Re: [RESEND,PATCH 03/13] iommu/mediatek: Add mtk_iommu_pgtable structure

chao hao
2020-02-25T07:27:08Z

On Sat, 2020-02-15 at 20:17 +0800, Yong Wu wrote:
> On Tue, 2019-12-31 at 17:39 +0800, chao hao wrote:
> > On Mon, 2019-12-16 at 20:13 +0800, Yong Wu wrote:
> > > On Mon, 2019-11-04 at 19:52 +0800, Chao Hao wrote:
> > > > Start with this patch, we will change the SW architecture
> > > > to support multiple domains. SW architecture will has a big change,
> > > > so we need to modify a little bit by more than one patch.
> > > > The new SW overall architecture is as below:
> > > >
> > > > iommu0 iommu1
> > > > | |
> > > > -----------
> > > > |
> > > > mtk_iommu_pgtable
> > > > |
> > > > ------------------------------------------
> > > > | | |
> > > > mtk_iommu_domain1 mtk_iommu_domain2 mtk_iommu_domain3
> > > > | | |
> > > > iommu_group1 iommu_group2 iommu_group3
> > > > | | |
> > > > iommu_domain1 iommu_domain2 iommu_domain3
> > > > | | |
> > > > iova region1(normal) iova region2(CCU) iova region3(VPU)
> > > >
> > > > For current structure, no matter how many iommus there are,
> > > > they use the same page table to simplify the usage of module.
> > > > In order to make the software architecture more explicit, this
> > > > patch will create a global mtk_iommu_pgtable structure to describe
> > > > page table and all the iommus use it.
> > >
> > > Thanks for the hard work of this file. Actually this patch and the later
> > > ones confuse me. Why do you make this flow change?
> > > for making the code "more explicit" or for adding multi-domain support
> > > in 13/13.
> > >
> > > IMHO, the change is unnecessary.
> > > a) For me, this change has no improvement. currently we use a global
> > > mtk_iommu_get_m4u_data to get the M4U data. I will be very glad if you
> > > could get rid of it. But in this patchset, You use a another global
> > > mtk_iommu_pgtable to instead. For me. It has no improvement.
> >
> > Thanks for you advice!
> >
> > For current SW arch, all the IOMMU HW use the same page table, we can
> > use a global mtk_iommu_pgtable to discribe the information of page table
>
> What's your plan if the 4GB iova range is not enough for us in future?
> Do you plan to add a new global mtk_iommu_pgtable again?
>
if the 4GB iova range is not enough, we only need to modify
mtk_domain_data structure: min_iova and max_iova, Compare with current
SW arch:
dom->domain.geometry.aperture_start = 0;
dom->domain.geometry.aperture_end = DMA_BIT_MASK(32);
==>
dom->domain.geometry.aperture_start = pgtable->dom_region->min_iova;
dom->domain.geometry.aperture_end = pgtable->dom_region->max_iova;

struct mtk_domain_data {
dma_addr_t min_iova;
dma_addr_t max_iova;
};

> > and all the IOMMU attach it, I think that it is more clear and
> > unambiguous. For beginners, it maybe more easily explicable?
>
> I still don't get the necessity of this change. it is only for making
> code clear from your point for view, right?
>
> This code has been reviewed for many years, I don't know why you think
> it is ambiguous. it is clear for me at lease. and I will complain that
> you add a new global variable in this change.
>
> > >
> > > b) This patchset break the original flow. device_group give you a
> > > software chance for initializing, then you move pagetable allocating
> > > code into it. But it isn't device_group job.
> > >
> >
> > As is shown above diagram, mtk_iommu_pgtable includes iommu_group and
> > iommu_domain,so we need to allocate mtk_iommu_pgtable and initialize it
> > in device_group firstly,and then execute the original flow, it only
> > changes place for creating mtk_iommu_pgtable and don't break original
> > device_group flow.
>
> I understand you have to do this change after you adjust the structure.
> I mean that it may be not proper since allocating pagetable should not
> be done in device_group logically. From here, Could we get this change
> looks not good?.
>
gentle ping ...

