by Yong Wu (吴勇)

[permalink] [raw]

Subject: Re: [PATCH v2 3/6] iommu: add ARM short descriptor page table allocator.

Hi Will,
Thanks very much for your review.
Sorry for reply so late, I need some time to test the split.
I will improve in next version following your suggestion.
There are some place please help check my comment.

On Fri, 2015-06-05 at 14:12 +0100, Will Deacon wrote:
> Hello,
>
> Thanks for the patch, it's good to see another user of the generic
> IO page-table code. However, I have quite a lot of comments on the code.
>
> On Fri, May 15, 2015 at 10:43:26AM +0100, Yong Wu wrote:
> > This patch is for ARM Short Descriptor Format.It has 2-levels
> > pagetable and the allocator supports 4K/64K/1M/16M.
> >
> > Signed-off-by: Yong Wu <[email protected]>
> > ---
> > drivers/iommu/Kconfig | 7 +
> > drivers/iommu/Makefile | 1 +
> > drivers/iommu/io-pgtable-arm-short.c | 490 +++++++++++++++++++++++++++++++++++
> > drivers/iommu/io-pgtable.c | 4 +
> > drivers/iommu/io-pgtable.h | 6 +
> > 5 files changed, 508 insertions(+)
> > create mode 100644 drivers/iommu/io-pgtable-arm-short.c
>
> For some reason, I ended up reviewing this back-to-front (i.e. starting
> with the init code), so apologies if the comments feel like they were
> written in reverse.
>
[snip]
> > +typedef u32 arm_short_iopte;
> > +
> > +struct arm_short_io_pgtable {
> > + struct io_pgtable iop;
> > + struct kmem_cache *ptekmem;
> > + size_t pgd_size;
> > + void *pgd;
> > +};
> > +
> > +#define io_pgtable_short_to_data(x) \
> > + container_of((x), struct arm_short_io_pgtable, iop)
> > +
> > +#define io_pgtable_ops_to_pgtable(x) \
> > + container_of((x), struct io_pgtable, ops)
> > +
> > +#define io_pgtable_short_ops_to_data(x) \
> > + io_pgtable_short_to_data(io_pgtable_ops_to_pgtable(x))
> > +
>
> These are private macros, so I think you can drop the "short" part to,
> err, keep them short.

I will delete "short" in the definitions.

And io_pgtable_ops_to_pgtable is same with the one in LPAE.
How about move it to alongside the definition of struct io_pgtable in
io-pgtable.h and also delete it in io-pgtable-arm.c?.

> > +#define ARM_SHORT_MAX_ADDR_BITS 32
> > +
> > +#define ARM_SHORT_PGDIR_SHIFT 20
> > +#define ARM_SHORT_PAGE_SHIFT 12
> > +#define ARM_SHORT_PTRS_PER_PTE 256
> > +#define ARM_SHORT_BYTES_PER_PTE 1024
>
> Isn't that ARM_SHORT_PTRS_PER_PTE * sizeof(arm_short_iopte)?
>
> > +/* 1 level pagetable */
> > +#define ARM_SHORT_F_PGD_TYPE_PAGE (0x1)
>
> I think you're using PAGE and PGTABLE interchangeably, which is really
> confusing to read.
>
> > +#define ARM_SHORT_F_PGD_TYPE_PAGE_MSK (0x3)
>
> This is the TYPE mask.
>
> > +#define ARM_SHORT_F_PGD_TYPE_SECTION (0x2)
> > +#define ARM_SHORT_F_PGD_TYPE_SUPERSECTION (0x2 | (1 << 18))
>
> Are you sure this is correct? afaict, bit 0 is PXN, so you should actually
> be using bit 18 to distinguihs sections and supersections.
Thanks.
I will change all like this, is it ok?
//===
#define ARM_SHORT_PGD_TYPE_PGTABLE BIT(0)
#define ARM_SHORT_PGD_TYPE_SECTION BIT(1)
#define ARM_SHORT_PGD_B_BIT BIT(2)
#define ARM_SHORT_PGD_C_BIT BIT(3)
#define ARM_SHORT_PGD_NS_PGTABLE_BIT BIT(3)
#define ARM_SHORT_PGD_IMPLE_BIT BIT(9)
#define ARM_SHORT_PGD_TEX0_BIT BIT(12)
#define ARM_SHORT_PGD_S_BIT BIT(16)
#define ARM_SHORT_PGD_SUPERSECTION_BIT BIT(18)
#define ARM_SHORT_PGD_NS_SECTION_BIT BIT(19)

