linux-kernel - Re: [PATCH V3] irqchip/gic-v3: Workaround Marvell erratum 38545 when reading IAR

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Date:   Wed, 09 Mar 2022 17:50:37 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Qian Cai <quic_qiancai@...cinc.com>, will@...nel.org
Cc:     Linu Cherian <lcherian@...vell.com>, tglx@...utronix.de,
        catalin.marinas@....com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linuc.decode@...il.com
Subject: Re: [PATCH V3] irqchip/gic-v3: Workaround Marvell erratum 38545 when
 reading IAR

On 2022-03-09 17:40, Qian Cai wrote:
> On Mon, Mar 07, 2022 at 08:00:14PM +0530, Linu Cherian wrote:
>> When a IAR register read races with a GIC interrupt RELEASE event,
>> GIC-CPU interface could wrongly return a valid INTID to the CPU
>> for an interrupt that is already released(non activated) instead of 
>> 0x3ff.
>> 
>> As a side effect, an interrupt handler could run twice, once with
>> interrupt priority and then with idle priority.
>> 
>> As a workaround, gic_read_iar is updated so that it will return a
>> valid interrupt ID only if there is a change in the active priority 
>> list
>> after the IAR read on all the affected Silicons.
>> 
>> Since there are silicon variants where both 23154 and 38545 are 
>> applicable,
>> workaround for erratum 23154 has been extended to address both of 
>> them.
>> 
>> Signed-off-by: Linu Cherian <lcherian@...vell.com>
> 
> Reverting this commit from today's linux-next fixed 
> global-out-of-bounds
> accesses running CPU hotplug workloads on a non-ThunderX server.
> 
>  psci: CPU88 killed (polled 0 ms)
>  ==================================================================
>  BUG: KASAN: global-out-of-bounds in is_affected_midr_range_list
>  Read of size 4 at addr ffffa0ec80ddcc6c by task swapper/88/0
> 
>  CPU: 88 PID: 0 Comm: swapper/88 Not tainted 
> 5.17.0-rc7-next-20220309-dirty #25
>  Call trace:
>   dump_backtrace
>   show_stack
>   dump_stack_lvl
>   print_address_description.constprop.0
>   print_report
>   kasan_report
>   __asan_report_load4_noabort
>   is_affected_midr_range_list
>   is_midr_in_range_list at ./arch/arm64/include/asm/cputype.h:221
>   (inlined by) is_affected_midr_range_list at 
> arch/arm64/kernel/cpu_errata.c:41
>   verify_local_cpu_caps
>   verify_local_cpu_caps at arch/arm64/kernel/cpufeature.c:2787
>   check_local_cpu_capabilities
>   verify_local_elf_hwcaps at arch/arm64/kernel/cpufeature.c:2852
>   (inlined by) verify_local_cpu_capabilities at
> arch/arm64/kernel/cpufeature.c:2922
>   (inlined by) check_local_cpu_capabilities at
> arch/arm64/kernel/cpufeature.c:2948
>   secondary_start_kernel
>   __secondary_switched
> 
>  The buggy address belongs to the variable:
>   cavium_erratum_23154_cpus
> 
>  The buggy address belongs to the virtual mapping at
>   [ffffa0ec80dd0000, ffffa0ec82140000) created by:
>   map_kernel

Urgh... Thanks for reporting this.

Will, can you either drop this patch, or squash the following
diff in?

Thanks,

         M.

diff --git a/arch/arm64/kernel/cpu_errata.c 
b/arch/arm64/kernel/cpu_errata.c
index 1d9d4f910de7..400a1c9cac90 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -225,6 +225,7 @@ const struct midr_range cavium_erratum_23154_cpus[] 
= {
  	MIDR_ALL_VERSIONS(MIDR_OCTX2_95XXN),
  	MIDR_ALL_VERSIONS(MIDR_OCTX2_95XXMM),
  	MIDR_ALL_VERSIONS(MIDR_OCTX2_95XXO),
+	{},
  };
  #endif


-- 
Jazz is not dead. It just smells funny...