Re: [PATCH v3 03/32] irqchip/gic-v3: Workaround Cavium TX1 erratum when reading GICD_TYPER2

Robert Richter
2020-03-09T22:12:14Z

On 24.12.19 11:10:26, Marc Zyngier wrote:
> Despite the architecture spec being extremely clear about the fact
> 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 flagging all the A1 revisions
> of the distributor, but it remains unknown whether this could affect
> other revisions of this SoC (or even other SoCs from the same silicon
> vendor).
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> drivers/irqchip/irq-gic-v3.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 286f98222878..640d4db65b78 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -34,6 +34,7 @@
> #define GICD_INT_NMI_PRI (GICD_INT_DEF_PRI & ~0x80)
>
> #define FLAGS_WORKAROUND_GICR_WAKER_MSM8996 (1ULL << 0)
> +#define FLAGS_WORKAROUND_GICD_TYPER2_TX1 (1ULL << 1)
>
> struct redist_region {
> void __iomem *redist_base;
> @@ -1464,6 +1465,15 @@ static bool gic_enable_quirk_msm8996(void *data)
> return true;
> }
>
> +static bool gic_enable_quirk_tx1(void *data)
> +{
> + struct gic_chip_data *d = data;
> +
> + d->flags |= FLAGS_WORKAROUND_GICD_TYPER2_TX1;
> +
> + return true;
> +}
> +
> static bool gic_enable_quirk_hip06_07(void *data)
> {
> struct gic_chip_data *d = data;
> @@ -1502,6 +1512,12 @@ static const struct gic_quirk gic_quirks[] = {
> .mask = 0xffffffff,
> .init = gic_enable_quirk_hip06_07,
> },
> + {
> + .desc = "GICv3: Cavium TX1 GICD_TYPER2 erratum",

There is no errata number yet.

> + .iidr = 0xa100034c,
> + .mask = 0xfff00fff,
> + .init = gic_enable_quirk_tx1,

All TX1 and OcteonTX parts are affected, which is a0-a7 and b0-b7. So
the iidr/mask should be:

.iidr = 0xa000034c,
.mask = 0xe8f00fff,

> + },
> {
> }
> };
> @@ -1577,7 +1593,12 @@ static int __init gic_init_bases(void __iomem *dist_base,
> pr_info("%d SPIs implemented\n", GIC_LINE_NR - 32);
> pr_info("%d Extended SPIs implemented\n", GIC_ESPI_NR);
>
> - gic_data.rdists.gicd_typer2 = readl_relaxed(gic_data.dist_base + GICD_TYPER2);
> + /*
> + * ThunderX1 explodes on reading GICD_TYPER2, in total violation
> + * of the spec (which says that reserved addresses are RES0).
> + */
> + if (!(gic_data.flags & FLAGS_WORKAROUND_GICD_TYPER2_TX1))
> + gic_data.rdists.gicd_typer2 = readl_relaxed(gic_data.dist_base + GICD_TYPER2);

You already said that checking for ArchRev of GICD_PIDR2 isn't an
option here. Though, it could...

Thanks,

-Robert

>
> gic_data.domain = irq_domain_create_tree(handle, &gic_irq_domain_ops,
> &gic_data);
> --
> 2.20.1
>