On Sun, 28 May 2017, Andy Lutomirski wrote:
> On Sun, May 28, 2017 at 11:18 AM, Bernhard Held <[email protected]> wrote:
> > Hi,
> >
> > this patch breaks the boot of my kernel. The last message is "Booting
> > the kernel.".
> >
> > My setup might be unusual: I'm running a Xenon E5450 (LGA 771) in a
> > Gigbayte G33-DS3R board (LGA 775). The BIOS is patched with the
> > microcode of the E5450 and recognizes the CPU.
> >
> > Please find below the dmesg of a the latest kernel w/o the PAT-patch.
> > I'm happy to provide more information or to test patches.
>
> I think this patch is bogus. pat_enabled() sure looks like it's
> supposed to return true if PAT is *enabled*, and these days PAT is
> "enabled" even if there's no HW PAT support. Even if the patch were
> somehow correct, it should have been split up into two patches, one to
> change pat_enabled() and one to use this_cpu_has().
>
> Ingo, I'd suggest reverting the patch, cc-ing stable on the revert so
> -stable knows not to backport it, and starting over with the fix.
> >From very brief inspection, the right fix is to make sure that
> pat_init(), or at least init_cache_modes(), gets called on the
> affected CPUs.
>
> --Andy
Hi
Here I send the second version of the patch. It drops the change from
boot_cpu_has(X86_FEATURE_PAT) to this_cpu_has(X86_FEATURE_PAT) (that
caused kernel to be unbootable for some people).
Another change is that setup_arch() calls init_cache_modes() if PAT is
disabled, so that init_cache_modes() is always called.
Mikulas
From: Mikulas Patocka <[email protected]>
In the file arch/x86/mm/pat.c, there's a variable __pat_enabled. The
variable is set to 1 by default and the function pat_init() sets
__pat_enabled to 0 if the CPU doesn't support PAT.
However, on AMD K6-3 CPU, the processor initialization code never calls
pat_init() and so __pat_enabled stays 1 and the function pat_enabled()
returns true, even though the K6-3 CPU doesn't support PAT.
The result of this bug is that this warning is produced when attemting to
start the Xserver and the Xserver doesn't start (fork() returns ENOMEM).
Another symptom of this bug is that the framebuffer driver doesn't set the
K6-3 MTRR registers.
This patch changes pat_enabled() so that it returns true only if pat
initialization was actually done.
As Andy Lutomirski suggested, we also need to call init_cache_modes() if
pat was not initialized, so we call it after mtrr_bp_init()
(mtrr_bp_init() would or wouldn't call pat_init()). Note that
init_cache_modes() detects if it was called more than once and does
nothing in that case.
x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3891 at arch/x86/mm/pat.c:1020 untrack_pfn+0x5c/0x9f
Modules linked in: blowfish_generic blowfish_common cbc dm_crypt dm_loop msr configfs cpufreq_userspace cpufreq_powersave cpufreq_ondemand cpufreq_conservative ext4 crc16 jbd2 mbcache hpfs nls_cp852 msdos fat matroxfb_base matroxfb_g450 matroxfb_accel cfbfillrect cfbimgblt cfbcopyarea matroxfb_DAC1064 g450_pll matroxfb_misc floppy snd_usb_audio snd_hwdep snd_usbmidi_lib snd_seq_midi snd_seq_midi_event snd_rawmidi snd_pcm snd_seq snd_seq_device snd_timer hid_generic snd usbhid hid soundcore powernow_k6 pcspkr evdev e1000 ehci_pci uhci_hcd ehci_hcd usbcore usb_common dm_mod pata_it821x unix
CPU: 0 PID: 3891 Comm: Xorg Not tainted 4.11.0-rc6-test+ #35
Hardware name: System Manufacturer Product Name/VA-503A, BIOS 4.51 PG 08/02/00
Call Trace:
? __warn+0xab/0xc0
? untrack_pfn+0x5c/0x9f
? warn_slowpath_null+0xf/0x13
? untrack_pfn+0x5c/0x9f
? unmap_single_vma+0x43/0x66
? unmap_vmas+0x24/0x30
? exit_mmap+0x3c/0xa5
? __mmput+0xf/0x76
? copy_process.part.76+0xb43/0x1129
? _do_fork+0x96/0x177
? do_int80_syscall_32+0x3e/0x4c
? entry_INT80_32+0x2a/0x2a
---[ end trace 8726f9d9fa90d702 ]---
x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining
Signed-off-by: Mikulas Patocka <[email protected]>
Cc: [email protected] # v4.2+
---
arch/x86/include/asm/pat.h | 1 +
arch/x86/kernel/setup.c | 2 ++
arch/x86/mm/pat.c | 10 ++++++----
3 files changed, 9 insertions(+), 4 deletions(-)
Index: linux-stable/arch/x86/mm/pat.c
===================================================================
--- linux-stable.orig/arch/x86/mm/pat.c
+++ linux-stable/arch/x86/mm/pat.c
@@ -40,7 +40,6 @@
static bool boot_cpu_done;
static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);
-static void init_cache_modes(void);
void pat_disable(const char *reason)
{
@@ -65,9 +64,11 @@ static int __init nopat(char *str)
}
early_param("nopat", nopat);
+static bool __read_mostly __pat_initialized = false;
+
bool pat_enabled(void)
{
- return !!__pat_enabled;
+ return __pat_initialized;
}
EXPORT_SYMBOL_GPL(pat_enabled);
@@ -225,6 +226,7 @@ static void pat_bsp_init(u64 pat)
}
wrmsrl(MSR_IA32_CR_PAT, pat);
+ __pat_initialized = true;
__init_cache_modes(pat);
}
@@ -242,7 +244,7 @@ static void pat_ap_init(u64 pat)
wrmsrl(MSR_IA32_CR_PAT, pat);
}
-static void init_cache_modes(void)
+void init_cache_modes(void)
{
u64 pat = 0;
static int init_cm_done;
@@ -306,7 +308,7 @@ void pat_init(void)
u64 pat;
struct cpuinfo_x86 *c = &boot_cpu_data;
- if (!pat_enabled()) {
+ if (!__pat_enabled) {
init_cache_modes();
return;
}
Index: linux-stable/arch/x86/include/asm/pat.h
===================================================================
--- linux-stable.orig/arch/x86/include/asm/pat.h
+++ linux-stable/arch/x86/include/asm/pat.h
@@ -7,6 +7,7 @@
bool pat_enabled(void);
void pat_disable(const char *reason);
extern void pat_init(void);
+extern void init_cache_modes(void);
extern int reserve_memtype(u64 start, u64 end,
enum page_cache_mode req_pcm, enum page_cache_mode *ret_pcm);
Index: linux-stable/arch/x86/kernel/setup.c
===================================================================
--- linux-stable.orig/arch/x86/kernel/setup.c
+++ linux-stable/arch/x86/kernel/setup.c
@@ -1070,6 +1070,8 @@ void __init setup_arch(char **cmdline_p)
/* update e820 for memory not covered by WB MTRRs */
mtrr_bp_init();
+ if (!pat_enabled())
+ init_cache_modes();
if (mtrr_trim_uncached_memory(max_pfn))
max_pfn = e820__end_of_ram_pfn();
On Tue, Jun 6, 2017 at 3:49 PM, Mikulas Patocka <[email protected]> wrote:
>
>
> On Sun, 28 May 2017, Andy Lutomirski wrote:
>
>> On Sun, May 28, 2017 at 11:18 AM, Bernhard Held <[email protected]> wrote:
>> > Hi,
>> >
>> > this patch breaks the boot of my kernel. The last message is "Booting
>> > the kernel.".
