linux-kernel - Re: [PATCH] irqchip/gic-v3: Workaround Cavium erratum 38539 when reading GICD

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Message-ID: <20200312183257.xylz6seamaw3svl4@rric.localdomain>
Date:   Thu, 12 Mar 2020 19:32:57 +0100
From:   Robert Richter <rrichter@...vell.com>
To:     Marc Zyngier <maz@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Mark Salter <msalter@...hat.com>
Subject: Re: [PATCH] irqchip/gic-v3: Workaround Cavium erratum 38539 when
 reading GICD_TYPER2

On 11.03.20 11:56:49, Marc Zyngier wrote:
> Despite the architecture spec requiring that reserved registers in the GIC
> distributor memory map are RES0 (and thus are not allowed to generate
> an exception), the Cavium ThunderX (aka TX1) SoC explodes as such:
> 
> [    0.000000] GICv3: GIC: Using split EOI/Deactivate mode
> [    0.000000] GICv3: 128 SPIs implemented
> [    0.000000] GICv3: 0 Extended SPIs implemented
> [    0.000000] Internal error: synchronous external abort: 96000210 [#1] SMP
> [    0.000000] Modules linked in:
> [    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc4-00035-g3cf6a3d5725f #7956
> [    0.000000] Hardware name: cavium,thunder-88xx (DT)
> [    0.000000] pstate: 60000085 (nZCv daIf -PAN -UAO)
> [    0.000000] pc : __raw_readl+0x0/0x8
> [    0.000000] lr : gic_init_bases+0x110/0x560
> [    0.000000] sp : ffff800011243d90
> [    0.000000] x29: ffff800011243d90 x28: 0000000000000000
> [    0.000000] x27: 0000000000000018 x26: 0000000000000002
> [    0.000000] x25: ffff8000116f0000 x24: ffff000fbe6a2c80
> [    0.000000] x23: 0000000000000000 x22: ffff010fdc322b68
> [    0.000000] x21: ffff800010a7a208 x20: 00000000009b0404
> [    0.000000] x19: ffff80001124dad0 x18: 0000000000000010
> [    0.000000] x17: 000000004d8d492b x16: 00000000f67eb9af
> [    0.000000] x15: ffffffffffffffff x14: ffff800011249908
> [    0.000000] x13: ffff800091243ae7 x12: ffff800011243af4
> [    0.000000] x11: ffff80001126e000 x10: ffff800011243a70
> [    0.000000] x9 : 00000000ffffffd0 x8 : ffff80001069c828
> [    0.000000] x7 : 0000000000000059 x6 : ffff8000113fb4d1
> [    0.000000] x5 : 0000000000000001 x4 : 0000000000000000
> [    0.000000] x3 : 0000000000000000 x2 : 0000000000000000
> [    0.000000] x1 : 0000000000000000 x0 : ffff8000116f000c
> [    0.000000] Call trace:
> [    0.000000]  __raw_readl+0x0/0x8
> [    0.000000]  gic_of_init+0x188/0x224
> [    0.000000]  of_irq_init+0x200/0x3cc
> [    0.000000]  irqchip_init+0x1c/0x40
> [    0.000000]  init_IRQ+0x160/0x1d0
> [    0.000000]  start_kernel+0x2ec/0x4b8
> [    0.000000] Code: a8c47bfd d65f03c0 d538d080 d65f03c0 (b9400000)
> 
> when reading the GICv4.1 GICD_TYPER2 register, which is unexpected...
> 
> Work around it by adding a new quirk for the following variants:
> 
>  ThunderX: CN88xx
>  OCTEON TX: CN83xx, CN81xx
>  OCTEON TX2: CN93xx, CN96xx, CN98xx, CNF95xx*
> 
> and use this flag to avoid accessing GICD_TYPER2. Note that all
> reserved registers (including redistributors and ITS) are impacted
> by this erratum, but that only GICD_TYPER2 has to be worked around
> so far.
> 
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> Cc: Mark Salter <msalter@...hat.com>
> Cc: Robert Richter <rrichter@...vell.com>

Tested on a Cavium Thunder cn88xx.

Acked-by: Robert Richter <rrichter@...vell.com>
Tested-by: Robert Richter <rrichter@...vell.com>

Thanks,

-Robert