#define ARM_SHORT_PGD_TYPE_SUPERSECTION \
(ARM_SHORT_PGD_TYPE_SECTION | ARM_SHORT_PGD_SUPERSECTION_BIT)
#define ARM_SHORT_PGD_PGTABLE_MSK (0x3)
#define ARM_SHORT_PGD_SECTION_MSK \
(ARM_SHORT_PGD_PGTABLE_MSK | ARM_SHORT_PGD_SUPERSECTION_BIT)
//=====

> > +#define ARM_SHORT_F_PGD_TYPE_SECTION_MSK (0x3 | (1 << 18))
> > +#define ARM_SHORT_F_PGD_TYPE_IS_PAGE(pgd) (((pgd) & 0x3) == 1)
>
> Use your TYPE mask here.
>
> > +#define ARM_SHORT_F_PGD_TYPE_IS_SECTION(pgd) \
> > + (((pgd) & ARM_SHORT_F_PGD_TYPE_SECTION_MSK) \
> > + == ARM_SHORT_F_PGD_TYPE_SECTION)
> > +#define ARM_SHORT_F_PGD_TYPE_IS_SUPERSECTION(pgd) \
> > + (((pgd) & ARM_SHORT_F_PGD_TYPE_SECTION_MSK) \
> > + == ARM_SHORT_F_PGD_TYPE_SUPERSECTION)
> > +
> > +#define ARM_SHORT_F_PGD_B_BIT BIT(2)
> > +#define ARM_SHORT_F_PGD_C_BIT BIT(3)
> > +#define ARM_SHORT_F_PGD_IMPLE_BIT BIT(9)
> > +#define ARM_SHORT_F_PGD_S_BIT BIT(16)
> > +#define ARM_SHORT_F_PGD_NG_BIT BIT(17)
> > +#define ARM_SHORT_F_PGD_NS_BIT_PAGE BIT(3)
> > +#define ARM_SHORT_F_PGD_NS_BIT_SECTION BIT(19)
> > +
> > +#define ARM_SHORT_F_PGD_PA_PAGETABLE_MSK 0xfffffc00
> > +#define ARM_SHORT_F_PGD_PA_SECTION_MSK 0xfff00000
> > +#define ARM_SHORT_F_PGD_PA_SUPERSECTION_MSK 0xff000000
> > +
[snip]
> > +static int _arm_short_check_free_pte(struct arm_short_io_pgtable *data,
> > + arm_short_iopte *pgd)
> > +{
> > + arm_short_iopte *pte;
> > + int i;
> > +
> > + pte = ARM_SHORT_GET_PTE_VA(*pgd);
> > +
> > + for (i = 0; i < ARM_SHORT_PTRS_PER_PTE; i++) {
> > + if (pte[i] != 0)
> > + return 1;
>
> -EEXIST?
>
> > + }
> > +
> > + /* Free PTE */
> > + kmem_cache_free(data->ptekmem, pte);
> > + *pgd = 0;
>
> I don't think this is safe, as there's a window where the page table
> walker can see the freed pte memory.

Sorry, this function read badly. Originally I expected this function
could check all the ptes in the level-2 pagetable.
I prepare to change the function name and the return type like below,
if all the pte is 0, then free whole the level-2 pagetable and return
true, if there are some other pte remain who isn't unmapped, it return
false.
static bool arm_short_free_wholepte(struct arm_short_io_pgtable *data,
arm_short_iopte *pgd)