>> >
>> > My setup might be unusual: I'm running a Xenon E5450 (LGA 771) in a
>> > Gigbayte G33-DS3R board (LGA 775). The BIOS is patched with the
>> > microcode of the E5450 and recognizes the CPU.
>> >
>> > Please find below the dmesg of a the latest kernel w/o the PAT-patch.
>> > I'm happy to provide more information or to test patches.
>>
>> I think this patch is bogus. pat_enabled() sure looks like it's
>> supposed to return true if PAT is *enabled*, and these days PAT is
>> "enabled" even if there's no HW PAT support. Even if the patch were
>> somehow correct, it should have been split up into two patches, one to
>> change pat_enabled() and one to use this_cpu_has().
>>
>> Ingo, I'd suggest reverting the patch, cc-ing stable on the revert so
>> -stable knows not to backport it, and starting over with the fix.
>> >From very brief inspection, the right fix is to make sure that
>> pat_init(), or at least init_cache_modes(), gets called on the
>> affected CPUs.
>>
>> --Andy
>
> Hi
>
> Here I send the second version of the patch. It drops the change from
> boot_cpu_has(X86_FEATURE_PAT) to this_cpu_has(X86_FEATURE_PAT) (that
> caused kernel to be unbootable for some people).
>
> Another change is that setup_arch() calls init_cache_modes() if PAT is
> disabled, so that init_cache_modes() is always called.
>
> Mikulas
>
>
>
> From: Mikulas Patocka <[email protected]>
>
> In the file arch/x86/mm/pat.c, there's a variable __pat_enabled. The
> variable is set to 1 by default and the function pat_init() sets
> __pat_enabled to 0 if the CPU doesn't support PAT.
>
> However, on AMD K6-3 CPU, the processor initialization code never calls
> pat_init() and so __pat_enabled stays 1 and the function pat_enabled()
> returns true, even though the K6-3 CPU doesn't support PAT.
>
> The result of this bug is that this warning is produced when attemting to
> start the Xserver and the Xserver doesn't start (fork() returns ENOMEM).
> Another symptom of this bug is that the framebuffer driver doesn't set the
> K6-3 MTRR registers.
>
> This patch changes pat_enabled() so that it returns true only if pat
> initialization was actually done.
Why? Shouldn't calling init_cache_modes() be sufficient?
--Andy
On Tue, 6 Jun 2017, Andy Lutomirski wrote:
> On Tue, Jun 6, 2017 at 3:49 PM, Mikulas Patocka <[email protected]> wrote:
> >
> >
> > On Sun, 28 May 2017, Andy Lutomirski wrote:
> >
> >> On Sun, May 28, 2017 at 11:18 AM, Bernhard Held <[email protected]> wrote:
> >> > Hi,
> >> >
> >> > this patch breaks the boot of my kernel. The last message is "Booting
> >> > the kernel.".
> >> >
> >> > My setup might be unusual: I'm running a Xenon E5450 (LGA 771) in a
> >> > Gigbayte G33-DS3R board (LGA 775). The BIOS is patched with the
> >> > microcode of the E5450 and recognizes the CPU.
> >> >
> >> > Please find below the dmesg of a the latest kernel w/o the PAT-patch.
> >> > I'm happy to provide more information or to test patches.
> >>
> >> I think this patch is bogus. pat_enabled() sure looks like it's
> >> supposed to return true if PAT is *enabled*, and these days PAT is
> >> "enabled" even if there's no HW PAT support. Even if the patch were
> >> somehow correct, it should have been split up into two patches, one to
> >> change pat_enabled() and one to use this_cpu_has().
> >>
> >> Ingo, I'd suggest reverting the patch, cc-ing stable on the revert so
> >> -stable knows not to backport it, and starting over with the fix.
> >> >From very brief inspection, the right fix is to make sure that
> >> pat_init(), or at least init_cache_modes(), gets called on the
> >> affected CPUs.
> >>
> >> --Andy
> >
> > Hi
> >
> > Here I send the second version of the patch. It drops the change from
> > boot_cpu_has(X86_FEATURE_PAT) to this_cpu_has(X86_FEATURE_PAT) (that
> > caused kernel to be unbootable for some people).
> >
> > Another change is that setup_arch() calls init_cache_modes() if PAT is
> > disabled, so that init_cache_modes() is always called.
> >
> > Mikulas
> >
> >
> >
> > From: Mikulas Patocka <[email protected]>
> >
> > In the file arch/x86/mm/pat.c, there's a variable __pat_enabled. The
> > variable is set to 1 by default and the function pat_init() sets
> > __pat_enabled to 0 if the CPU doesn't support PAT.
> >
> > However, on AMD K6-3 CPU, the processor initialization code never calls
> > pat_init() and so __pat_enabled stays 1 and the function pat_enabled()
> > returns true, even though the K6-3 CPU doesn't support PAT.
> >
> > The result of this bug is that this warning is produced when attemting to
> > start the Xserver and the Xserver doesn't start (fork() returns ENOMEM).
> > Another symptom of this bug is that the framebuffer driver doesn't set the
> > K6-3 MTRR registers.
> >
> > This patch changes pat_enabled() so that it returns true only if pat
> > initialization was actually done.
>
> Why? Shouldn't calling init_cache_modes() be sufficient?
>
> --Andy
See the function arch_phys_wc_add():
if (pat_enabled() || !mtrr_enabled())
return 0; /* Success! (We don't need to do anything.) */
ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true);
- if pat_enabled() returns true, that function doesn't set MTRRs.
pat_enabled() must return false on systems without PAT, so that MTRRs are
set.
Mikulas
On 06/07/2017 at 12:49 AM, Mikulas Patocka wrote:
> Hi
>
> Here I send the second version of the patch. It drops the change from
> boot_cpu_has(X86_FEATURE_PAT) to this_cpu_has(X86_FEATURE_PAT) (that
> caused kernel to be unbootable for some people).
>
> Another change is that setup_arch() calls init_cache_modes() if PAT is
> disabled, so that init_cache_modes() is always called.
>
> Mikulas
[PATCH v2] Works for me!
