月, 2016 1 次提交
  13. 03 11月, 2016 3 次提交
  14. 29 10月, 2016 1 次提交
    • T
      x86/smpboot: Init apic mapping before usage · 1e90a13d
      Thomas Gleixner 提交于
      The recent changes, which forced the registration of the boot cpu on UP
      systems, which do not have ACPI tables, have been fixed for systems w/o
      local APIC, but left a wreckage for systems which have neither ACPI nor
      mptables, but the CPU has an APIC, e.g. virtualbox.
      
      The boot process crashes in prefill_possible_map() as it wants to register
      the boot cpu, which needs to access the local apic, but the local APIC is
      not yet mapped.
      
      There is no reason why init_apic_mapping() can't be invoked before
      prefill_possible_map(). So instead of playing another silly early mapping
      game, as the ACPI/mptables code does, we just move init_apic_mapping()
      before the call to prefill_possible_map().
      
      In hindsight, I should have noticed that combination earlier.
      
      Sorry for the churn (also in stable)!
      
      Fixes: ff856051 ("x86/boot/smp: Don't try to poke disabled/non-existent APIC")
      Reported-and-debugged-by: NMichal Necasek <michal.necasek@oracle.com>
      Reported-and-tested-by: NWolfgang Bauer <wbauer@tmo.at>
      Cc: prarit@redhat.com
      Cc: ville.syrjala@linux.intel.com
      Cc: michael.thayer@oracle.com
      Cc: knut.osmundsen@oracle.com
      Cc: frank.mehnert@oracle.com
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: stable@vger.kernel.org
      Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1610282114380.5053@nanosSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      1e90a13d
  15. 28 10月, 2016 5 次提交
    • I
      KVM: x86: fix wbinvd_dirty_mask use-after-free · bd768e14
      Ido Yariv 提交于
      vcpu->arch.wbinvd_dirty_mask may still be used after freeing it,
      corrupting memory. For example, the following call trace may set a bit
      in an already freed cpu mask:
          kvm_arch_vcpu_load
          vcpu_load
          vmx_free_vcpu_nested
          vmx_free_vcpu
          kvm_arch_vcpu_free
      
      Fix this by deferring freeing of wbinvd_dirty_mask.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: NIdo Yariv <ido@wizery.com>
      Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
      bd768e14
    • I
      perf/x86/intel: Honour the CPUID for number of fixed counters in hypervisors · f92b7604
      Imre Palik 提交于
      perf doesn't seem to honour the number of fixed counters specified by CPUID
      leaf 0xa. It always assumes that Intel CPUs have at least 3 fixed counters.
      
      So if some of the fixed counters are masked out by the hypervisor, it still
      tries to check/set them.
      
      This patch makes perf behave nicer when the kernel is running under a
      hypervisor that doesn't expose all the counters.
      
      This patch contains some ideas from Matt Wilson.
      Signed-off-by: NImre Palik <imrep@amazon.de>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Reviewed-by: NAndi Kleen <ak@linux.intel.com>
      Cc: Alexander Kozyrev <alexander.kozyrev@intel.com>
      Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
      Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
      Cc: Artyom Kuanbekov <artyom.kuanbekov@intel.com>
      Cc: David Carrillo-Cisneros <davidcc@google.com>
      Cc: David Woodhouse <dwmw@amazon.co.uk>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Jiri Olsa <jolsa@redhat.com>
      Cc: Kan Liang <kan.liang@intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Matt Wilson <msw@amazon.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Stephane Eranian <eranian@google.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/1477037939-15605-1-git-send-email-imrep.amz@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f92b7604
    • B
      x86/microcode/AMD: Fix more fallout from CONFIG_RANDOMIZE_MEMORY=y · 1c27f646
      Borislav Petkov 提交于
      We needed the physical address of the container in order to compute the
      offset within the relocated ramdisk. And we did this by doing __pa() on
      the virtual address.
      
      However, __pa() does checks whether the physical address is within
      PAGE_OFFSET and __START_KERNEL_map - see __phys_addr() - which fail
      if we have CONFIG_RANDOMIZE_MEMORY enabled: we feed a virtual address
      which *doesn't* have the randomization offset into a function which uses
      PAGE_OFFSET which *does* have that offset.
      
      This makes this check fire:
      
      	VIRTUAL_BUG_ON((x > y) || !phys_addr_valid(x));
      			^^^^^^
      
      due to the randomization offset.
      
      The fix is as simple as using __pa_nodebug() because we do that
      randomization offset accounting later in that function ourselves.
      Reported-by: NBob Peterson <rpeterso@redhat.com>
      Tested-by: NBob Peterson <rpeterso@redhat.com>
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Cc: Andreas Gruenbacher <agruenba@redhat.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mel Gorman <mgorman@techsingularity.net>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Whitehouse <swhiteho@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-mm <linux-mm@kvack.org>
      Cc: stable@vger.kernel.org # 4.9
      Link: http://lkml.kernel.org/r/20161027123623.j2jri5bandimboff@pd.tnicSigned-off-by: NIngo Molnar <mingo@kernel.org>
      1c27f646
    • M
      kconfig.h: remove config_enabled() macro · c0a0aba8
      Masahiro Yamada 提交于
      The use of config_enabled() is ambiguous.  For config options,
      IS_ENABLED(), IS_REACHABLE(), etc.  will make intention clearer.
      Sometimes config_enabled() has been used for non-config options because
      it is useful to check whether the given symbol is defined or not.
      