> > +
> > + return 0;
> > +}
> > +
> > +static int arm_short_unmap(struct io_pgtable_ops *ops, unsigned long iova,
> > + size_t size)
> > +{
> > + struct arm_short_io_pgtable *data = io_pgtable_short_ops_to_data(ops);
> > + arm_short_iopte *pgd;
> > + unsigned long iova_start = iova;
> > + unsigned long long end_plus_1 = iova + size;
> > + const struct iommu_gather_ops *tlb = data->iop.cfg.tlb;
> > + void *cookie = data->iop.cookie;
> > + int ret;
> > +
> > + do {
> > + pgd = (arm_short_iopte *)data->pgd + ARM_SHORT_PGD_IDX(iova);
> > +
> > + if (ARM_SHORT_F_PGD_TYPE_IS_PAGE(*pgd)) {
> > + arm_short_iopte *pte;
> > + unsigned int pte_offset;
> > + unsigned int num_to_clean;
> > +
> > + pte_offset = ARM_SHORT_PTE_IDX(iova);
> > + num_to_clean =
> > + min((unsigned int)((end_plus_1 - iova) / PAGE_SIZE),
> > + (ARM_SHORT_PTRS_PER_PTE - pte_offset));
> > +
> > + pte = arm_short_get_pte_in_pgd(*pgd, iova);
> > +
> > + memset(pte, 0, num_to_clean * sizeof(arm_short_iopte));
> > +
> > + ret = _arm_short_check_free_pte(data, pgd);
> > + if (ret == 1)/* pte is not freed, need to flush pte */
> > + tlb->flush_pgtable(
> > + pte,
> > + num_to_clean * sizeof(arm_short_iopte),
> > + cookie);
> > + else
> > + tlb->flush_pgtable(pgd, sizeof(arm_short_iopte),
> > + cookie);
>
> Hopefully this can be cleaned up when you remove the outer loop and you
> can use the size parameter to figure out which level to unmap.
>
> > + iova += num_to_clean << PAGE_SHIFT;
> > + } else if (ARM_SHORT_F_PGD_TYPE_IS_SECTION(*pgd)) {
> > + *pgd = 0;
> > +
> > + tlb->flush_pgtable(pgd, sizeof(arm_short_iopte),
> > + cookie);
> > + iova += SZ_1M;
>
> Again, these sizes can be derived from other page table properties that
> you have.
>
> > + } else if (ARM_SHORT_F_PGD_TYPE_IS_SUPERSECTION(*pgd)) {
> > + arm_short_iopte *start;
> > +
> > + start = arm_short_supersection_start(pgd);
> > + if (unlikely(start != pgd))
> > + pr_warn("%s:suppersection start isn't aligned.iova=0x%lx,pgd=0x%x\n",
> > + __func__, iova, *pgd);
> > +
> > + memset(start, 0, 16 * sizeof(arm_short_iopte));
> > +
> > + tlb->flush_pgtable(start, 16 * sizeof(arm_short_iopte),
> > + cookie);
> > +
> > + iova = (iova + SZ_16M) & (~(SZ_16M - 1));
>
> See later, but I think supersections should not be assumed by default.
>
> > + } else {
> > + break;
> > + }
> > + } while (iova < end_plus_1 && iova);
>
> I don't think you need this loop -- unmap will be called in page-sized
> chunks (where page-size refers to units as advertised in your IOMMU's
> pgsize_bitmap). The tricky part is when somebody unmaps a subset of a
> previous mapping that ended up using something like a section. You need
> to handle that here by splitting blocks at level 1 into a table and
> allocating a level 2.

I will delete the loop and get the size from the pagetable properties.
About the split, I have a question,
There are some lines in the self test of LPAE:
//====
/* Partial unmap */
size = 1UL << __ffs(cfg->pgsize_bitmap);
if (ops->unmap(ops, SZ_1G + size, size) != size)
return __FAIL(ops, i);
//====
If it is changed to:
if (ops->unmap(ops, SZ_1G + 3*size, size) != size)
or
if (ops->unmap(ops, SZ_1G + size, 3*size) != size)
It seems don't work. I think it may be never happened if the map and
unmap is from iommu_map and iommu_unmap, I don't know whether somebody
will unmap subset of a previous mapping randomly like above. so I am
sure whether I should cover this two cases in short-descriptor.

