linux-stable.git/arch/mips/kernel/cpu-probe.c, branch linux-5.15.y

MIPS: Always record SEGBITS in cpu_data.vmbits

2026-06-01T15:35:03+00:00

commit 8374c2cb83b95b3c92f129fd56527225c20a058c upstream.

With a 32-bit kernel running on 64-bit MIPS hardware the hardcoded value
of `cpu_vmbits' only records the size of compatibility useg and does not
reflect the size of native xuseg or the complete range of values allowed
in the VPN2 field of TLB entries.

An upcoming change will need the actual VPN2 value range permitted even
in 32-bit kernel configurations, so always include the `vmbits' member
in `struct cpuinfo_mips' and probe for SEGBITS when running on 64-bit
hardware and resorting to the currently hardcoded value of 31 on 32-bit
processors.  No functional change for users of `cpu_vmbits'.

Signed-off-by: Maciej W. Rozycki 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

MIPS: Loongson64: Set timer mode in cpu-probe

2024-09-04T11:23:35+00:00

commit 1cb6ab446424649f03c82334634360c2e3043684 upstream.

Loongson64 C and G processors have EXTIMER feature which
is conflicting with CP0 counter.

Although the processor resets in EXTIMER disabled & INTIMER
enabled mode, which is compatible with MIPS CP0 compare, firmware
may attempt to enable EXTIMER and interfere CP0 compare.

Set timer mode back to MIPS compatible mode to fix booting on
systems with such firmware before we have an actual driver for
EXTIMER.

Cc: stable@vger.kernel.org
Signed-off-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Greg Kroah-Hartman

MIPS: Loongson: Fix cpu_probe_loongson() again

2023-07-23T11:47:48+00:00

commit 65fee014dc41a774bcd94896f3fb380bc39d8dda upstream.

Commit 7db5e9e9e5e6c10d7d ("MIPS: loongson64: fix FTLB configuration")
move decode_configs() from the beginning of cpu_probe_loongson() to the
end in order to fix FTLB configuration. However, it breaks the CPUCFG
decoding because decode_configs() use "c->options = xxxx" rather than
"c->options |= xxxx", all information get from CPUCFG by decode_cpucfg()
is lost.

This causes error when creating a KVM guest on Loongson-3A4000:
Exception Code: 4 not handled @ PC: 0000000087ad5981, inst: 0xcb7a1898 BadVaddr: 0x0 Status: 0x0

Fix this by moving the c->cputype setting to the beginning and moving
decode_configs() after that.

Fixes: 7db5e9e9e5e6c10d7d ("MIPS: loongson64: fix FTLB configuration")
Cc: stable@vger.kernel.org
Cc: Huang Pei 
Signed-off-by: Huacai Chen 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Greg Kroah-Hartman

MIPS: loongson64: fix FTLB configuration

2021-12-01T08:04:52+00:00

[ Upstream commit 7db5e9e9e5e6c10d7d26f8df7f8fd8841cb15ee7 ]

It turns out that 'decode_configs' -> 'set_ftlb_enable' is called under
c->cputype unset, which leaves FTLB disabled on BOTH 3A2000 and 3A3000

Fix it by calling "decode_configs" after c->cputype is initialized

Fixes: da1bd29742b1 ("MIPS: Loongson64: Probe CPU features via CPUCFG")
Signed-off-by: Huang Pei 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Sasha Levin

MIPS: cpu-probe: Fix FPU detection on Ingenic JZ4760(B)

2021-06-01T09:44:47+00:00

Ingenic JZ4760 and JZ4760B do have a FPU, but the config registers don't
report it. Force the FPU detection in case the processor ID match the
JZ4760(B) one.

