Subject: [PATCH v2] iommu/io-pgtable: Rationalise quirk handling

From: [email-masked] (Laurent Pinchart)
Date: Fri, 12 Feb 2016 19:24:06 +0200

Hi Robin,

Thank you for the patch.

On Friday 12 February 2016 17:09:46 Robin Murphy wrote:
> As the number of io-pgtable implementations grows beyond 1, it's time
> to rationalise the quirks mechanism before things have a chance to
> start getting really ugly and out-of-hand.
> 
> To that end:
> - Indicate exactly which quirks each format can/does support.
> - Fail creating a table if a caller wants unsupported quirks.
> - Properly document where each quirk applies and why.
> 
> Signed-off-by: Robin Murphy <[email-masked]>
> ---
> 
> Just to allay any confusion, I intend this as a followup to the
> short-descriptor[1] and Mediatek IOMMU[2] patches, rather than a
> crucial addition, so it can either get picked up along with those
> or wait 'til later.
> 
> v2:
> - Use unsigned long for the bitmap.
> - Do format-specific checks inline.
> - Enough of a difference that I don't feel comfortable putting
>   Laurent's reviewed-by from v1 on it...

Here it is again.

Reviewed-by: Laurent Pinchart <[email-masked]>

> [1]:http://thread.gmane.org/gmane.linux.kernel.iommu/12007
> [2]:http://thread.gmane.org/gmane.linux.kernel.iommu/11974
> 
>  drivers/iommu/io-pgtable-arm-v7s.c |  5 +++++
>  drivers/iommu/io-pgtable-arm.c     | 13 +++++++++++--
>  drivers/iommu/io-pgtable.h         | 22 ++++++++++++++++++----
>  3 files changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/io-pgtable-arm-v7s.c
> b/drivers/iommu/io-pgtable-arm-v7s.c index d39a021..9fcceb1 100644
> --- a/drivers/iommu/io-pgtable-arm-v7s.c
> +++ b/drivers/iommu/io-pgtable-arm-v7s.c
> @@ -623,6 +623,11 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct
> io_pgtable_cfg *cfg, if (cfg->ias > ARM_V7S_ADDR_BITS || cfg->oas >
> ARM_V7S_ADDR_BITS) return NULL;
> 
> +	if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
> +			    IO_PGTABLE_QUIRK_NO_PERMS |
> +			    IO_PGTABLE_QUIRK_TLBI_ON_MAP))
> +		return NULL;
> +
>  	data = kmalloc(sizeof(*data), GFP_KERNEL);
>  	if (!data)
>  		return NULL;
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 4095af2..debdf04 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -658,8 +658,12 @@ static struct io_pgtable *
>  arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
>  {
>  	u64 reg;
> -	struct arm_lpae_io_pgtable *data = arm_lpae_alloc_pgtable(cfg);
> +	struct arm_lpae_io_pgtable *data;
> 
> +	if (cfg->quirks & ~IO_PGTABLE_QUIRK_ARM_NS)
> +		return NULL;
> +
> +	data = arm_lpae_alloc_pgtable(cfg);
>  	if (!data)
>  		return NULL;
> 
> @@ -742,8 +746,13 @@ static struct io_pgtable *
>  arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
>  {
>  	u64 reg, sl;
> -	struct arm_lpae_io_pgtable *data = arm_lpae_alloc_pgtable(cfg);
> +	struct arm_lpae_io_pgtable *data;
> 
> +	/* The NS quirk doesn't apply at stage 2 */
> +	if (cfg->quirks)
> +		return NULL;
> +
> +	data = arm_lpae_alloc_pgtable(cfg);
>  	if (!data)
>  		return NULL;
> 
> diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
> index 4faee7d..d4f5027 100644
> --- a/drivers/iommu/io-pgtable.h
> +++ b/drivers/iommu/io-pgtable.h
> @@ -47,10 +47,24 @@ struct iommu_gather_ops {
>   *                 page table walker.
>   */
>  struct io_pgtable_cfg {
> -	#define IO_PGTABLE_QUIRK_ARM_NS		BIT(0) /* Set NS bit in PTEs */
> -	#define IO_PGTABLE_QUIRK_NO_PERMS	BIT(1) /* No AP/XN bits */
> -	#define IO_PGTABLE_QUIRK_TLBI_ON_MAP	BIT(2) /* TLB Inv. on map */
> -	int				quirks;
> +	/*
> +	 * IO_PGTABLE_QUIRK_ARM_NS: (ARM formats) Set NS and NSTABLE bits in
> +	 *	stage 1 PTEs, for hardware which insists on validating them
> +	 *	even in	non-secure state where they should normally be ignored.
> +	 *
> +	 * IO_PGTABLE_QUIRK_NO_PERMS: Ignore the IOMMU_READ, IOMMU_WRITE and
> +	 *	IOMMU_NOEXEC flags and map everything with full access, for
> +	 *	hardware which does not implement the permissions of a given
> +	 *	format, and/or requires some format-specific default value.
> +	 *
> +	 * IO_PGTABLE_QUIRK_TLBI_ON_MAP: If the format forbids caching invalid
> +	 *	(unmapped) entries but the hardware might do so anyway, perform
> +	 *	TLB maintenance when mapping as well as when unmapping.
> +	 */
> +	#define IO_PGTABLE_QUIRK_ARM_NS		BIT(0)
> +	#define IO_PGTABLE_QUIRK_NO_PERMS	BIT(1)
> +	#define IO_PGTABLE_QUIRK_TLBI_ON_MAP	BIT(2)
> +	unsigned long			quirks;
>  	unsigned long			pgsize_bitmap;
>  	unsigned int			ias;
>  	unsigned int			oas;

-- 
Regards,

Laurent Pinchart