>
> > +
> > + tlb->tlb_add_flush(iova_start, size, true, cookie);
> > +
> > + return 0;
>
> You need to return the size of the region that you managed to unmap, so
> 0 isn't right here.
>
> > +}
> > +
> > +static arm_short_iopte __arm_short_pte_port(unsigned int prot, bool large)
> > +{
> > + arm_short_iopte pteprot;
> > +
> > + pteprot = ARM_SHORT_F_PTE_S_BIT;
> > +
> > + pteprot |= large ? ARM_SHORT_F_PTE_TYPE_LARGE :
> > + ARM_SHORT_F_PTE_TYPE_SMALL;
> > +
> > + if (prot & IOMMU_CACHE)
> > + pteprot |= ARM_SHORT_F_PTE_B_BIT | ARM_SHORT_F_PTE_C_BIT;
>
> Where do you set TEX[0] for write-allocate?
I will add:
if (prot & IOMMU_WRITE)
pteprot |= ARM_SHORT_PTE_TEX0_BIT;
>
> > + return pteprot;
> > +}
> > +
> > +static arm_short_iopte __arm_short_pgd_port(int prot, bool super)
> > +{
> > + arm_short_iopte pgdprot;
> > +
> > + pgdprot = ARM_SHORT_F_PGD_S_BIT;
> > + pgdprot |= super ? ARM_SHORT_F_PGD_TYPE_SUPERSECTION :
> > + ARM_SHORT_F_PGD_TYPE_SECTION;
> > + if (prot & IOMMU_CACHE)
> > + pgdprot |= ARM_SHORT_F_PGD_C_BIT | ARM_SHORT_F_PGD_B_BIT;
> > +
> > + return pgdprot;
> > +}
> > +
> > +static int _arm_short_map_page(struct arm_short_io_pgtable *data,
> > + unsigned int iova, phys_addr_t pa,
> > + unsigned int prot, bool largepage)
> > +{
> > + arm_short_iopte *pgd = data->pgd;
> > + arm_short_iopte *pte;
> > + arm_short_iopte pgdprot, pteprot;
> > + arm_short_iopte mask = largepage ? ARM_SHORT_F_PTE_PA_LARGE_MSK :
> > + ARM_SHORT_F_PTE_PA_SMALL_MSK;
> > + int i, ptenum = largepage ? 16 : 1;
> > + bool ptenew = false;
> > + void *pte_new_va;
> > + void *cookie = data->iop.cookie;
> > +
> > + if ((iova | pa) & (~mask)) {
> > + pr_err("IOVA|PA Not Aligned(iova=0x%x pa=0x%pa type=%s)\n",
> > + iova, &pa, largepage ? "large page" : "small page");
> > + return -EINVAL;
> > + }
> > +
> > + pgdprot = ARM_SHORT_F_PGD_TYPE_PAGE;
> > + if (data->iop.cfg.quirks & IO_PGTABLE_QUIRK_ARM_NS)
> > + pgdprot |= ARM_SHORT_F_PGD_NS_BIT_PAGE;
> > +
> > + pgd += ARM_SHORT_PGD_IDX(iova);
> > +
> > + if (!(*pgd)) {
> > + pte_new_va = kmem_cache_zalloc(data->ptekmem, GFP_KERNEL);
> > + if (unlikely(!pte_new_va)) {
> > + pr_err("Failed to alloc pte\n");
> > + return -ENOMEM;
> > + }
> > +
> > + /* Check pte alignment -- must 1K align */
> > + if (unlikely((unsigned long)pte_new_va &
> > + (ARM_SHORT_BYTES_PER_PTE - 1))) {
> > + pr_err("The new pte is not aligned! (va=0x%p)\n",
> > + pte_new_va);
> > + kmem_cache_free(data->ptekmem, (void *)pte_new_va);
> > + return -ENOMEM;
> > + }
>
> How are you enforcing this alignment?

I will delete this.