CHeers,
Bernhard
On Tue, Jun 6, 2017 at 4:21 PM, Mikulas Patocka <[email protected]> wrote:
>
>
> On Tue, 6 Jun 2017, Andy Lutomirski wrote:
>
>> On Tue, Jun 6, 2017 at 3:49 PM, Mikulas Patocka <[email protected]> wrote:
>> >
>> >
>> > On Sun, 28 May 2017, Andy Lutomirski wrote:
>> >
>> >> On Sun, May 28, 2017 at 11:18 AM, Bernhard Held <[email protected]> wrote:
>> >> > Hi,
>> >> >
>> >> > this patch breaks the boot of my kernel. The last message is "Booting
>> >> > the kernel.".
>> >> >
>> >> > My setup might be unusual: I'm running a Xenon E5450 (LGA 771) in a
>> >> > Gigbayte G33-DS3R board (LGA 775). The BIOS is patched with the
>> >> > microcode of the E5450 and recognizes the CPU.
>> >> >
>> >> > Please find below the dmesg of a the latest kernel w/o the PAT-patch.
>> >> > I'm happy to provide more information or to test patches.
>> >>
>> >> I think this patch is bogus. pat_enabled() sure looks like it's
>> >> supposed to return true if PAT is *enabled*, and these days PAT is
>> >> "enabled" even if there's no HW PAT support. Even if the patch were
>> >> somehow correct, it should have been split up into two patches, one to
>> >> change pat_enabled() and one to use this_cpu_has().
>> >>
>> >> Ingo, I'd suggest reverting the patch, cc-ing stable on the revert so
>> >> -stable knows not to backport it, and starting over with the fix.
>> >> >From very brief inspection, the right fix is to make sure that
>> >> pat_init(), or at least init_cache_modes(), gets called on the
>> >> affected CPUs.
>> >>
>> >> --Andy
>> >
>> > Hi
>> >
>> > Here I send the second version of the patch. It drops the change from
>> > boot_cpu_has(X86_FEATURE_PAT) to this_cpu_has(X86_FEATURE_PAT) (that
>> > caused kernel to be unbootable for some people).
>> >
>> > Another change is that setup_arch() calls init_cache_modes() if PAT is
>> > disabled, so that init_cache_modes() is always called.
>> >
>> > Mikulas
>> >
>> >
>> >
>> > From: Mikulas Patocka <[email protected]>
>> >
>> > In the file arch/x86/mm/pat.c, there's a variable __pat_enabled. The
>> > variable is set to 1 by default and the function pat_init() sets
>> > __pat_enabled to 0 if the CPU doesn't support PAT.
>> >
>> > However, on AMD K6-3 CPU, the processor initialization code never calls
>> > pat_init() and so __pat_enabled stays 1 and the function pat_enabled()
>> > returns true, even though the K6-3 CPU doesn't support PAT.
>> >
>> > The result of this bug is that this warning is produced when attemting to
>> > start the Xserver and the Xserver doesn't start (fork() returns ENOMEM).
>> > Another symptom of this bug is that the framebuffer driver doesn't set the
>> > K6-3 MTRR registers.
>> >
>> > This patch changes pat_enabled() so that it returns true only if pat
>> > initialization was actually done.
>>
>> Why? Shouldn't calling init_cache_modes() be sufficient?
>>
>> --Andy
>
> See the function arch_phys_wc_add():
>
> if (pat_enabled() || !mtrr_enabled())
> return 0; /* Success! (We don't need to do anything.) */
> ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true);
>
> - if pat_enabled() returns true, that function doesn't set MTRRs.
> pat_enabled() must return false on systems without PAT, so that MTRRs are
> set.
It still sounds to me like there are two bugs here that should be
treated separately.
Bug 1: A warning fires. Have you figured out why the warning fires?
Bug 2: arch_phys_wc_add() appears to be checking the wrong condition.
How about checking the right condition? It doesn't actually want to
know if PAT is enabled -- it wants to know if the PAT contains a
usable WC entry. Something like pat_has_wc() would be better, I
think.
--Andy
On Tue, 13 Jun 2017, Andy Lutomirski wrote:
> On Tue, Jun 6, 2017 at 4:21 PM, Mikulas Patocka <[email protected]> wrote:
> >
> > On Tue, 6 Jun 2017, Andy Lutomirski wrote:
> >
> >> On Tue, Jun 6, 2017 at 3:49 PM, Mikulas Patocka <[email protected]> wrote:
> >> >
> >> > This patch changes pat_enabled() so that it returns true only if pat
> >> > initialization was actually done.
> >>
> >> Why? Shouldn't calling init_cache_modes() be sufficient?
> >>
> >> --Andy
> >
> > See the function arch_phys_wc_add():
> >
> > if (pat_enabled() || !mtrr_enabled())
> > return 0; /* Success! (We don't need to do anything.) */
> > ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true);
> >
> > - if pat_enabled() returns true, that function doesn't set MTRRs.
> > pat_enabled() must return false on systems without PAT, so that MTRRs are
> > set.
>
> It still sounds to me like there are two bugs here that should be
> treated separately.
>
> Bug 1: A warning fires. Have you figured out why the warning fires?
The Xserver maps videoram and attempts to call fork() to spawn some
utility.
reserve_pfn_range is called. At the beginning of reserve_pfn_range,
want_pcm is set to 2 (_PAGE_CACHE_MODE_UC_MINUS).
reserve_pfn_range calls reserve_memtype(paddr, paddr + size, want_pcm,
&pcm);
reserve_memtype contains this code at the beginning:
if (!pat_enabled()) {
/* This is identical to page table setting without PAT */
if (new_type)
*new_type = req_type;
return 0;
} --- so, if pat_enabled() return false, it sets pcm equal to want_pcm and
there is no problem.
However, if pat_enabled() returns true, reserve_memtype goes on, it sets
actual_type = pat_x_mtrr_type(start, end, req_type); (actual_type is 2)
if (new_type)
*new_type = actual_type; (*new_type is 2)
and finally it calls rbt_memtype_check_insert(new, new_type);
rbt_memtype_check_insert calls memtype_rb_check_conflict
memtype_rb_check_conflict sets *newtype to the value 1
(_PAGE_CACHE_MODE_WC) (the pointer newtype points to the variable "pcm" in
the function reserve_pfn_range)
Then, we go back to reserve_pfn_range, the variable want_pcm is 2 and the
variable pcm is 1. reserve_pfn_range checks "if (pcm != want_pcm)", prints
a warning "x86/PAT: Xorg:3986 map pfn expected mapping type uncached-minus
for [mem 0xe4000000-0xe5ffffff], got write-combining", returns an error -
and this causes fork failure.
> Bug 2: arch_phys_wc_add() appears to be checking the wrong condition.
> How about checking the right condition? It doesn't actually want to
> know if PAT is enabled -- it wants to know if the PAT contains a
> usable WC entry. Something like pat_has_wc() would be better, I
> think.
>
> --Andy
The function pat_init() always programs the PAT with the WC type. So -
surely we can rename pat_enabled() to pat_has_wc(). But renaming the
function doesn't change functionality.
This is the same patch with pat_enabled() renamed to pat_has_wc(). Note
also that this renaming causes conflicts when backporting the patch to
stable kernels.