Signed-off-by: Paul Cercueil 
Signed-off-by: Thomas Bogendoerfer

MIPS: Loongson64: Use _CACHE_UNCACHED instead of _CACHE_UNCACHED_ACCELERATED

2021-04-06T13:12:58+00:00

Loongson64 processors have a writecombine issue that maybe failed to
write back framebuffer used with ATI Radeon or AMD GPU at times, after
commit 8a08e50cee66 ("drm: Permit video-buffers writecombine mapping
for MIPS"), there exists some errors such as blurred screen and lockup,
and so on.

[   60.958721] radeon 0000:03:00.0: ring 0 stalled for more than 10079msec
[   60.965315] radeon 0000:03:00.0: GPU lockup (current fence id 0x0000000000000112 last fence id 0x000000000000011d on ring 0)
[   60.976525] radeon 0000:03:00.0: ring 3 stalled for more than 10086msec
[   60.983156] radeon 0000:03:00.0: GPU lockup (current fence id 0x0000000000000374 last fence id 0x00000000000003a8 on ring 3)

As discussed earlier [1], it might be better to disable writecombine
on the CPU detection side because the root cause is unknown now.

Actually, this patch is a temporary solution to just make it work well,
it is not a proper and final solution, I hope someone will have a better
solution to fix this issue in the future.

[1] https://lore.kernel.org/patchwork/patch/1285542/

Signed-off-by: Tiezhu Yang 
Signed-off-by: Thomas Bogendoerfer

MIPS: kernel: Reserve exception base early to prevent corruption

2021-03-09T10:22:59+00:00

BMIPS is one of the few platforms that do change the exception base.
After commit 2dcb39645441 ("memblock: do not start bottom-up allocations
with kernel_end") we started seeing BMIPS boards fail to boot with the
built-in FDT being corrupted.

Before the cited commit, early allocations would be in the [kernel_end,
RAM_END] range, but after commit they would be within [RAM_START +
PAGE_SIZE, RAM_END].

The custom exception base handler that is installed by
bmips_ebase_setup() done for BMIPS5000 CPUs ends-up trampling on the
memory region allocated by unflatten_and_copy_device_tree() thus
corrupting the FDT used by the kernel.

To fix this, we need to perform an early reservation of the custom
exception space. Additional we reserve the first 4k (1k for R3k) for
either normal exception vector space (legacy CPUs) or special vectors
like cache exceptions.

Huge thanks to Serge for analysing and proposing a solution to this
issue.

Fixes: 2dcb39645441 ("memblock: do not start bottom-up allocations with kernel_end")
Reported-by: Kamal Dasu 
Debugged-by: Serge Semin 
Acked-by: Mike Rapoport 
Tested-by: Florian Fainelli 
Reviewed-by: Serge Semin 
Signed-off-by: Thomas Bogendoerfer

Revert "MIPS: Remove unused R4300 CPU support"

2021-01-22T10:39:45+00:00

This reverts commit f9065b54d437c4660e3d974ad9ce5188c068cd76.

We're adding Nintendo 64 support, so the VR4300 is no longer unused.

Signed-off-by: Lauri Kasanen 
Signed-off-by: Thomas Bogendoerfer

MIPS: Ingenic: Disable HPTLB for D0 XBurst CPUs too

2021-01-18T14:24:02+00:00

The JZ4760 has the HPTLB as well, but has a XBurst CPU with a D0 CPUID.

Disable the HPTLB for all XBurst CPUs with a D0 CPUID. In the case where
there is no HPTLB (e.g. for older SoCs), this won't have any side
effect.

Fixes: b02efeb05699 ("MIPS: Ingenic: Disable abandoned HPTLB function.")
Cc:  # 5.4
Signed-off-by: Paul Cercueil 
Reviewed-by: 周琰杰 (Zhou Yanjie) 
Signed-off-by: Thomas Bogendoerfer

MIPS: cpu-probe: remove MIPS_CPU_BP_GHIST option bit

2020-10-12T10:05:40+00:00

MIPS_CPU_BP_GHIST is only set two times and more or less immediately
used in cpu-probe.c itself. Remove this option to make room in options
word.

Signed-off-by: Thomas Bogendoerfer