>
> > + ptenew = true;
> > + *pgd = virt_to_phys(pte_new_va) | pgdprot;
> > + kmemleak_ignore(pte_new_va);
>
> Maybe you should be using alloc_pages instead of your kmem_cache (I mention
> this again later on).
>
> > + data->iop.cfg.tlb->flush_pgtable(pgd, sizeof(arm_short_iopte),
> > + cookie);
> > + } else {
> > + /* Someone else may have allocated for this pgd */
> > + if (((*pgd) & (~ARM_SHORT_F_PGD_PA_PAGETABLE_MSK)) != pgdprot) {
> > + pr_err("The prot of old pgd is not Right!iova=0x%x pgd=0x%x pgprot=0x%x\n",
> > + iova, (*pgd), pgdprot);
>
> You can probably just WARN here, as I do in the LPAE code. It shows a bug
> in the caller of the API.
Sorry, I don't see it in LPAE, Do you mean these lines in LPAE?
//====
/* We require an unmap first */
if (iopte_leaf(*ptep, lvl)) {
WARN_ON(!selftest_running);
return -EEXIST;
}
//====
It may be not the same. Here we only check whether the prot of the old
pgd is same with the current pgd.
I will change it to WARN_ON(1) too.
>
> > + return -EEXIST;
> > + }
> > + }
> > +
> > + pteprot = (arm_short_iopte)pa;
> > + pteprot |= __arm_short_pte_port(prot, largepage);
> > +
> > + pte = arm_short_get_pte_in_pgd(*pgd, iova);
> > +
> > + pr_debug("iova:0x%x,pte:0x%p(0x%x),prot:0x%x-%s\n",
> > + iova, pte, ARM_SHORT_PTE_IDX(iova), pteprot,
> > + largepage ? "large page" : "small page");
> > +
> > + for (i = 0; i < ptenum; i++) {
> > + if (pte[i]) {
> > + pr_err("The To-Map pte exists!(iova=0x%x pte=0x%x i=%d)\n",
> > + iova, pte[i], i);
> > + goto err_out;
I will change to WARN_ON(1) here too.
> > + }
> > + pte[i] = pteprot;
> > + }
>
> I don't think you need this loop; you should only be given a page size,
> like with unmap.

I am not sure I follow your meaning.The ptenum here is only 1 or 16.
It is 1 while current is small page and section. It is 16 while current
is large page or super section.
Because the descriptor should be repeated 16 consecutive, I use a loop
here.
>
> > +
> > + data->iop.cfg.tlb->flush_pgtable(pte, ptenum * sizeof(arm_short_iopte),
> > + cookie);
> > + return 0;
> > +
> > + err_out:
> > + for (i--; i >= 0; i--)
> > + pte[i] = 0;
> > + if (ptenew)
> > + kmem_cache_free(data->ptekmem, pte_new_va);
> > + return -EEXIST;
> > +}
> > +
> > +static int _arm_short_map_section(struct arm_short_io_pgtable *data,
> > + unsigned int iova, phys_addr_t pa,
> > + int prot, bool supersection)
> > +{
> > + arm_short_iopte pgprot;
> > + arm_short_iopte mask = supersection ?
> > + ARM_SHORT_F_PGD_PA_SUPERSECTION_MSK :
> > + ARM_SHORT_F_PGD_PA_SECTION_MSK;
> > + arm_short_iopte *pgd = data->pgd;
> > + int i;
> > + unsigned int pgdnum = supersection ? 16 : 1;
> > +
> > + if ((iova | pa) & (~mask)) {
> > + pr_err("IOVA|PA Not Aligned(iova=0x%x pa=0x%pa type=%s)\n",
> > + iova, &pa, supersection ? "supersection" : "section");
> > + return -EINVAL;
> > + }
> > +
> > + pgprot = (arm_short_iopte)pa;
> > +
> > + if (data->iop.cfg.quirks & IO_PGTABLE_QUIRK_ARM_NS)
> > + pgprot |= ARM_SHORT_F_PGD_NS_BIT_SECTION;
> > +
> > + pgprot |= __arm_short_pgd_port(prot, supersection);
> > +
> > + pgd += ARM_SHORT_PGD_IDX(iova);
> > +
> > + pr_debug("iova:0x%x,pgd:0x%p(0x%p+0x%x),value:0x%x-%s\n",
> > + iova, pgd, data->pgd, ARM_SHORT_PGD_IDX(iova),
> > + pgprot, supersection ? "supersection" : "section");
> > +
> > + for (i = 0; i < pgdnum; i++) {
> > + if (unlikely(*pgd)) {
> > + pr_err("The To-Map pdg exists!(iova=0x%x pgd=0x%x i=%d)\n",
> > + iova, pgd[i], i);
> > + goto err_out;
> > + }
> > + pgd[i] = pgprot;
> > + }
>
> Similar comments here.
I will merge _arm_short_map_page and _arm_short_map_section into one
function named _arm_short_map.
>
> > + data->iop.cfg.tlb->flush_pgtable(pgd,
> > + pgdnum * sizeof(arm_short_iopte),
> > + data->iop.cookie);
> > + return 0;
> > +
> > + err_out:
> > + for (i--; i >= 0; i--)
> > + pgd[i] = 0;
> > + return -EEXIST;
> > +}
> > +
> > +static int arm_short_map(struct io_pgtable_ops *ops, unsigned long iova,
> > + phys_addr_t paddr, size_t size, int prot)
> > +{
> > + struct arm_short_io_pgtable *data = io_pgtable_short_ops_to_data(ops);
> > + const struct iommu_gather_ops *tlb = data->iop.cfg.tlb;
> > + int ret;
> > +
> > + if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
> > + return -EINVAL;
>
> Why? You could have (another) quirk to select the access model and you
> should be able to implement read+write, read-only no-exec and no-access.