Mikulas
X86: don't report PAT on CPUs that don't support it
In the file arch/x86/mm/pat.c, there's a variable __pat_enabled. The
variable is set to 1 by default and the function pat_init() sets
__pat_enabled to 0 if the CPU doesn't support PAT.
However, on AMD K6-3 CPU, the processor initialization code never calls
pat_init() and so __pat_enabled stays 1 and the function pat_enabled()
returns true, even though the K6-3 CPU doesn't support PAT.
The result of this bug is that this warning is produced when attemting to
start the Xserver and the Xserver doesn't start (fork() returns ENOMEM).
Another symptom of this bug is that the framebuffer driver doesn't set the
K6-3 MTRR registers.
This patch changes pat_enabled() so that it returns true only if pat
initialization was actually done.
As Andy Lutomirski suggested, we also need to call init_cache_modes() if
pat was not initialized, so we call it after mtrr_bp_init()
(mtrr_bp_init() would or wouldn't call pat_init()). Note that
init_cache_modes() detects if it was called more than once and does
nothing in that case.
x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3891 at arch/x86/mm/pat.c:1020 untrack_pfn+0x5c/0x9f
Modules linked in: blowfish_generic blowfish_common cbc dm_crypt dm_loop msr configfs cpufreq_userspace cpufreq_powersave cpufreq_ondemand cpufreq_conservative ext4 crc16 jbd2 mbcache hpfs nls_cp852 msdos fat matroxfb_base matroxfb_g450 matroxfb_accel cfbfillrect cfbimgblt cfbcopyarea matroxfb_DAC1064 g450_pll matroxfb_misc floppy snd_usb_audio snd_hwdep snd_usbmidi_lib snd_seq_midi snd_seq_midi_event snd_rawmidi snd_pcm snd_seq snd_seq_device snd_timer hid_generic snd usbhid hid soundcore powernow_k6 pcspkr evdev e1000 ehci_pci uhci_hcd ehci_hcd usbcore usb_common dm_mod pata_it821x unix
CPU: 0 PID: 3891 Comm: Xorg Not tainted 4.11.0-rc6-test+ #35
Hardware name: System Manufacturer Product Name/VA-503A, BIOS 4.51 PG 08/02/00
Call Trace:
? __warn+0xab/0xc0
? untrack_pfn+0x5c/0x9f
? warn_slowpath_null+0xf/0x13
? untrack_pfn+0x5c/0x9f
? unmap_single_vma+0x43/0x66
? unmap_vmas+0x24/0x30
? exit_mmap+0x3c/0xa5
? __mmput+0xf/0x76
? copy_process.part.76+0xb43/0x1129
? _do_fork+0x96/0x177
? do_int80_syscall_32+0x3e/0x4c
? entry_INT80_32+0x2a/0x2a
---[ end trace 8726f9d9fa90d702 ]---
x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining
Signed-off-by: Mikulas Patocka <[email protected]>
Cc: [email protected] # v4.2+
---
arch/x86/include/asm/pat.h | 3 ++-
arch/x86/include/asm/pci.h | 2 +-
arch/x86/kernel/cpu/mtrr/main.c | 2 +-
arch/x86/kernel/setup.c | 2 ++
arch/x86/mm/iomap_32.c | 2 +-
arch/x86/mm/ioremap.c | 2 +-
arch/x86/mm/pat.c | 28 +++++++++++++++-------------
drivers/infiniband/hw/mlx5/main.c | 2 +-
drivers/media/pci/ivtv/ivtvfb.c | 2 +-
9 files changed, 25 insertions(+), 20 deletions(-)
Index: linux-stable/arch/x86/mm/pat.c
===================================================================
--- linux-stable.orig/arch/x86/mm/pat.c
+++ linux-stable/arch/x86/mm/pat.c
@@ -40,7 +40,6 @@
static bool boot_cpu_done;
static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);
-static void init_cache_modes(void);
void pat_disable(const char *reason)
{
@@ -65,11 +64,13 @@ static int __init nopat(char *str)
}
early_param("nopat", nopat);
-bool pat_enabled(void)
+static bool __read_mostly __pat_has_wc = false;
+
+bool pat_has_wc(void)
{
- return !!__pat_enabled;
+ return __pat_has_wc;
}
-EXPORT_SYMBOL_GPL(pat_enabled);
+EXPORT_SYMBOL_GPL(pat_has_wc);
int pat_debug_enable;
@@ -225,6 +226,7 @@ static void pat_bsp_init(u64 pat)
}
wrmsrl(MSR_IA32_CR_PAT, pat);
+ __pat_has_wc = true;
__init_cache_modes(pat);
}
@@ -242,7 +244,7 @@ static void pat_ap_init(u64 pat)
wrmsrl(MSR_IA32_CR_PAT, pat);
}
-static void init_cache_modes(void)
+void init_cache_modes(void)
{
u64 pat = 0;
static int init_cm_done;
@@ -306,7 +308,7 @@ void pat_init(void)
u64 pat;
struct cpuinfo_x86 *c = &boot_cpu_data;
- if (!pat_enabled()) {
+ if (!__pat_enabled) {
init_cache_modes();
return;
}
@@ -539,7 +541,7 @@ int reserve_memtype(u64 start, u64 end,
BUG_ON(start >= end); /* end is exclusive */
- if (!pat_enabled()) {
+ if (!pat_has_wc()) {
/* This is identical to page table setting without PAT */
if (new_type)
*new_type = req_type;
@@ -610,7 +612,7 @@ int free_memtype(u64 start, u64 end)
int is_range_ram;
struct memtype *entry;
- if (!pat_enabled())
+ if (!pat_has_wc())
return 0;
/* Low ISA region is always mapped WB. No need to track */
@@ -765,7 +767,7 @@ static inline int range_is_allowed(unsig
u64 to = from + size;
u64 cursor = from;
- if (!pat_enabled())
+ if (!pat_has_wc())
return 1;
while (cursor < to) {
@@ -848,7 +850,7 @@ static int reserve_pfn_range(u64 paddr,
* the type requested matches the type of first page in the range.
