Re: [PATCH] irqchip/gicv3-its: Add workaround for QDF2400 ITS erratum 0065

[Marc Zyngier]

On Sun, Mar 05 2017 at  3:23:56 pm GMT, Shanker Donthineni <shankerd@xxxxxxxxxxxxxx> wrote:
> On Qualcomm Datacenter Technologies QDF2400 SoCs, the ITS hardware
> implementation uses 16Bytes for Interrupt Translation Entry (ITTE),

nit: Interrupt Translation Entry is abbreviated as ITE. I know the vITS
has the ITTE thing all over the place, which I plan to address. No need
to respin for that.

> but reports an incorrect value of 8Bytes in GITS_TYPER.ITTE_size.
>
> It might cause kernel memory corruption depending on the number
> of MSI(x) that are configured and the amount of memory that has
> been allocated for ITTEs in its_create_device().
>
> This patch fixes the potential memory corruption by setting the
> correct ITTE size to 16Bytes.
>
> Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
> ---
>  Documentation/arm64/silicon-errata.txt |  1 +
>  arch/arm64/Kconfig                     | 10 ++++++++++
>  drivers/irqchip/irq-gic-v3-its.c       | 16 ++++++++++++++++
>  3 files changed, 27 insertions(+)
>
> diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
> index a71b809..2f66683 100644
> --- a/Documentation/arm64/silicon-errata.txt
> +++ b/Documentation/arm64/silicon-errata.txt
> @@ -68,3 +68,4 @@ stable kernels.
>  |                |                 |                 |                             |
>  | Qualcomm Tech. | Falkor v1       | E1003           | QCOM_FALKOR_ERRATUM_1003    |
>  | Qualcomm Tech. | Falkor v1       | E1009           | QCOM_FALKOR_ERRATUM_1009    |
> +| Qualcomm Tech. | QDF2400 ITS     | E0065           | QCOM_QDF2400_ERRATUM_0065   |
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 896eba6..6bd51fb 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -509,6 +509,16 @@ config QCOM_FALKOR_ERRATUM_1009
>  
>  	  If unsure, say Y.
>  
> +config QCOM_QDF2400_ERRATUM_0065
> +	bool "QDF2400 E0065: Incorrect GITS_TYPER.ITT_Entry_size"
> +	default y
> +	help
> +	  On Qualcomm Datacenter Technologies QDF2400 SoC, ITS hardware reports
> +	  ITTE size incorrectly. The GITS_TYPER.ITT_Entry_size field should have
> +	  been indicated as 16Bytes (0xf), not 8Bytes (0x7).
> +
> +	  If unsure, say Y.
> +
>  endmenu
>  
>  
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 2320100..86bd428 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -1601,6 +1601,14 @@ static void __maybe_unused its_enable_quirk_cavium_23144(void *data)
>  	its->flags |= ITS_FLAGS_WORKAROUND_CAVIUM_23144;
>  }
>  
> +static void __maybe_unused its_enable_quirk_qdf2400_e0065(void *data)
> +{
> +	struct its_node *its = data;
> +
> +	/* On QDF2400, the size of the ITTE is 16Bytes */
> +	its->ite_size = 16;
> +}
> +
>  static const struct gic_quirk its_quirks[] = {
>  #ifdef CONFIG_CAVIUM_ERRATUM_22375
>  	{
> @@ -1618,6 +1626,14 @@ static void __maybe_unused its_enable_quirk_cavium_23144(void *data)
>  		.init	= its_enable_quirk_cavium_23144,
>  	},
>  #endif
> +#ifdef CONFIG_QCOM_QDF2400_ERRATUM_0065
> +	{
> +		.desc	= "ITS: QDF2400 erratum 0065",
> +		.iidr	= 0x00001070, /* QDF2400 ITS rev 1.x */
> +		.mask	= 0xffffffff,
> +		.init	= its_enable_quirk_qdf2400_e0065,
> +	},
> +#endif
>  	{
>  	}
>  };

OK, that's pretty bad. Should this be CC stable?

Thanks,

	M.
-- 
Jazz is not dead, it just smell funny.