If I follow it in LAPE like below. is it ok?
//======
/* If no access, then nothing to do */
if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
return 0;
//=====
>
> > + if (size == SZ_4K) {/* most case */
> > + ret = _arm_short_map_page(data, iova, paddr, prot, false);
> > + } else if (size == SZ_64K) {
> > + ret = _arm_short_map_page(data, iova, paddr, prot, true);
> > + } else if (size == SZ_1M) {
> > + ret = _arm_short_map_section(data, iova, paddr, prot, false);
> > + } else if (size == SZ_16M) {
> > + ret = _arm_short_map_section(data, iova, paddr, prot, true);
> > + } else {
> > + ret = -EINVAL;
> > + }
>
> Use a switch statement here?
>
> > + tlb->tlb_add_flush(iova, size, true, data->iop.cookie);
> > + return ret;
> > +}
> > +
> > +static struct io_pgtable *
> > +arm_short_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
> > +{
> > + struct arm_short_io_pgtable *data;
> > +
> > + if (cfg->ias != 32)
> > + return NULL;
>
> I think you just need to check '>'; VAs smaller than 32-bit can still
> be translated.
>
> > + if (cfg->oas > ARM_SHORT_MAX_ADDR_BITS)
> > + return NULL;
>
> What benefit does ARM_SHORT_MAX_ADDR_BITS offer? Why not just '32'?
>
> > +
> > + cfg->pgsize_bitmap &= SZ_4K | SZ_64K | SZ_1M | SZ_16M;
>
> We can't support supersections unconditionally. Please add a quirk for
> this, as it relies on IOMMU support.
>
> > + data = kzalloc(sizeof(*data), GFP_KERNEL);
> > + if (!data)
> > + return NULL;
> > +
> > + data->pgd_size = SZ_16K;
> > +
> > + data->pgd = alloc_pages_exact(data->pgd_size, GFP_KERNEL | __GFP_ZERO);
> > + if (!data->pgd)
> > + goto out_free_data;
> > +
> > + cfg->tlb->flush_pgtable(data->pgd, data->pgd_size, cookie);
>
> We may as well postpone this flush to the end of the function, given that
> we can still fail at this point.
>
> > + /* kmem for pte */
> > + data->ptekmem = kmem_cache_create("short-descriptor-pte",
>
> A better name would be "io-pgtable-arm-short", however, why can't you
> just use GFP_ATOMIC in your pte allocations and do away with the cache
> altogether? Also, what happens if you try to allocate multiple caches
> with the same name?
I will add GFP_ATOMIC in pte allocation, It is a bug Daniel has help
to fix it.
And I am sorry. I don't know what is wrong if using kmem_cache here.
The main reason is the size. the size of level-2 pgtable is 1KB, and
the alloc_page_exact will be 4KB. so I use kmem_cache here.
>
> > + ARM_SHORT_BYTES_PER_PTE,
> > + ARM_SHORT_BYTES_PER_PTE,
> > + 0, NULL);
> > +
> > + if (IS_ERR_OR_NULL(data->ptekmem)) {
>
> I think you just need a NULL check here.
>
> > + pr_err("Failed to Create cached mem for PTE %ld\n",
> > + PTR_ERR(data->ptekmem));
>
> I don't think this error is particularly useful.
>
> > + goto out_free_pte;
> > + }
> > +
> > + /* TTBRs */
> > + cfg->arm_short_cfg.ttbr[0] = virt_to_phys(data->pgd);
