IOMMU Archive on lore.kernel.org
 help / color / Atom feed
From: Robin Murphy <robin.murphy@arm.com>
To: kholk11@gmail.com, linux-arm-msm@vger.kernel.org
Cc: marijns95@gmail.com, agross@kernel.org, iommu@lists.linux-foundation.org
Subject: Re: [PATCH v4 2/7] iommu/qcom: Use the asid read from device-tree if specified
Date: Tue, 15 Oct 2019 13:09:57 +0100
Message-ID: <25f3e314-3fcc-fc4f-e7b5-4f28418ea02f@arm.com> (raw)
In-Reply-To: <20191001220205.6423-3-kholk11@gmail.com>

On 01/10/2019 23:02, kholk11@gmail.com wrote:
> From: AngeloGioacchino Del Regno <kholk11@gmail.com>
> 
> As specified in this driver, the context banks are 0x1000 apart.
> Problem is that sometimes the context number (our asid) does not
> match this logic and we end up using the wrong one: this starts
> being a problem in the case that we need to send TZ commands
> to do anything on a specific context.
> 
> For this reason, read the ASID from the DT if the property
> "qcom,ctx-num" is present on the IOMMU context node.

Can you clarify exactly what the situation is here? Is the hypervisor 
broken in that it presents context banks at made-up offsets and fails to 
correctly associate those offsets with the real underlying hardware 
context in some cases? Or is the hypervisor actually intercepting 
TTBR/CONTEXTIDR/TLBI* writes such that we don't actually have control 
over the ASID used by a given context bank (which I would also consider 
broken)? Or is "context number" a specific thing in the SCM interface 
which represents neither of the above?

At the moment, it seems like a bit too much is being conflated here just 
because of some implicit behaviour in the driver.

Robin.

> Signed-off-by: AngeloGioacchino Del Regno <kholk11@gmail.com>
> ---
>   .../devicetree/bindings/iommu/qcom,iommu.txt    |  1 +
>   drivers/iommu/qcom_iommu.c                      | 17 ++++++++++++++---
>   2 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iommu/qcom,iommu.txt b/Documentation/devicetree/bindings/iommu/qcom,iommu.txt
> index 059139abce35..ba0b77889f02 100644
> --- a/Documentation/devicetree/bindings/iommu/qcom,iommu.txt
> +++ b/Documentation/devicetree/bindings/iommu/qcom,iommu.txt
> @@ -46,6 +46,7 @@ to non-secure vs secure interrupt line.
>                        for routing of context bank irq's to secure vs non-
>                        secure lines.  (Ie. if the iommu contains secure
>                        context banks)
> +- qcom,ctx-num     : The number associated to the context bank
>   
>   
>   ** Examples:
> diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c
> index c31e7bc4ccbe..504ca69adc5a 100644
> --- a/drivers/iommu/qcom_iommu.c
> +++ b/drivers/iommu/qcom_iommu.c
> @@ -585,7 +585,8 @@ static int qcom_iommu_of_xlate(struct device *dev, struct of_phandle_args *args)
>   	 * index into qcom_iommu->ctxs:
>   	 */
>   	if (WARN_ON(asid < 1) ||
> -	    WARN_ON(asid > qcom_iommu->num_ctxs))
> +	    WARN_ON(asid > qcom_iommu->num_ctxs) ||
> +	    WARN_ON(qcom_iommu->ctxs[asid - 1] == NULL))
>   		return -EINVAL;
>   
>   	if (!fwspec->iommu_priv) {
> @@ -693,7 +694,8 @@ static int qcom_iommu_sec_ptbl_init(struct device *dev)
>   
>   static int get_asid(const struct device_node *np)
>   {
> -	u32 reg;
> +	u32 reg, val;
> +	int asid;
>   
>   	/* read the "reg" property directly to get the relative address
>   	 * of the context bank, and calculate the asid from that:
> @@ -701,7 +703,16 @@ static int get_asid(const struct device_node *np)
>   	if (of_property_read_u32_index(np, "reg", 0, &reg))
>   		return -ENODEV;
>   
> -	return reg / 0x1000;      /* context banks are 0x1000 apart */
> +	/* Context banks are 0x1000 apart but, in some cases, the ASID
> +	 * number doesn't match to this logic and needs to be passed
> +	 * from the DT configuration explicitly.
> +	 */
> +	if (of_property_read_u32(np, "qcom,ctx-num", &val))
> +		asid = reg / 0x1000;
> +	else
> +		asid = val;
> +
> +	return asid;
>   }
>   
>   static int qcom_iommu_ctx_probe(struct platform_device *pdev)
> 
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-01 22:01 [PATCH v4 0/7] Add support for QCOM IOMMU v2 and 500 kholk11
2019-10-01 22:01 ` [PATCH v4 1/7] firmware: qcom: scm: Add function to set IOMMU pagetable addressing kholk11
2019-10-15 11:14   ` Joerg Roedel
2019-10-15 12:33     ` AngeloGioacchino Del Regno
2019-10-15 12:40       ` Joerg Roedel
2019-10-15 13:09         ` AngeloGioacchino Del Regno
2019-10-01 22:02 ` [PATCH v4 2/7] iommu/qcom: Use the asid read from device-tree if specified kholk11
2019-10-15 12:09   ` Robin Murphy [this message]
2019-10-15 13:06     ` AngeloGioacchino Del Regno
2019-10-01 22:02 ` [PATCH v4 3/7] iommu/qcom: Write TCR before TTBRs to fix ASID access behavior kholk11
2019-10-01 22:02 ` [PATCH v4 4/7] iommu/qcom: Properly reset the IOMMU context kholk11
2019-10-02 11:29   ` Robin Murphy
2019-10-01 22:02 ` [PATCH v4 5/7] iommu/qcom: Add support for AArch64 IOMMU pagetables kholk11
2019-10-01 22:02 ` [PATCH v4 6/7] iommu/qcom: Index contexts by asid number to allow asid 0 kholk11
2019-10-01 22:02 ` [PATCH v4 7/7] iommu/qcom: Add support for QCIOMMUv2 and QCIOMMU-500 secured contexts kholk11
2019-10-05  4:56 ` [PATCH v4 0/7] Add support for QCOM IOMMU v2 and 500 Bjorn Andersson
2019-10-05  9:32   ` AngeloGioacchino Del Regno

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=25f3e314-3fcc-fc4f-e7b5-4f28418ea02f@arm.com \
    --to=robin.murphy@arm.com \
    --cc=agross@kernel.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=kholk11@gmail.com \
    --cc=linux-arm-msm@vger.kernel.org \
    --cc=marijns95@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

IOMMU Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-iommu/0 linux-iommu/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-iommu linux-iommu/ https://lore.kernel.org/linux-iommu \
		iommu@lists.linux-foundation.org
	public-inbox-index linux-iommu

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.linux-foundation.lists.iommu


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git