Hi Robin,
Thanks very much for so detail suggestion.
please also help check my comment, the others i will change in next
time.
On Fri, 2015-05-15 at 16:30 +0100, Robin Murphy wrote:
> Oops, seems I'm rather behind on things - I started this review on the
> RFC, but I'll finish it here...
>
> On 15/05/15 10:43, Yong Wu wrote:
> > This patch is for ARM Short Descriptor Format.It has 2-levels
> > pagetable and the allocator supports 4K/64K/1M/16M.
> >
>
> From the look of the code, this doesn't fully support partial unmaps
> (i.e. splitting block entries), am I right? That's OK for DMA-API use,
> since that doesn't permit partial unmaps anyway, but I'd say it's worth
> making it clear that that's still a TODO in order for short-descriptor
> mappings to fully support arbitrary raw IOMMU API usage.
Yes. I don't add split right now due to I check that
iommu_map/iommu_unmap make sure iova|pa be aligned.
I will add split for fully support in next version. Thanks.
>
> > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> > ---
> > 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
> >
> > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> > index 1ae4e54..3d2eac6 100644
> > --- a/drivers/iommu/Kconfig
> > +++ b/drivers/iommu/Kconfig
> > @@ -39,6 +39,13 @@ config IOMMU_IO_PGTABLE_LPAE_SELFTEST
> >
> > If unsure, say N here.
> >
> > +config IOMMU_IO_PGTABLE_SHORT
> > + bool "ARMv7/v8 Short Descriptor Format"
> > + select IOMMU_IO_PGTABLE
> > + help
> > + Enable support for the ARM Short descriptor pagetable format.
> > + It has 2-levels pagetable and The allocator supports 4K/64K/1M/16M.
> > +
> > endmenu
> >
> > config IOMMU_IOVA
> > diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> > index 080ffab..815b3c8 100644
> > --- a/drivers/iommu/Makefile
> > +++ b/drivers/iommu/Makefile
> > @@ -3,6 +3,7 @@ obj-$(CONFIG_IOMMU_API) += iommu-traces.o
> > obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
> > obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
> > obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
> > +obj-$(CONFIG_IOMMU_IO_PGTABLE_SHORT) += io-pgtable-arm-short.o
> > obj-$(CONFIG_IOMMU_IOVA) += iova.o
> > obj-$(CONFIG_OF_IOMMU) += of_iommu.o
> > obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o msm_iommu_dev.o
> > diff --git a/drivers/iommu/io-pgtable-arm-short.c b/drivers/iommu/io-pgtable-arm-short.c
> > new file mode 100644
> > index 0000000..cc286ce5
> > --- /dev/null
> > +++ b/drivers/iommu/io-pgtable-arm-short.c
> > @@ -0,0 +1,490 @@
> > +/*
> > + * Copyright (c) 2014-2015 MediaTek Inc.
> > + * Author: Yong Wu <yong.wu@xxxxxxxxxxxx>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + */
> > +#define pr_fmt(fmt) "arm-short-desc io-pgtable: "fmt
> > +
> > +#include <linux/err.h>
> > +#include <linux/mm.h>
> > +#include <linux/iommu.h>
> > +#include <linux/errno.h>
>
> Alphabetically-sorted includes, please. Also, this list doesn't look
> particularly correct - e.g. I don't think you're actually using anything
> from mm.h, but you are relying on stuff from kernel.h, slab.h, gfp.h,
> etc. being pulled in indirectly.
>
> > +
> > +#include "io-pgtable.h"
> > +
> > +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)
>
> This macro may as well be factored out into io-pgtable.h before
> duplication spreads any further. I don't see any reason for it not to
> live alongside the definition of struct io_pgtable, anyway.
Thanks. I will move it into io-pgtable.h.
Then I think this also should be deleted in io-pgtable-arm.c.
>
> > +
> > +#define io_pgtable_short_ops_to_data(x) \
> > + io_pgtable_short_to_data(io_pgtable_ops_to_pgtable(x))
> > +
> > +#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
> > +
> > +/* 1 level pagetable */
> > +#define ARM_SHORT_F_PGD_TYPE_PAGE (0x1)
> > +#define ARM_SHORT_F_PGD_TYPE_PAGE_MSK (0x3)
> > +#define ARM_SHORT_F_PGD_TYPE_SECTION (0x2)
> > +#define ARM_SHORT_F_PGD_TYPE_SUPERSECTION (0x2 | (1 << 18))
> > +#define ARM_SHORT_F_PGD_TYPE_SECTION_MSK (0x3 | (1 << 18))
> > +#define ARM_SHORT_F_PGD_TYPE_IS_PAGE(pgd) (((pgd) & 0x3) == 1)
>
> This confused me on first glance looking at the places it's used,
> because it's not actually referring to a thing which is a page. Maybe
> ..._IS_TABLE would be a better name?
Yes. It is better. From the spec, it is "page table".