> > > I can not decide if your flow is right. But if you only want to add
> > > support multi-domain, I guess you could extend the current "m4u_group"
> > > to a array "m4u_group[N]". It may be more simple. To make mt6779
> > > progress easily, I suggest you can use this way to support multi-domain
> > > firstly. Then you could send this new mtk_iommu_pgtable patchset for the
> > > code "more explicit" if you insist.
>
> Could you help try this way if it could meet your requirement? Then
> let's compare which one is better.
>
>
> BTW, your patches(including v2) cause hangup as below since
> "data->m4u_dom" was uninitialized.
>
>
> Unable to handle kernel NULL pointer dereference at virtual address
> 0000000000000010
> ...
> pc : mtk_iommu_tlb_flush_page_nosync+0x38/0xb8
> lr : __arm_v7s_unmap+0x174/0x598
> ...
> Call trace:
> mtk_iommu_tlb_flush_page_nosync+0x38/0xb8
> __arm_v7s_unmap+0x174/0x598
> arm_v7s_unmap+0x30/0x48
> mtk_iommu_unmap+0x20/0x28
> __iommu_unmap+0xa4/0xf8
> iommu_unmap+0x44/0x90
>
yes, you are right. I will modify it in next version, thanks

> > >
> > > > The diagram is as below:
> > > >
> > > > mtk_iommu_data1(MM) mtk_iommu_data2(APU)
> > > > | |
> > > > | |
> > > > ------mtk_iommu_pgtable-----
> > > >
> > > > We need to create global mtk_iommu_pgtable to include all the iova
> > > > regions firstly and special iova regions by divided based on it,
> > > > so the information of pgtable needs to be created in device_group.
> > > >
> > > > Signed-off-by: Chao Hao <chao.hao@mediatek.com>
> > > > ---
> > > > drivers/iommu/mtk_iommu.c | 84 +++++++++++++++++++++++++++++++++++++++
> > > > drivers/iommu/mtk_iommu.h | 1 +
> > > > 2 files changed, 85 insertions(+)
> > > >
> > > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > > > index f2847e661137..fcbde6b0f58d 100644
> > > > --- a/drivers/iommu/mtk_iommu.c
> > > > +++ b/drivers/iommu/mtk_iommu.c
> > > > @@ -123,6 +123,12 @@ struct mtk_iommu_domain {
> > > > struct iommu_domain domain;
> > > > };
> > > >
> > > > +struct mtk_iommu_pgtable {
> > > > + struct io_pgtable_cfg cfg;
> > > > + struct io_pgtable_ops *iop;
> > > > +};
> > > > +
> > > > +static struct mtk_iommu_pgtable *share_pgtable;
> > > > static const struct iommu_ops mtk_iommu_ops;
> > > >
> > > > /*
> > > > @@ -170,6 +176,11 @@ static struct mtk_iommu_data *mtk_iommu_get_m4u_data(void)
> > > > return NULL;
> > > > }
> > > >
> > > > +static struct mtk_iommu_pgtable *mtk_iommu_get_pgtable(void)
> > > > +{
> > > > + return share_pgtable;
> > > > +}
> > > > +
> > > > static struct mtk_iommu_domain *to_mtk_domain(struct iommu_domain *dom)
> > > > {
> > > > return container_of(dom, struct mtk_iommu_domain, domain);
> > > > @@ -322,6 +333,13 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom)
> > > > {
> > > > struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
> > > >
> > > > + if (data->pgtable) {
> > > > + dom->cfg = data->pgtable->cfg;
> > > > + dom->iop = data->pgtable->iop;
> > > > + dom->domain.pgsize_bitmap = data->pgtable->cfg.pgsize_bitmap;
> > > > + return 0;
> > > > + }
> > > > +
> > > > dom->cfg = (struct io_pgtable_cfg) {
> > > > .quirks = IO_PGTABLE_QUIRK_ARM_NS |
> > > > IO_PGTABLE_QUIRK_NO_PERMS |
> > > > @@ -345,6 +363,61 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom)
