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Message-ID: <1442931167.17514.39.camel@mhfsdcap03>
Date: Tue, 22 Sep 2015 22:12:47 +0800
From: Yong Wu <yong.wu@...iatek.com>
To: Will Deacon <will.deacon@....com>,
Robin Murphy <Robin.Murphy@....com>
CC: Mark Rutland <Mark.Rutland@....com>,
Catalin Marinas <Catalin.Marinas@....com>,
"youhua.li@...iatek.com" <youhua.li@...iatek.com>,
Thierry Reding <treding@...dia.com>,
"k.zhang@...iatek.com" <k.zhang@...iatek.com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"arnd@...db.de" <arnd@...db.de>, Tomasz Figa <tfiga@...gle.com>,
Rob Herring <robh+dt@...nel.org>,
"linux-mediatek@...ts.infradead.org"
<linux-mediatek@...ts.infradead.org>,
Matthias Brugger <matthias.bgg@...il.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"pebolle@...cali.nl" <pebolle@...cali.nl>,
"frederic.chen@...iatek.com" <frederic.chen@...iatek.com>,
"srv_heupstream@...iatek.com" <srv_heupstream@...iatek.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
Daniel Kurtz <djkurtz@...gle.com>,
Sasha Hauer <kernel@...gutronix.de>,
Lucas Stach <l.stach@...gutronix.de>
Subject: Re: [PATCH v4 3/6] iommu: add ARM short descriptor page table
allocator.
> > > +static int arm_short_unmap(struct io_pgtable_ops *ops,
> > > + unsigned long iova,
> > > + size_t size)
> > > +{
> > > + struct arm_short_io_pgtable *data = io_pgtable_ops_to_data(ops);
> > > + struct io_pgtable_cfg *cfg = &data->iop.cfg;
> > > + arm_short_iopte *pgd, *pte = NULL;
> > > + arm_short_iopte curpgd, curpte = 0;
> > > + phys_addr_t paddr;
> > > + unsigned int iova_base, blk_size = 0;
> > > + void *cookie = data->iop.cookie;
> > > + bool pgtablefree = false;
> > > +
> > > + pgd = (arm_short_iopte *)data->pgd + ARM_SHORT_PGD_IDX(iova);
> > > +
> > > + /* Get block size */
> > > + if (ARM_SHORT_PGD_TYPE_IS_PGTABLE(*pgd)) {
> > > + pte = arm_short_get_pte_in_pgd(*pgd, iova);
> > > +
> > > + if (ARM_SHORT_PTE_TYPE_IS_SMALLPAGE(*pte))
> > > + blk_size = SZ_4K;
> > > + else if (ARM_SHORT_PTE_TYPE_IS_LARGEPAGE(*pte))
> > > + blk_size = SZ_64K;
> > > + else
> > > + WARN_ON(1);
>
> > > + } else if (ARM_SHORT_PGD_TYPE_IS_SECTION(*pgd)) {
> > > + blk_size = SZ_1M;
> > > + } else if (ARM_SHORT_PGD_TYPE_IS_SUPERSECTION(*pgd)) {
> > > + blk_size = SZ_16M;
> > > + } else {
> > > + WARN_ON(1);
> > > + }
> > > +
> > > + iova_base = iova & ~(blk_size - 1);
> > > + pgd = (arm_short_iopte *)data->pgd + ARM_SHORT_PGD_IDX(iova_base);
> > > + paddr = arm_short_iova_to_phys(ops, iova_base);
> > > + curpgd = *pgd;
> > > +
> > > + if (blk_size == SZ_4K || blk_size == SZ_64K) {
> > > + pte = arm_short_get_pte_in_pgd(*pgd, iova_base);
> > > + curpte = *pte;
> > > + __arm_short_set_pte(pte, 0, blk_size / SZ_4K, cfg);
> > > +
> > > + pgtablefree = _arm_short_whether_free_pgtable(pgd);
> > > + if (pgtablefree)
> > > + __arm_short_set_pte(pgd, 0, 1, cfg);
> > > + } else if (blk_size == SZ_1M || blk_size == SZ_16M) {
> > > + __arm_short_set_pte(pgd, 0, blk_size / SZ_1M, cfg);
> > > + }
> > > +
> > > + cfg->tlb->tlb_add_flush(iova_base, blk_size, true, cookie);
> > > + cfg->tlb->tlb_sync(cookie);
> > > +
> > > + if (pgtablefree)/* Free pgtable after tlb-flush */
> > > + __arm_short_free_pgtable(ARM_SHORT_GET_PGTABLE_VA(curpgd),
> > > + ARM_SHORT_BYTES_PER_PTE, false, cfg);
> > > +
> > > + if (blk_size > size) { /* Split the block */
> > > + return arm_short_split_blk_unmap(
> > > + ops, iova, paddr, size,
> > > + ARM_SHORT_PGD_GET_PROT(curpgd),
> > > + ARM_SHORT_PTE_LARGE_GET_PROT(curpte),
> > > + blk_size);
> > > + } else if (blk_size < size) {
> > > + /* Unmap the block while remap partial again after split */
> > > + return blk_size +
> > > + arm_short_unmap(ops, iova + blk_size, size - blk_size);
Hi Will, Robin,
I would like to show you a problem I met, The recursion here may
lead to stack overflow while we test FHD video decode.