Then How about "ARM_SHORT_F_PGD_TYPE_IS_PAGETABLE"?
It is a little long, but there are only 2 lines use it and Both are not
over 80 character even though "_IS_PAGETABLE".
>
> > +#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
> > +
> > +/* 2 level pagetable */
> > +#define ARM_SHORT_F_PTE_TYPE_GET(val) ((val) & 0x3)
> > +#define ARM_SHORT_F_PTE_TYPE_LARGE BIT(0)
> > +#define ARM_SHORT_F_PTE_TYPE_SMALL BIT(1)
> > +#define ARM_SHORT_F_PTE_B_BIT BIT(2)
> > +#define ARM_SHORT_F_PTE_C_BIT BIT(3)
> > +#define ARM_SHORT_F_PTE_IMPLE_BIT BIT(9)
> > +#define ARM_SHORT_F_PTE_S_BIT BIT(10)
> > +#define ARM_SHORT_F_PTE_PA_LARGE_MSK 0xffff0000
> > +#define ARM_SHORT_F_PTE_PA_SMALL_MSK 0xfffff000
> > +
> > +#define ARM_SHORT_PGD_IDX(a) ((a) >> ARM_SHORT_PGDIR_SHIFT)
> > +#define ARM_SHORT_PTE_IDX(a) \
> > + (((a) >> ARM_SHORT_PAGE_SHIFT) & 0xff)
> > +#define ARM_SHORT_GET_PTE_VA(pgd) \
> > + (phys_to_virt((unsigned long)pgd & ARM_SHORT_F_PGD_PA_PAGETABLE_MSK))
> > +
> > +static arm_short_iopte *
> > +arm_short_get_pte_in_pgd(arm_short_iopte curpgd, unsigned int iova)
> > +{
> > + arm_short_iopte *pte;
> > +
> > + pte = ARM_SHORT_GET_PTE_VA(curpgd);
> > + pte += ARM_SHORT_PTE_IDX(iova);
> > + return pte;
> > +}
> > +
> > +static arm_short_iopte *
> > +arm_short_supersection_start(arm_short_iopte *pgd)
> > +{
> > + return (arm_short_iopte *)(round_down((unsigned long)pgd, (16 * 4)));
> > +}
> > +
> > +static int _arm_short_check_free_pte(struct arm_short_io_pgtable *data,
> > + arm_short_iopte *pgd)
>
> Given that this is only returning success/failure, it should probably be
> bool rather than int.
Thanks.
>
> > +{
> > + 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;
> > + }
> > +
> > + /* Free PTE */
> > + kmem_cache_free(data->ptekmem, pte);
> > + *pgd = 0;
> > +
> > + return 0;
> > +}
> > +
> > +static phys_addr_t arm_short_iova_to_phys(struct io_pgtable_ops *ops,
> > + unsigned long iova)
> > +{
> > + struct arm_short_io_pgtable *data = io_pgtable_short_ops_to_data(ops);
> > + arm_short_iopte *pte, *pgd = data->pgd;
> > + phys_addr_t pa = 0;
> > +
> > + pgd += ARM_SHORT_PGD_IDX(iova);
> > +
> > + if (ARM_SHORT_F_PGD_TYPE_IS_PAGE(*pgd)) {
> > + u8 pte_type;
> > +
> > + pte = arm_short_get_pte_in_pgd(*pgd, iova);
> > + pte_type = ARM_SHORT_F_PTE_TYPE_GET(*pte);
> > +
> > + if (pte_type == ARM_SHORT_F_PTE_TYPE_LARGE) {
> > + pa = (*pte) & ARM_SHORT_F_PTE_PA_LARGE_MSK;
> > + pa |= iova & (~ARM_SHORT_F_PTE_PA_LARGE_MSK);
> > + } else if (pte_type == ARM_SHORT_F_PTE_TYPE_SMALL) {
> > + pa = (*pte) & ARM_SHORT_F_PTE_PA_SMALL_MSK;
> > + pa |= iova & (~ARM_SHORT_F_PTE_PA_SMALL_MSK);
> > + }
> > + } else {
> > + if (ARM_SHORT_F_PGD_TYPE_IS_SECTION(*pgd)) {
> > + pa = (*pgd) & ARM_SHORT_F_PGD_PA_SECTION_MSK;
> > + pa |= iova & (~ARM_SHORT_F_PGD_PA_SECTION_MSK);
> > + } else if (ARM_SHORT_F_PGD_TYPE_IS_SUPERSECTION(*pgd)) {
> > + pa = (*pgd) & ARM_SHORT_F_PGD_PA_SUPERSECTION_MSK;
> > + pa |= iova & (~ARM_SHORT_F_PGD_PA_SUPERSECTION_MSK);
> > + }
> > + }
> > +
> > + return pa;
> > +}
> > +
> > +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;
>
> Since everything's at page granularity, working with IOVA PFNs rather
> than raw addresses might be more convenient, and also sidesteps the
> 32-bit overflow problem. On 64-bit platforms, we're wasting a whole 95
> bits of a long long here ;)
About IOVA PFNs, if add it, we have to include "iova.h". then it may add
a new relationship with other module. I am not sure it is ok.
in pg-iotable-arm.c, I also don't see it. so I don't prepare to add iova
pfn, is it ok?
iova here always is 32bit, and iova+size may over 32bit. so I use "long
long" here. "long long" always is 64bit in 32bit&64bit platform?
