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Message-id: <009a01ce814d$840b48c0$8c21da40$@samsung.com>
Date: Mon, 15 Jul 2013 20:21:56 +0900
From: Cho KyongHo <pullip.cho@...sung.com>
To: 'Bartlomiej Zolnierkiewicz' <b.zolnierkie@...sung.com>
Cc: 'Linux ARM Kernel' <linux-arm-kernel@...ts.infradead.org>,
'Linux IOMMU' <iommu@...ts.linux-foundation.org>,
'Linux Kernel' <linux-kernel@...r.kernel.org>,
'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>,
'Hyunwoong Kim' <khw0178.kim@...sung.com>,
'Joerg Roedel' <joro@...tes.org>,
'Kukjin Kim' <kgene.kim@...sung.com>,
'Prathyush' <prathyush.k@...sung.com>,
'Rahul Sharma' <rahul.sharma@...sung.com>,
'Subash Patel' <supash.ramaswamy@...aro.org>,
'Keyyoung Park' <keyyoung.park@...sung.com>,
'Grant Grundler' <grundler@...omium.org>
Subject: RE: [PATCH v7 3/9] iommu/exynos: fix page table maintenance
> -----Original Message-----
> From: Bartlomiej Zolnierkiewicz [mailto:b.zolnierkie@...sung.com]
> Sent: Friday, July 12, 2013 2:38 AM
>
> Hi,
>
> Some minor nitpicks below.
>
> On Friday, July 05, 2013 09:29:18 PM Cho KyongHo wrote:
> > This prevents allocating lv2 page table for the lv1 page table entry
> > that already has 1MB page mapping. In addition some BUG_ON() is
> > changed to WARN_ON().
> >
> > Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
> > ---
> > drivers/iommu/exynos-iommu.c | 34 ++++++++++++++++++++++++++--------
> > 1 files changed, 26 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> > index e3be3e5..2bfe9fa 100644
> > --- a/drivers/iommu/exynos-iommu.c
> > +++ b/drivers/iommu/exynos-iommu.c
> > @@ -862,12 +862,14 @@ static unsigned long *alloc_lv2entry(unsigned long *sent, unsigned long iova,
> > pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> > BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
> > if (!pent)
> > - return NULL;
> > + return ERR_PTR(-ENOMEM);
> >
> > *sent = mk_lv1ent_page(__pa(pent));
> > *pgcounter = NUM_LV2ENTRIES;
> > pgtable_flush(pent, pent + NUM_LV2ENTRIES);
> > pgtable_flush(sent, sent + 1);
> > + } else if (lv1ent_section(sent)) {
> > + return ERR_PTR(-EADDRINUSE);
> > }
> >
> > return page_entry(sent, iova);
> > @@ -944,16 +946,16 @@ static int exynos_iommu_map(struct iommu_domain *domain, unsigned long iova,
> > pent = alloc_lv2entry(entry, iova,
> > &priv->lv2entcnt[lv1ent_offset(iova)]);
> >
> > - if (!pent)
> > - ret = -ENOMEM;
> > + if (IS_ERR(pent))
> > + ret = PTR_ERR(pent);
> > else
> > ret = lv2set_page(pent, paddr, size,
> > &priv->lv2entcnt[lv1ent_offset(iova)]);
> > }
> >
> > if (ret) {
> > - pr_debug("%s: Failed to map iova 0x%lx/0x%x bytes\n",
> > - __func__, iova, size);
> > + pr_err("%s: Failed(%d) to map iova 0x%#x bytes @ %#lx\n",
> > + __func__, ret, size, iova);
> > }
>
> Intendation is a bit weird, it should be more like:
>
> pr_err("%s: Failed(%d) to map iova 0x%#x bytes @ %#lx\n",
> __func__, ret, size, iova);
>
> to be consistent with the rest of the driver.
>
> You could have also removed superfluous braces while at it.
>
Do you think it is better to read the code?
Hmm, I think it is better too.
Thanks.
> > spin_unlock_irqrestore(&priv->pgtablelock, flags);
> > @@ -968,6 +970,7 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
> > struct sysmmu_drvdata *data;
> > unsigned long flags;
> > unsigned long *ent;
> > + size_t err_page;
> >
> > BUG_ON(priv->pgtable == NULL);
> >
> > @@ -976,7 +979,8 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
> > ent = section_entry(priv->pgtable, iova);
> >
> > if (lv1ent_section(ent)) {
> > - BUG_ON(size < SECT_SIZE);
> > + if (WARN_ON(size < SECT_SIZE))
> > + goto err;
> >
> > *ent = 0;
> > pgtable_flush(ent, ent + 1);
> > @@ -1008,7 +1012,8 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain,
> > }
> >
> > /* lv1ent_large(ent) == true here */
> > - BUG_ON(size < LPAGE_SIZE);
> > + if (WARN_ON(size < LPAGE_SIZE))
> > + goto err;
> >
> > memset(ent, 0, sizeof(*ent) * SPAGES_PER_LPAGE);
> > pgtable_flush(ent, ent + SPAGES_PER_LPAGE);
> > @@ -1023,8 +1028,21 @@ done:
> > sysmmu_tlb_invalidate_entry(data->dev, iova);
> > spin_unlock_irqrestore(&priv->lock, flags);
> >
> > -
> > return size;
> > +err:
> > + spin_unlock_irqrestore(&priv->pgtablelock, flags);
> > +
> > + err_page = (
> > + ((unsigned long)ent - (unsigned long)priv->pgtable)
> > + < (NUM_LV1ENTRIES * sizeof(long))
>
> Maybe you could add LV1TABLE_SIZE define and use it here (there is
> already a LV2TABLE_SIZE define)?
Yes. But, LV2TABLE_SIZE is used in more places than one.
I do not feel that it is needed to define LV1TABLE_SIZE for the single line.
>
> > + ) ? SECT_SIZE : LPAGE_SIZE;
>
> It also seems that err_page should be of unsigned long type, no need
> to make it size_t one.
>
err_page is the page size.
I agree that the name of the variable is not proper to indicate size.
> The above code is quite ugly currently, it could be rewritten into
> something prettier, i.e.:
>
> err_page = (unsigned long)ent - (unsigned long)priv->pgtable;
> err_page = (err_page < LV1TABLE_SIZE) ? SECT_SIZE : LPAGE_SIZE;
>
Ah, this is the reason that you addresses err_page could be unsigned long.
I agree that it is prettier.
> > + pr_err("%s: Failed due to size(%#lx) @ %#x is"\
> > + " smaller than page size %#x\n",
> > + __func__, iova, size, err_page);
>
> Aren't iova and size arguments interchanged here?
Oh, it is my mistake.
It will should be fixed in the next patchset with the change in
calculation of err_page.
>
> > +
> > + return 0;
>
> There is an intendation issue here (extra whitespaces).
Yes. Thanks.
>
> > +
> > }
> >
> > static phys_addr_t exynos_iommu_iova_to_phys(struct iommu_domain *domain,
>
> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
Thank you.
Cho KyongHo.
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