*/
if (is_ram) {
- if (!pat_enabled())
+ if (!pat_has_wc())
return 0;
pcm = lookup_memtype(paddr);
@@ -964,7 +966,7 @@ int track_pfn_remap(struct vm_area_struc
return ret;
}
- if (!pat_enabled())
+ if (!pat_has_wc())
return 0;
/*
@@ -991,7 +993,7 @@ void track_pfn_insert(struct vm_area_str
{
enum page_cache_mode pcm;
- if (!pat_enabled())
+ if (!pat_has_wc())
return;
/* Set prot based on lookup */
@@ -1128,7 +1130,7 @@ static const struct file_operations memt
static int __init pat_memtype_list_init(void)
{
- if (pat_enabled()) {
+ if (pat_has_wc()) {
debugfs_create_file("pat_memtype_list", S_IRUSR,
arch_debugfs_dir, NULL, &memtype_fops);
}
Index: linux-stable/arch/x86/include/asm/pat.h
===================================================================
--- linux-stable.orig/arch/x86/include/asm/pat.h
+++ linux-stable/arch/x86/include/asm/pat.h
@@ -4,9 +4,10 @@
#include <linux/types.h>
#include <asm/pgtable_types.h>
-bool pat_enabled(void);
+bool pat_has_wc(void);
void pat_disable(const char *reason);
extern void pat_init(void);
+extern void init_cache_modes(void);
extern int reserve_memtype(u64 start, u64 end,
enum page_cache_mode req_pcm, enum page_cache_mode *ret_pcm);
Index: linux-stable/arch/x86/kernel/setup.c
===================================================================
--- linux-stable.orig/arch/x86/kernel/setup.c
+++ linux-stable/arch/x86/kernel/setup.c
@@ -1070,6 +1070,8 @@ void __init setup_arch(char **cmdline_p)
/* update e820 for memory not covered by WB MTRRs */
mtrr_bp_init();
+ if (!pat_has_wc())
+ init_cache_modes();
if (mtrr_trim_uncached_memory(max_pfn))
max_pfn = e820__end_of_ram_pfn();
Index: linux-stable/arch/x86/include/asm/pci.h
===================================================================
--- linux-stable.orig/arch/x86/include/asm/pci.h
+++ linux-stable/arch/x86/include/asm/pci.h
@@ -103,7 +103,7 @@ int pcibios_set_irq_routing(struct pci_d
#define HAVE_PCI_MMAP
-#define arch_can_pci_mmap_wc() pat_enabled()
+#define arch_can_pci_mmap_wc() pat_has_wc()
#define ARCH_GENERIC_PCI_MMAP_RESOURCE
#ifdef CONFIG_PCI
Index: linux-stable/arch/x86/kernel/cpu/mtrr/main.c
===================================================================
--- linux-stable.orig/arch/x86/kernel/cpu/mtrr/main.c
+++ linux-stable/arch/x86/kernel/cpu/mtrr/main.c
@@ -556,7 +556,7 @@ int arch_phys_wc_add(unsigned long base,
{
int ret;
- if (pat_enabled() || !mtrr_enabled())
+ if (pat_has_wc() || !mtrr_enabled())
return 0; /* Success! (We don't need to do anything.) */
ret = mtrr_add(base, size, MTRR_TYPE_WRCOMB, true);
Index: linux-stable/arch/x86/mm/iomap_32.c
===================================================================
--- linux-stable.orig/arch/x86/mm/iomap_32.c
+++ linux-stable/arch/x86/mm/iomap_32.c
@@ -84,7 +84,7 @@ iomap_atomic_prot_pfn(unsigned long pfn,
* is UC or WC. UC- gets the real intention, of the user, which is
* "WC if the MTRR is WC, UC if you can't do that."
*/
- if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
+ if (!pat_has_wc() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
prot = __pgprot(__PAGE_KERNEL |
cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
Index: linux-stable/arch/x86/mm/ioremap.c
===================================================================
--- linux-stable.orig/arch/x86/mm/ioremap.c
+++ linux-stable/arch/x86/mm/ioremap.c
@@ -230,7 +230,7 @@ void __iomem *ioremap_nocache(resource_s
{
/*
* Ideally, this should be:
- * pat_enabled() ? _PAGE_CACHE_MODE_UC : _PAGE_CACHE_MODE_UC_MINUS;
+ * pat_has_wc() ? _PAGE_CACHE_MODE_UC : _PAGE_CACHE_MODE_UC_MINUS;
*
* Till we fix all X drivers to use ioremap_wc(), we will use
* UC MINUS. Drivers that are certain they need or can already
Index: linux-stable/drivers/infiniband/hw/mlx5/main.c
===================================================================
--- linux-stable.orig/drivers/infiniband/hw/mlx5/main.c
+++ linux-stable/drivers/infiniband/hw/mlx5/main.c
@@ -1602,7 +1602,7 @@ static int uar_mmap(struct mlx5_ib_dev *
case MLX5_IB_MMAP_WC_PAGE:
/* Some architectures don't support WC memory */
#if defined(CONFIG_X86)
- if (!pat_enabled())
+ if (!pat_has_wc())
return -EPERM;
#elif !(defined(CONFIG_PPC) || (defined(CONFIG_ARM) && defined(CONFIG_MMU)))
return -EPERM;
Index: linux-stable/drivers/media/pci/ivtv/ivtvfb.c
===================================================================
--- linux-stable.orig/drivers/media/pci/ivtv/ivtvfb.c
+++ linux-stable/drivers/media/pci/ivtv/ivtvfb.c
@@ -1168,7 +1168,7 @@ static int ivtvfb_init_card(struct ivtv
int rc;
#ifdef CONFIG_X86_64
- if (pat_enabled()) {
+ if (pat_has_wc()) {
pr_warn("ivtvfb needs PAT disabled, boot with nopat kernel parameter\n");
return -ENODEV;
}
On Tue, 6 Jun 2017, Mikulas Patocka wrote:
> Hi
>
> Here I send the second version of the patch. It drops the change from
> boot_cpu_has(X86_FEATURE_PAT) to this_cpu_has(X86_FEATURE_PAT) (that
> caused kernel to be unbootable for some people).
>
> Another change is that setup_arch() calls init_cache_modes() if PAT is
> disabled, so that init_cache_modes() is always called.
>
> Mikulas
Is there any progress with this patch? Will you accept it or do you want
some changes to it?
> From: Mikulas Patocka <[email protected]>
>
> In the file arch/x86/mm/pat.c, there's a variable __pat_enabled. The
> variable is set to 1 by default and the function pat_init() sets
> __pat_enabled to 0 if the CPU doesn't support PAT.
>
> However, on AMD K6-3 CPU, the processor initialization code never calls
> pat_init() and so __pat_enabled stays 1 and the function pat_enabled()
> returns true, even though the K6-3 CPU doesn't support PAT.
>
> The result of this bug is that this warning is produced when attemting to
> start the Xserver and the Xserver doesn't start (fork() returns ENOMEM).
> Another symptom of this bug is that the framebuffer driver doesn't set the
> K6-3 MTRR registers.
>
> This patch changes pat_enabled() so that it returns true only if pat
> initialization was actually done.
>
> As Andy Lutomirski suggested, we also need to call init_cache_modes() if
> pat was not initialized, so we call it after mtrr_bp_init()
> (mtrr_bp_init() would or wouldn't call pat_init()). Note that
> init_cache_modes() detects if it was called more than once and does
> nothing in that case.