> > + cfg->arm_short_cfg.ttbr[1] = 0;
> > +
> > + cfg->arm_short_cfg.tcr = 0;
> > +
> > + data->iop.ops = (struct io_pgtable_ops) {
> > + .map = arm_short_map,
> > + .unmap = arm_short_unmap,
> > + .iova_to_phys = arm_short_iova_to_phys,
> > + };
> > +
> > + return &data->iop;
> > +
> > +out_free_pte:
> > + free_pages_exact(data->pgd, data->pgd_size);
> > +out_free_data:
> > + kfree(data);
> > + return NULL;
> > +}
> > +
> > +static void arm_short_free_pgtable(struct io_pgtable *iop)
> > +{
> > + struct arm_short_io_pgtable *data = io_pgtable_short_to_data(iop);
> > +
> > + kmem_cache_destroy(data->ptekmem);
> > + free_pages_exact(data->pgd, data->pgd_size);
> > + kfree(data);
> > +}
> > +
> > +struct io_pgtable_init_fns io_pgtable_arm_short_init_fns = {
> > + .alloc = arm_short_alloc_pgtable,
> > + .free = arm_short_free_pgtable,
> > +};
> > +
> > diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
> > index 6436fe2..14a9b3a 100644
> > --- a/drivers/iommu/io-pgtable.c
> > +++ b/drivers/iommu/io-pgtable.c
> > @@ -28,6 +28,7 @@ extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns;
> > extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s2_init_fns;
> > extern struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns;
> > extern struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns;
> > +extern struct io_pgtable_init_fns io_pgtable_arm_short_init_fns;
> >
> > static const struct io_pgtable_init_fns *
> > io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] =
> > @@ -38,6 +39,9 @@ io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] =
> > [ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns,
> > [ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns,
> > #endif
> > +#ifdef CONFIG_IOMMU_IO_PGTABLE_SHORT
> > + [ARM_SHORT_DESC] = &io_pgtable_arm_short_init_fns,
> > +#endif
> > };
> >
> > struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
> > diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
> > index 10e32f6..47efaab 100644
> > --- a/drivers/iommu/io-pgtable.h
> > +++ b/drivers/iommu/io-pgtable.h
> > @@ -9,6 +9,7 @@ enum io_pgtable_fmt {
> > ARM_32_LPAE_S2,
> > ARM_64_LPAE_S1,
> > ARM_64_LPAE_S2,
> > + ARM_SHORT_DESC,
> > IO_PGTABLE_NUM_FMTS,
> > };
> >
> > @@ -62,6 +63,11 @@ struct io_pgtable_cfg {
> > u64 vttbr;
> > u64 vtcr;
> > } arm_lpae_s2_cfg;
> > +
> > + struct {
> > + u64 ttbr[2];
> > + u64 tcr;
> > + } arm_short_cfg;
>
> I appreciate that you're not using TEX remapping, but could we include
> the NMRR and PRRR registers here (we can just zero them) too, please?
> That makes it easier to support a TEX_REMAP quick later on and also sets
> them to a known value.
I will add them and set 0 to them.
u32 ttbr[2];
u32 tcr;
+ u32 nmrr;
+ u32 prrr;
And According to Robin's suggestion, I will change to u32 in
short-descriptor.
>
> Also, any chance of some self-tests?
>
> Will