From the log, I get the internal variable in the error case: the
"size" is 0x100000, the "iova" is 0xfea00000, but at that time the
"blk_size" is 0x1000 as it was the map of small-page. so it enter the
recursion here.
After check the unmap flow, there is only a iommu_unmap in
__iommu_dma_unmap, and it won't check the physical address align in
iommu_unmap.
so if the iova and size both are SZ_16M or SZ_1M align by chance, it
also enter the arm_short_unmap even though it was the map of small-page.
So.
a) Do we need unmap each sg item while iommu_dma_unmap?, like below:
//===============
static void __iommu_dma_unmap(struct iommu_domain *domain, dma_addr_t
dma_addr)
{
/* ...and if we can't, then something is horribly, horribly wrong */
+ for_each_sg(sg, s, nents, i)
BUG_ON(iommu_unmap(domain, pfn << shift, size) < size);
__free_iova(iovad, iova);
}
//===============
b). I need to add do-while which was suggested to delete from [1] in
arm_short_unmap for this case.
After I test locally, I prepare to add the do-while like below:
//==============================
static int arm_short_unmap(struct io_pgtable_ops *ops,
unsigned long iova,
size_t size)
{
struct arm_short_io_pgtable *data = io_pgtable_ops_to_data(ops);
struct io_pgtable_cfg *cfg = &data->iop.cfg;
arm_short_iopte *pgd, *pte = NULL;
arm_short_iopte curpgd, curpte = 0;
unsigned int blk_base, blk_size;
int unmap_size = 0;
bool pgtempty;
do {
pgd = (arm_short_iopte *)data->pgd + ARM_SHORT_PGD_IDX(iova);
blk_size = 0;
pgtempty = false;
/* Get block size */
if (ARM_SHORT_PGD_TYPE_IS_PGTABLE(*pgd)) {
pte = arm_short_get_pte_in_pgd(*pgd, iova);
if (ARM_SHORT_PTE_TYPE_IS_SMALLPAGE(*pte))
blk_size = SZ_4K;
else if (ARM_SHORT_PTE_TYPE_IS_LARGEPAGE(*pte))
blk_size = SZ_64K;
} else if (ARM_SHORT_PGD_TYPE_IS_SECTION(*pgd)) {
blk_size = SZ_1M;
} else if (ARM_SHORT_PGD_TYPE_IS_SUPERSECTION(*pgd)) {
blk_size = SZ_16M;
}
if (WARN_ON(!blk_size))
return 0;
blk_base = iova & ~(blk_size - 1);
pgd = (arm_short_iopte *)data->pgd + ARM_SHORT_PGD_IDX(blk_base);
curpgd = *pgd;
if (blk_size == SZ_4K || blk_size == SZ_64K) {
pte = arm_short_get_pte_in_pgd(*pgd, blk_base);
curpte = *pte;
__arm_short_set_pte(pte, 0, blk_size / SZ_4K, cfg);
pgtempty = __arm_short_pgtable_empty(pgd);
if (pgtempty)
__arm_short_set_pte(pgd, 0, 1, cfg);
} else if (blk_size == SZ_1M || blk_size == SZ_16M) {
__arm_short_set_pte(pgd, 0, blk_size / SZ_1M, cfg);
}
cfg->tlb->tlb_add_flush(blk_base, blk_size, true, data->iop.cookie);
cfg->tlb->tlb_sync(data->iop.cookie);
if (pgtempty)/* Free lvl2 pgtable after tlb-flush */
__arm_short_free_pgtable(
ARM_SHORT_GET_PGTABLE_VA(curpgd),
ARM_SHORT_BYTES_PER_PTE, false, cfg);
/*
* If the unmap size which is from the pgsize_bitmap is more
* than the current blk_size, unmap it continuously.
*/
if (blk_size <= size) {
iova += blk_size;
size -= blk_size;
unmap_size += blk_size;
continue;
} else { /* Split this block */
return arm_short_split_blk_unmap(
ops, iova, size, blk_size,
ARM_SHORT_PGD_GET_PROT(curpgd),
ARM_SHORT_PTE_GET_PROT_LARGE(curpte));
}
}while (size);
return unmap_size;
}
//=============================
Is there any other suggestion?
Thanks very much.
[1]:http://lists.linuxfoundation.org/pipermail/iommu/2015-June/013322.html
> > > + }
> > > +
> > > + return size;
> > > +}
> > > +
> _______________________________________________
> iommu mailing list
> iommu@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
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