>
> x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 3891 at arch/x86/mm/pat.c:1020 untrack_pfn+0x5c/0x9f
> Modules linked in: blowfish_generic blowfish_common cbc dm_crypt dm_loop msr configfs cpufreq_userspace cpufreq_powersave cpufreq_ondemand cpufreq_conservative ext4 crc16 jbd2 mbcache hpfs nls_cp852 msdos fat matroxfb_base matroxfb_g450 matroxfb_accel cfbfillrect cfbimgblt cfbcopyarea matroxfb_DAC1064 g450_pll matroxfb_misc floppy snd_usb_audio snd_hwdep snd_usbmidi_lib snd_seq_midi snd_seq_midi_event snd_rawmidi snd_pcm snd_seq snd_seq_device snd_timer hid_generic snd usbhid hid soundcore powernow_k6 pcspkr evdev e1000 ehci_pci uhci_hcd ehci_hcd usbcore usb_common dm_mod pata_it821x unix
> CPU: 0 PID: 3891 Comm: Xorg Not tainted 4.11.0-rc6-test+ #35
> Hardware name: System Manufacturer Product Name/VA-503A, BIOS 4.51 PG 08/02/00
> Call Trace:
> ? __warn+0xab/0xc0
> ? untrack_pfn+0x5c/0x9f
> ? warn_slowpath_null+0xf/0x13
> ? untrack_pfn+0x5c/0x9f
> ? unmap_single_vma+0x43/0x66
> ? unmap_vmas+0x24/0x30
> ? exit_mmap+0x3c/0xa5
> ? __mmput+0xf/0x76
> ? copy_process.part.76+0xb43/0x1129
> ? _do_fork+0x96/0x177
> ? do_int80_syscall_32+0x3e/0x4c
> ? entry_INT80_32+0x2a/0x2a
> ---[ end trace 8726f9d9fa90d702 ]---
> x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining
>
> Signed-off-by: Mikulas Patocka <[email protected]>
> Cc: [email protected] # v4.2+
>
> ---
> arch/x86/include/asm/pat.h | 1 +
> arch/x86/kernel/setup.c | 2 ++
> arch/x86/mm/pat.c | 10 ++++++----
> 3 files changed, 9 insertions(+), 4 deletions(-)
>
> Index: linux-stable/arch/x86/mm/pat.c
> ===================================================================
> --- linux-stable.orig/arch/x86/mm/pat.c
> +++ linux-stable/arch/x86/mm/pat.c
> @@ -40,7 +40,6 @@
> static bool boot_cpu_done;
>
> static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);
> -static void init_cache_modes(void);
>
> void pat_disable(const char *reason)
> {
> @@ -65,9 +64,11 @@ static int __init nopat(char *str)
> }
> early_param("nopat", nopat);
>
> +static bool __read_mostly __pat_initialized = false;
> +
> bool pat_enabled(void)
> {
> - return !!__pat_enabled;
> + return __pat_initialized;
> }
> EXPORT_SYMBOL_GPL(pat_enabled);
>
> @@ -225,6 +226,7 @@ static void pat_bsp_init(u64 pat)
> }
>
> wrmsrl(MSR_IA32_CR_PAT, pat);
> + __pat_initialized = true;
>
> __init_cache_modes(pat);
> }
> @@ -242,7 +244,7 @@ static void pat_ap_init(u64 pat)
> wrmsrl(MSR_IA32_CR_PAT, pat);
> }
>
> -static void init_cache_modes(void)
> +void init_cache_modes(void)
> {
> u64 pat = 0;
> static int init_cm_done;
> @@ -306,7 +308,7 @@ void pat_init(void)
> u64 pat;
> struct cpuinfo_x86 *c = &boot_cpu_data;
>
> - if (!pat_enabled()) {
> + if (!__pat_enabled) {
> init_cache_modes();
> return;
> }
> Index: linux-stable/arch/x86/include/asm/pat.h
> ===================================================================
> --- linux-stable.orig/arch/x86/include/asm/pat.h
> +++ linux-stable/arch/x86/include/asm/pat.h
> @@ -7,6 +7,7 @@
> bool pat_enabled(void);
> void pat_disable(const char *reason);
> extern void pat_init(void);
> +extern void init_cache_modes(void);
>
> extern int reserve_memtype(u64 start, u64 end,
> enum page_cache_mode req_pcm, enum page_cache_mode *ret_pcm);
> Index: linux-stable/arch/x86/kernel/setup.c
> ===================================================================
> --- linux-stable.orig/arch/x86/kernel/setup.c
> +++ linux-stable/arch/x86/kernel/setup.c
> @@ -1070,6 +1070,8 @@ void __init setup_arch(char **cmdline_p)
>
> /* update e820 for memory not covered by WB MTRRs */
> mtrr_bp_init();
> + if (!pat_enabled())
> + init_cache_modes();
> if (mtrr_trim_uncached_memory(max_pfn))
> max_pfn = e820__end_of_ram_pfn();
>
>
On Mon, 3 Jul 2017, Mikulas Patocka wrote:
> Is there any progress with this patch? Will you accept it or do you want
> some changes to it?
Aside of the unparseable changelog, that patch is mostly duct tape.
1) __pat_enabled should be renamed to pat_disabled, as that is the actual
purpose of that variable
2) Making the call to init_cache_modes() conditional in setup_arch() is
pointless. init_cache_modes() has it's own protection against multiple
invocations.
3) It adds yet another invocation of init_cache_modes() instead of getting
rid of the ones in pat_disable() and the pat disabled case in pat_init().
I've reworked the whole thing into the patch below.
Thanks,
tglx
8<---------------------
Subject: x86/mm/pat: Don't report PAT on CPUs that don't support it
From: Mikulas Patocka <[email protected]>
Date: Tue, 6 Jun 2017 18:49:39 -0400 (EDT)
The pat_enabled() logic is broken on CPUs which do not support PAT and
where the initialization code fails to call pat_init(). Due to that the
enabled flag stays true and pat_enabled() returns true wrongfully.
As a consequence the mappings, e.g. for Xorg, are set up with the wrong
caching mode and the required MTRR setups are omitted.
To cure this the following changes are required:
1) Make pat_enabled() return true only if PAT initialization was
invoked and successful.
2) Invoke init_cache_modes() unconditionally in setup_arch() and
remove the extra callsites in pat_disable() and the pat disabled
code path in pat_init().
Also rename __pat_enabled to pat_disabled to reflect the real purpose of
this variable.
Signed-off-by: Mikulas Patocka <[email protected]>
Cc: Bernhard Held <[email protected]>
Cc: Toshi Kani <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: "Luis R. Rodriguez" <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
---
arch/x86/include/asm/pat.h | 1 +
arch/x86/kernel/setup.c | 7 +++++++
arch/x86/mm/pat.c | 22 +++++++++-------------
3 files changed, 17 insertions(+), 13 deletions(-)
--- a/arch/x86/include/asm/pat.h
+++ b/arch/x86/include/asm/pat.h
@@ -7,6 +7,7 @@
bool pat_enabled(void);
void pat_disable(const char *reason);
extern void pat_init(void);
+extern void init_cache_modes(void);
extern int reserve_memtype(u64 start, u64 end,
enum page_cache_mode req_pcm, enum page_cache_mode *ret_pcm);
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1076,6 +1076,13 @@ void __init setup_arch(char **cmdline_p)
max_possible_pfn = max_pfn;
/*
+ * This call is required when the CPU does not support PAT. If
+ * mtrr_bp_init() invoked it already via pat_init() the call has no
+ * effect.