> > > > return 0;
> > > > }
> > > >
> > > > +static struct mtk_iommu_pgtable *create_pgtable(struct mtk_iommu_data *data)
> > > > +{
> > > > + struct mtk_iommu_pgtable *pgtable;
> > > > +
> > > > + pgtable = kzalloc(sizeof(*pgtable), GFP_KERNEL);
> > > > + if (!pgtable)
> > > > + return ERR_PTR(-ENOMEM);
> > > > +
> > > > + pgtable->cfg = (struct io_pgtable_cfg) {
> > > > + .quirks = IO_PGTABLE_QUIRK_ARM_NS |
> > > > + IO_PGTABLE_QUIRK_NO_PERMS |
> > > > + IO_PGTABLE_QUIRK_TLBI_ON_MAP |
> > > > + IO_PGTABLE_QUIRK_ARM_MTK_EXT,
> > > > + .pgsize_bitmap = mtk_iommu_ops.pgsize_bitmap,
> > > > + .ias = 32,
> > > > + .oas = 34,
> > > > + .tlb = &mtk_iommu_flush_ops,
> > > > + .iommu_dev = data->dev,
> > > > + };
> > > > +
> > > > + pgtable->iop = alloc_io_pgtable_ops(ARM_V7S, &pgtable->cfg, data);
> > > > + if (!pgtable->iop) {
> > > > + dev_err(data->dev, "Failed to alloc io pgtable\n");
> > > > + return ERR_PTR(-EINVAL);
> > > > + }
> > > > +
> > > > + dev_info(data->dev, "%s create pgtable done\n", __func__);
> > > > +
> > > > + return pgtable;
> > > > +}
> > > > +
> > > > +static int mtk_iommu_attach_pgtable(struct mtk_iommu_data *data,
> > > > + struct device *dev)
> > > > +{
> > > > + struct mtk_iommu_pgtable *pgtable = mtk_iommu_get_pgtable();
> > > > +
> > > > + /* create share pgtable */
> > > > + if (!pgtable) {
> > > > + pgtable = create_pgtable(data);
> > > > + if (IS_ERR(pgtable)) {
> > > > + dev_err(data->dev, "Failed to create pgtable\n");
> > > > + return -ENOMEM;
> > > > + }
> > > > +
> > > > + share_pgtable = pgtable;
> > > > + }
> > > > +
> > > > + /* binding to pgtable */
> > > > + data->pgtable = pgtable;
> > > > +
> > > > + dev_info(data->dev, "m4u%d attach_pgtable done!\n", data->m4u_id);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > static struct iommu_domain *mtk_iommu_domain_alloc(unsigned type)
> > > > {
> > > > struct mtk_iommu_domain *dom;
> > > > @@ -508,10 +581,21 @@ static void mtk_iommu_remove_device(struct device *dev)
> > > > static struct iommu_group *mtk_iommu_device_group(struct device *dev)
> > > > {
> > > > struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
> > > > + struct mtk_iommu_pgtable *pgtable;
> > > > + int ret = 0;
> > > >
> > > > if (!data)
> > > > return ERR_PTR(-ENODEV);
> > > >
> > > > + pgtable = data->pgtable;
> > > > + if (!pgtable) {
> > > > + ret = mtk_iommu_attach_pgtable(data, dev);
> > > > + if (ret) {
> > > > + dev_err(data->dev, "Failed to device_group\n");
> > > > + return NULL;
> > > > + }
> > > > + }
> > > > +
> > > > /* All the client devices are in the same m4u iommu-group */
> > > > if (!data->m4u_group) {
> > > > data->m4u_group = iommu_group_alloc();
> > > > diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> > > > index 132dc765a40b..dd5f19f78b62 100644
> > > > --- a/drivers/iommu/mtk_iommu.h
> > > > +++ b/drivers/iommu/mtk_iommu.h
> > > > @@ -61,6 +61,7 @@ struct mtk_iommu_data {
> > > > struct clk *bclk;
> > > > phys_addr_t protect_base; /* protect memory base */
> > > > struct mtk_iommu_suspend_reg reg;
> > > > + struct mtk_iommu_pgtable *pgtable;
> > > > struct mtk_iommu_domain *m4u_dom;
> > > > struct iommu_group *m4u_group;
> > > > bool enable_4GB;
> > >
> > >
> >
> >
>
>