      I have been tackling on deprecating config_enabled(), and now is the
      time to finish this work.
      
      Some new users have appeared for v4.9-rc1, but it is trivial to replace
      them:
      
       - arch/x86/mm/kaslr.c
        replace config_enabled() with IS_ENABLED() because
        CONFIG_X86_ESPFIX64 and CONFIG_EFI are boolean.
      
       - include/asm-generic/export.h
        replace config_enabled() with __is_defined().
      
      Then, config_enabled() can be removed now.
      
      Going forward, please use IS_ENABLED(), IS_REACHABLE(), etc. for config
      options, and __is_defined() for non-config symbols.
      
      Link: http://lkml.kernel.org/r/1476616078-32252-1-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
      Acked-by: NIngo Molnar <mingo@kernel.org>
      Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>
      Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Michal Marek <mmarek@suse.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Thomas Garnier <thgarnie@google.com>
      Cc: Paul Bolle <pebolle@tiscali.nl>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c0a0aba8
    • B
      kvm/x86: Show WRMSR data is in hex · 796f4687
      Borislav Petkov 提交于
      Add the "0x" prefix to the error messages format to make it unambiguous
      about what kind of value we're talking about.
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: "Radim Krčmář" <rkrcmar@redhat.com>
      Message-Id: <20161027181445.25319-1-bp@alien8.de>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      796f4687
  16. 27 10月, 2016 1 次提交
  17. 26 10月, 2016 2 次提交
    • S
      x86: Fix export for mcount and __fentry__ · 5de0a8c0
      Steven Rostedt 提交于
      Commit 784d5699 ("x86: move exports to actual definitions") removed the
      EXPORT_SYMBOL(__fentry__) and EXPORT_SYMBOL(mcount) from x8664_ksyms_64.c,
      and added EXPORT_SYMBOL(function_hook) in mcount_64.S instead. The problem
      is that function_hook isn't a function at all, but a macro that is defined
      as either mcount or __fentry__ depending on the support from gcc.
      
      Originally, I thought this was a macro issue, like what __stringify()
      is used for. But the problem is a bit deeper. The Makefile.build has
      some magic that does post processing of files to create the CRC
      bindings. It does some searches for EXPORT_SYMBOL() and because it
      finds a macro name and not the actual functions, this causes
      function_hook not to be converted into mcount or __fentry__ and they
      are missed.
      
      Instead of adding more magic to Makefile.build, just add
      EXPORT_SYMBOL() for mcount and __fentry__ where the ifdef is used.
      Since this is assembly and not C, it doesn't require being set after
      the function is defined.
      Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      Tested-by: NBorislav Petkov <bp@alien8.de>
      Cc: Gabriel C <nix.or.die@gmail.com>
      Cc: Nicholas Piggin <npiggin@gmail.com>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Link: http://lkml.kernel.org/r/20161024150148.4f9d90e4@gandalf.local.homeSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      5de0a8c0
    • D
      x86/io: add interface to reserve io memtype for a resource range. (v1.1) · 8ef42276
      Dave Airlie 提交于
      A recent change to the mm code in:
      87744ab3 mm: fix cache mode tracking in vm_insert_mixed()
      
      started enforcing checking the memory type against the registered list for
      amixed pfn insertion mappings. It happens that the drm drivers for a number
      of gpus relied on this being broken. Currently the driver only inserted
      VRAM mappings into the tracking table when they came from the kernel,
      and userspace mappings never landed in the table. This led to a regression
      where all the mapping end up as UC instead of WC now.
      
      I've considered a number of solutions but since this needs to be fixed
      in fixes and not next, and some of the solutions were going to introduce
      overhead that hadn't been there before I didn't consider them viable at
      this stage. These mainly concerned hooking into the TTM io reserve APIs,
      but these API have a bunch of fast paths I didn't want to unwind to add
      this to.
      
      The solution I've decided on is to add a new API like the arch_phys_wc
      APIs (these would have worked but wc_del didn't take a range), and
      use them from the drivers to add a WC compatible mapping to the table
      for all VRAM on those GPUs. This means we can then create userspace
      mapping that won't get degraded to UC.
      
      v1.1: use CONFIG_X86_PAT + add some comments in io.h
      
      Cc: Toshi Kani <toshi.kani@hp.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: x86@kernel.org
      Cc: mcgrof@suse.com
      Cc: Dan Williams <dan.j.williams@intel.com>
      Acked-by: NIngo Molnar <mingo@kernel.org>
      Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NDave Airlie <airlied@redhat.com>
      8ef42276