+ */
+ init_cache_modes();
+
+ /*
* Define random base addresses for memory sections after max_pfn is
* defined and before each memory section base is used.
*/
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -37,14 +37,13 @@
#undef pr_fmt
#define pr_fmt(fmt) "" fmt
-static bool boot_cpu_done;
-
-static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);
-static void init_cache_modes(void);
+static bool __read_mostly boot_cpu_done;
+static bool __read_mostly pat_disabled = !IS_ENABLED(CONFIG_X86_PAT);
+static bool __read_mostly pat_initialized;
void pat_disable(const char *reason)
{
- if (!__pat_enabled)
+ if (pat_disabled)
return;
if (boot_cpu_done) {
@@ -52,10 +51,8 @@ void pat_disable(const char *reason)
return;
}
- __pat_enabled = 0;
+ pat_disabled = true;
pr_info("x86/PAT: %s\n", reason);
-
- init_cache_modes();
}
static int __init nopat(char *str)
@@ -67,7 +64,7 @@ early_param("nopat", nopat);
bool pat_enabled(void)
{
- return !!__pat_enabled;
+ return pat_initialized;
}
EXPORT_SYMBOL_GPL(pat_enabled);
@@ -225,6 +222,7 @@ static void pat_bsp_init(u64 pat)
}
wrmsrl(MSR_IA32_CR_PAT, pat);
+ __pat_initialized = true;
__init_cache_modes(pat);
}
@@ -242,7 +240,7 @@ static void pat_ap_init(u64 pat)
wrmsrl(MSR_IA32_CR_PAT, pat);
}
-static void init_cache_modes(void)
+void init_cache_modes(void)
{
u64 pat = 0;
static int init_cm_done;
@@ -306,10 +304,8 @@ void pat_init(void)
u64 pat;
struct cpuinfo_x86 *c = &boot_cpu_data;
- if (!pat_enabled()) {
- init_cache_modes();
+ if (pat_disabled)
return;
- }
if ((c->x86_vendor == X86_VENDOR_INTEL) &&
(((c->x86 == 0x6) && (c->x86_model <= 0xd)) ||
On Tue, 4 Jul 2017, Thomas Gleixner wrote:
> wrmsrl(MSR_IA32_CR_PAT, pat);
> + __pat_initialized = true;
That should be
> + pat_initialized = true;
of course.
On Tue, 4 Jul 2017, Thomas Gleixner wrote:
> On Mon, 3 Jul 2017, Mikulas Patocka wrote:
> > Is there any progress with this patch? Will you accept it or do you want
> > some changes to it?
>
> Aside of the unparseable changelog, that patch is mostly duct tape.
>
> 1) __pat_enabled should be renamed to pat_disabled, as that is the actual
> purpose of that variable
>
> 2) Making the call to init_cache_modes() conditional in setup_arch() is
> pointless. init_cache_modes() has it's own protection against multiple
> invocations.
>
> 3) It adds yet another invocation of init_cache_modes() instead of getting
> rid of the ones in pat_disable() and the pat disabled case in pat_init().
>
> I've reworked the whole thing into the patch below.
>
> Thanks,
>
> tglx
Yes - renaming __pat_enabled to pat_disabled is a good thing.
Just one more change - init_cache_modes() is protected against multiple
calls, but pat_bsp_init() calls __init_cache_modes() (not
init_cacha_modes()). The generic code would call init_cache_modes() later
and init_cache_modes() would do the initialization again - it would be
mostly harmless because it would just read the pat MSR that pat_bsp_init
have written and call __init_cache_modes() with the same value - the
symptom is that on machines with PAT we see this line twice in the syslog:
[ 0.000000] x86/PAT: Configuration [0-7]: WB WC UC- UC WB WC UC- WT
[ 0.000000] x86/PAT: Configuration [0-7]: WB WC UC- UC WB WC UC- WT
I fixed this double initialization by moving the variable init_cm_done to
file scope and setting it in __init_cache_modes().
Mikulas
8<---------------------
Subject: x86/mm/pat: Don't report PAT on CPUs that don't support it
From: Mikulas Patocka <[email protected]>
Date: Tue, 6 Jun 2017 18:49:39 -0400 (EDT)
The pat_enabled() logic is broken on CPUs which do not support PAT and
where the initialization code fails to call pat_init(). Due to that the
enabled flag stays true and pat_enabled() returns true wrongfully.
As a consequence the mappings, e.g. for Xorg, are set up with the wrong
caching mode and the required MTRR setups are omitted.
To cure this the following changes are required:
1) Make pat_enabled() return true only if PAT initialization was
invoked and successful.
2) Invoke init_cache_modes() unconditionally in setup_arch() and
remove the extra callsites in pat_disable() and the pat disabled
code path in pat_init().
Also rename __pat_enabled to pat_disabled to reflect the real purpose of
this variable.
Signed-off-by: Mikulas Patocka <[email protected]>
Cc: Bernhard Held <[email protected]>
Cc: Toshi Kani <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: "Luis R. Rodriguez" <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: [email protected] # v4.2+
---
arch/x86/include/asm/pat.h | 1 +
arch/x86/kernel/setup.c | 7 +++++++
arch/x86/mm/pat.c | 28 ++++++++++++----------------
3 files changed, 20 insertions(+), 16 deletions(-)
Index: linux-2.6/arch/x86/include/asm/pat.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/pat.h
+++ linux-2.6/arch/x86/include/asm/pat.h
@@ -7,6 +7,7 @@
bool pat_enabled(void);
void pat_disable(const char *reason);
extern void pat_init(void);
+extern void init_cache_modes(void);
extern int reserve_memtype(u64 start, u64 end,
enum page_cache_mode req_pcm, enum page_cache_mode *ret_pcm);
Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -1076,6 +1076,13 @@ void __init setup_arch(char **cmdline_p)
max_possible_pfn = max_pfn;
/*
+ * This call is required when the CPU does not support PAT. If
+ * mtrr_bp_init() invoked it already via pat_init() the call has no
+ * effect.
+ */
+ init_cache_modes();
+
+ /*
* Define random base addresses for memory sections after max_pfn is
* defined and before each memory section base is used.