"long" may be error while 32bit platform.
I will add split and try to delete this in next version.
>
> > + 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),
>
> Shouldn't this be page size for the IOMMU, not the CPU? I'm a bit slow
> today, but this looks like it might go wrong when PAGE_SIZE > 4K.
Thanks. Then I will add a define like this:
#define IOMMU_PAGE_SIZE_4K SZ_4K
And I will put it into io-pgtable.h, the io-pgtable-arm.c may also need
it.
>
> > + (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);
> > +
> > + 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;
> > + } 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",
>
> Nit: typo in "supersection" here.
>
> > + __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));
>
> iova = ALIGN(iova + SZ_16M, SZ_16M);
>
> Except that being unaligned in the first place is an error condition, so
> it would make more sense to just have "iova += SZ_16M;" here, and put
> "iova = ALIGN(iova, SZ_16M) after the warning in the error path above.
>
> Since you don't handle splitting block mappings, and you also seem to be
> missing an equivalent warning for unaligned second-level large pages, it
> might be better to simply return an error if the requested size and
> alignment don't exactly match the type of entry found, rather than let
> the page tables get into an unexpectedly inconsistent state.
OK. I will add split and add the align checking of start_iova for each
case..
>
> > + } else {
> > + break;
> > + }
> > + } while (iova < end_plus_1 && iova);
> > +
> > + tlb->tlb_add_flush(iova_start, size, true, cookie);
> > +
> > + return 0;
> > +}
> > +
> > +static arm_short_iopte __arm_short_pte_port(unsigned int prot, bool large)
>
> I assume _port is a typo of _prot
>
> > +{
> > + 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;
> > +
> > + return pteprot;
> > +}
> > +
> > +static arm_short_iopte __arm_short_pgd_port(int prot, bool super)
>
> Ditto
>
> > +{
> > + 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");
>
> Nit: you may as well just have largepage ? "large" : "small" here and
> "...type=%s page..." in the format string.
>
> > + 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");
>
> The allocator should already print the details of a failure, so I don't
> think this adds much.
>
> > + 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;
> > + }
>
> Can this ever actually happen? Besides, if kmem_cache_alloc isn't
> honouring the alignment specified in kmem_cache_create, I think the
> kernel might have bigger problems anyway...
Thanks. I will delete it.
>
> > + ptenew = true;
> > + *pgd = virt_to_phys(pte_new_va) | pgdprot;
> > + kmemleak_ignore(pte_new_va);
> > + 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);
> > + return -EEXIST;
> > + }
> > + }
> > +
> > + pteprot = (arm_short_iopte)pa;
> > + pteprot |= __arm_short_pte_port(prot, largepage);
> > +
[snip]
> > +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;
> > +
> > + 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;
> > + }
>
> I think this might be nicer as a switch statement. You could perhaps
> move the add_flush beforehand (since it's unconditional here anyway) and
> get rid of ret altogether.
move the add_flush before map?
if we change the pagetable firstly, then add_flush. is it better?
>
> Alternatively, given that map_page and map_section are so similar, maybe
> it's worth sorting out the pgprot and pgd/pte pointer for the
> page/section distinction here, then just passing those to a single
> function which maps compound/non-compound leaf entries.
Ok. I will try to merge them in one function like _arm_short_map.
>
> > + 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;
> > +
> > + if (cfg->oas > ARM_SHORT_MAX_ADDR_BITS)
> > + return NULL;
> > +
> > + cfg->pgsize_bitmap &= SZ_4K | SZ_64K | SZ_1M | SZ_16M;
> > +
> > + 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);
>
> I think this needs __GFP_DMA too, to ensure the pgd lies below the 4GB
> boundary on arm64/LPAE systems with memory above that.
Thanks.
> > @@ -62,6 +63,11 @@ struct io_pgtable_cfg {
> > u64 vttbr;
> > u64 vtcr;
> > } arm_lpae_s2_cfg;
> > +
> > + struct {
> > + u64 ttbr[2];
> > + u64 tcr;
>
> The ARM ARM defines these all as 32-bit registers for the
> short-descriptor format, so I think u32 would be more appropriate -
> better to let the compiler truncate things and warn about it, than have
> the hardware do it silently at runtime ;)
I will change both of them to u32.
>
> > + } arm_short_cfg;
> > };
> > };
> >
> > --
> > 1.8.1.1.dirty
> >
>
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