*/
Index: linux-2.6/arch/x86/mm/pat.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/pat.c
+++ linux-2.6/arch/x86/mm/pat.c
@@ -37,14 +37,14 @@
#undef pr_fmt
#define pr_fmt(fmt) "" fmt
-static bool boot_cpu_done;
-
-static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);
-static void init_cache_modes(void);
+static bool __read_mostly boot_cpu_done;
+static bool __read_mostly pat_disabled = !IS_ENABLED(CONFIG_X86_PAT);
+static bool __read_mostly pat_initialized;
+static bool __read_mostly init_cm_done;
void pat_disable(const char *reason)
{
- if (!__pat_enabled)
+ if (pat_disabled)
return;
if (boot_cpu_done) {
@@ -52,10 +52,8 @@ void pat_disable(const char *reason)
return;
}
- __pat_enabled = 0;
+ pat_disabled = true;
pr_info("x86/PAT: %s\n", reason);
-
- init_cache_modes();
}
static int __init nopat(char *str)
@@ -67,7 +65,7 @@ early_param("nopat", nopat);
bool pat_enabled(void)
{
- return !!__pat_enabled;
+ return pat_initialized;
}
EXPORT_SYMBOL_GPL(pat_enabled);
@@ -205,6 +203,8 @@ static void __init_cache_modes(u64 pat)
update_cache_mode_entry(i, cache);
}
pr_info("x86/PAT: Configuration [0-7]: %s\n", pat_msg);
+
+ init_cm_done = true;
}
#define PAT(x, y) ((u64)PAT_ ## y << ((x)*8))
@@ -225,6 +225,7 @@ static void pat_bsp_init(u64 pat)
}
wrmsrl(MSR_IA32_CR_PAT, pat);
+ pat_initialized = true;
__init_cache_modes(pat);
}
@@ -242,10 +243,9 @@ static void pat_ap_init(u64 pat)
wrmsrl(MSR_IA32_CR_PAT, pat);
}
-static void init_cache_modes(void)
+void init_cache_modes(void)
{
u64 pat = 0;
- static int init_cm_done;
if (init_cm_done)
return;
@@ -287,8 +287,6 @@ static void init_cache_modes(void)
}
__init_cache_modes(pat);
-
- init_cm_done = 1;
}
/**
@@ -306,10 +304,8 @@ void pat_init(void)
u64 pat;
struct cpuinfo_x86 *c = &boot_cpu_data;
- if (!pat_enabled()) {
- init_cache_modes();
+ if (pat_disabled)
return;
- }
if ((c->x86_vendor == X86_VENDOR_INTEL) &&
(((c->x86 == 0x6) && (c->x86_model <= 0xd)) ||
Commit-ID: 99c13b8c8896d7bcb92753bf0c63a8de4326e78d
Gitweb: http://git.kernel.org/tip/99c13b8c8896d7bcb92753bf0c63a8de4326e78d
Author: Mikulas Patocka <[email protected]>
AuthorDate: Tue, 4 Jul 2017 19:04:23 -0400
Committer: Thomas Gleixner <[email protected]>
CommitDate: Wed, 5 Jul 2017 09:01:24 +0200
x86/mm/pat: Don't report PAT on CPUs that don't support it
The pat_enabled() logic is broken on CPUs which do not support PAT and
where the initialization code fails to call pat_init(). Due to that the
enabled flag stays true and pat_enabled() returns true wrongfully.
As a consequence the mappings, e.g. for Xorg, are set up with the wrong
caching mode and the required MTRR setups are omitted.
To cure this the following changes are required:
1) Make pat_enabled() return true only if PAT initialization was
invoked and successful.
2) Invoke init_cache_modes() unconditionally in setup_arch() and
remove the extra callsites in pat_disable() and the pat disabled
code path in pat_init().
Also rename __pat_enabled to pat_disabled to reflect the real purpose of
this variable.
Fixes: 9cd25aac1f44 ("x86/mm/pat: Emulate PAT when it is disabled")
Signed-off-by: Mikulas Patocka <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Bernhard Held <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: "Luis R. Rodriguez" <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1707041749300.3456@file01.intranet.prod.int.rdu2.redhat.com
---
arch/x86/include/asm/pat.h | 1 +
arch/x86/kernel/setup.c | 7 +++++++
arch/x86/mm/pat.c | 28 ++++++++++++----------------
3 files changed, 20 insertions(+), 16 deletions(-)
diff --git a/arch/x86/include/asm/pat.h b/arch/x86/include/asm/pat.h
index 0b1ff4c..fffb279 100644
--- a/arch/x86/include/asm/pat.h
+++ b/arch/x86/include/asm/pat.h
@@ -7,6 +7,7 @@
bool pat_enabled(void);
void pat_disable(const char *reason);
extern void pat_init(void);
+extern void init_cache_modes(void);
extern int reserve_memtype(u64 start, u64 end,
enum page_cache_mode req_pcm, enum page_cache_mode *ret_pcm);
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 65622f0..3486d04 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1076,6 +1076,13 @@ void __init setup_arch(char **cmdline_p)
max_possible_pfn = max_pfn;
/*
+ * This call is required when the CPU does not support PAT. If
+ * mtrr_bp_init() invoked it already via pat_init() the call has no
+ * effect.
+ */
+ init_cache_modes();
+
+ /*
* Define random base addresses for memory sections after max_pfn is
* defined and before each memory section base is used.
*/
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 9b78685..4597950 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -37,14 +37,14 @@
#undef pr_fmt
#define pr_fmt(fmt) "" fmt
-static bool boot_cpu_done;
-
-static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);
-static void init_cache_modes(void);
+static bool __read_mostly boot_cpu_done;
+static bool __read_mostly pat_disabled = !IS_ENABLED(CONFIG_X86_PAT);
+static bool __read_mostly pat_initialized;
+static bool __read_mostly init_cm_done;
void pat_disable(const char *reason)
{
- if (!__pat_enabled)
+ if (pat_disabled)
return;
if (boot_cpu_done) {
@@ -52,10 +52,8 @@ void pat_disable(const char *reason)
return;
}
- __pat_enabled = 0;
+ pat_disabled = true;
pr_info("x86/PAT: %s\n", reason);
-
- init_cache_modes();
}
static int __init nopat(char *str)
@@ -67,7 +65,7 @@ early_param("nopat", nopat);
bool pat_enabled(void)
{
- return !!__pat_enabled;
+ return pat_initialized;
}
EXPORT_SYMBOL_GPL(pat_enabled);
@@ -205,6 +203,8 @@ static void __init_cache_modes(u64 pat)
update_cache_mode_entry(i, cache);
}
pr_info("x86/PAT: Configuration [0-7]: %s\n", pat_msg);
+
+ init_cm_done = true;
}
#define PAT(x, y) ((u64)PAT_ ## y << ((x)*8))
@@ -225,6 +225,7 @@ static void pat_bsp_init(u64 pat)
}
wrmsrl(MSR_IA32_CR_PAT, pat);
+ pat_initialized = true;
__init_cache_modes(pat);
}
@@ -242,10 +243,9 @@ static void pat_ap_init(u64 pat)
wrmsrl(MSR_IA32_CR_PAT, pat);
}
-static void init_cache_modes(void)
+void init_cache_modes(void)
{
u64 pat = 0;
- static int init_cm_done;
if (init_cm_done)
return;
@@ -287,8 +287,6 @@ static void init_cache_modes(void)
}
__init_cache_modes(pat);
-
- init_cm_done = 1;
}
/**
@@ -306,10 +304,8 @@ void pat_init(void)
u64 pat;
struct cpuinfo_x86 *c = &boot_cpu_data;
- if (!pat_enabled()) {
- init_cache_modes();
+ if (pat_disabled)
return;
- }
if ((c->x86_vendor == X86_VENDOR_INTEL) &&
(((c->x86 == 0x6) && (c->x86_model <= 0xd)) ||