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iommu/vt-d: Cleanup after converting to dma-iommu ops
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Some cleanups after converting the driver to use dma-iommu ops.
- Remove nobounce option;
- Cleanup and simplify the path in domain mapping.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Logan Gunthorpe <logang@deltatee.com>
Link: https://lore.kernel.org/r/20201124082057.2614359-8-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>
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Lu Baolu authored and Will Deacon committed Nov 25, 2020
1 parent c588072 commit 58a8bb3
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Showing 2 changed files with 28 additions and 67 deletions.
5 changes: 0 additions & 5 deletions Documentation/admin-guide/kernel-parameters.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -1883,11 +1883,6 @@
Note that using this option lowers the security
provided by tboot because it makes the system
vulnerable to DMA attacks.
nobounce [Default off]
Disable bounce buffer for untrusted devices such as
the Thunderbolt devices. This will treat the untrusted
devices as the trusted ones, hence might expose security
risks of DMA attacks.

intel_idle.max_cstate= [KNL,HW,ACPI,X86]
0 disables intel_idle and fall back on acpi_idle.
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90 changes: 28 additions & 62 deletions drivers/iommu/intel/iommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -355,7 +355,6 @@ static int dmar_forcedac;
static int intel_iommu_strict;
static int intel_iommu_superpage = 1;
static int iommu_identity_mapping;
static int intel_no_bounce;
static int iommu_skip_te_disable;

#define IDENTMAP_GFX 2
Expand Down Expand Up @@ -457,9 +456,6 @@ static int __init intel_iommu_setup(char *str)
} else if (!strncmp(str, "tboot_noforce", 13)) {
pr_info("Intel-IOMMU: not forcing on after tboot. This could expose security risk for tboot\n");
intel_iommu_tboot_noforce = 1;
} else if (!strncmp(str, "nobounce", 8)) {
pr_info("Intel-IOMMU: No bounce buffer. This could expose security risks of DMA attacks\n");
intel_no_bounce = 1;
}

str += strcspn(str, ",");
Expand Down Expand Up @@ -2277,15 +2273,14 @@ static inline int hardware_largepage_caps(struct dmar_domain *domain,
return level;
}

static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
struct scatterlist *sg, unsigned long phys_pfn,
unsigned long nr_pages, int prot)
static int
__domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
unsigned long phys_pfn, unsigned long nr_pages, int prot)
{
struct dma_pte *first_pte = NULL, *pte = NULL;
phys_addr_t pteval;
unsigned long sg_res = 0;
unsigned int largepage_lvl = 0;
unsigned long lvl_pages = 0;
phys_addr_t pteval;
u64 attr;

BUG_ON(!domain_pfn_supported(domain, iov_pfn + nr_pages - 1));
Expand All @@ -2297,26 +2292,14 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
if (domain_use_first_level(domain))
attr |= DMA_FL_PTE_PRESENT | DMA_FL_PTE_XD | DMA_FL_PTE_US;

if (!sg) {
sg_res = nr_pages;
pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | attr;
}
pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | attr;

while (nr_pages > 0) {
uint64_t tmp;

if (!sg_res) {
unsigned int pgoff = sg->offset & ~PAGE_MASK;

sg_res = aligned_nrpages(sg->offset, sg->length);
sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + pgoff;
sg->dma_length = sg->length;
pteval = (sg_phys(sg) - pgoff) | attr;
phys_pfn = pteval >> VTD_PAGE_SHIFT;
}

if (!pte) {
largepage_lvl = hardware_largepage_caps(domain, iov_pfn, phys_pfn, sg_res);
largepage_lvl = hardware_largepage_caps(domain, iov_pfn,
phys_pfn, nr_pages);

first_pte = pte = pfn_to_dma_pte(domain, iov_pfn, &largepage_lvl);
if (!pte)
Expand All @@ -2328,7 +2311,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
pteval |= DMA_PTE_LARGE_PAGE;
lvl_pages = lvl_to_nr_pages(largepage_lvl);

nr_superpages = sg_res / lvl_pages;
nr_superpages = nr_pages / lvl_pages;
end_pfn = iov_pfn + nr_superpages * lvl_pages - 1;

/*
Expand Down Expand Up @@ -2362,48 +2345,45 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
lvl_pages = lvl_to_nr_pages(largepage_lvl);

BUG_ON(nr_pages < lvl_pages);
BUG_ON(sg_res < lvl_pages);

nr_pages -= lvl_pages;
iov_pfn += lvl_pages;
phys_pfn += lvl_pages;
pteval += lvl_pages * VTD_PAGE_SIZE;
sg_res -= lvl_pages;

/* If the next PTE would be the first in a new page, then we
need to flush the cache on the entries we've just written.
And then we'll need to recalculate 'pte', so clear it and
let it get set again in the if (!pte) block above.
If we're done (!nr_pages) we need to flush the cache too.
Also if we've been setting superpages, we may need to
recalculate 'pte' and switch back to smaller pages for the
end of the mapping, if the trailing size is not enough to
use another superpage (i.e. sg_res < lvl_pages). */
* need to flush the cache on the entries we've just written.
* And then we'll need to recalculate 'pte', so clear it and
* let it get set again in the if (!pte) block above.
*
* If we're done (!nr_pages) we need to flush the cache too.
*
* Also if we've been setting superpages, we may need to
* recalculate 'pte' and switch back to smaller pages for the
* end of the mapping, if the trailing size is not enough to
* use another superpage (i.e. nr_pages < lvl_pages).
*/
pte++;
if (!nr_pages || first_pte_in_page(pte) ||
(largepage_lvl > 1 && sg_res < lvl_pages)) {
(largepage_lvl > 1 && nr_pages < lvl_pages)) {
domain_flush_cache(domain, first_pte,
(void *)pte - (void *)first_pte);
pte = NULL;
}

if (!sg_res && nr_pages)
sg = sg_next(sg);
}

return 0;
}

static int domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
struct scatterlist *sg, unsigned long phys_pfn,
unsigned long nr_pages, int prot)
static int
domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
unsigned long phys_pfn, unsigned long nr_pages, int prot)
{
int iommu_id, ret;
struct intel_iommu *iommu;

/* Do the real mapping first */
ret = __domain_mapping(domain, iov_pfn, sg, phys_pfn, nr_pages, prot);
ret = __domain_mapping(domain, iov_pfn, phys_pfn, nr_pages, prot);
if (ret)
return ret;

Expand All @@ -2415,20 +2395,6 @@ static int domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
return 0;
}

static inline int domain_sg_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
struct scatterlist *sg, unsigned long nr_pages,
int prot)
{
return domain_mapping(domain, iov_pfn, sg, 0, nr_pages, prot);
}

static inline int domain_pfn_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
unsigned long phys_pfn, unsigned long nr_pages,
int prot)
{
return domain_mapping(domain, iov_pfn, NULL, phys_pfn, nr_pages, prot);
}

static void domain_context_clear_one(struct intel_iommu *iommu, u8 bus, u8 devfn)
{
unsigned long flags;
Expand Down Expand Up @@ -2688,7 +2654,7 @@ static int iommu_domain_identity_map(struct dmar_domain *domain,
*/
dma_pte_clear_range(domain, first_vpfn, last_vpfn);

return __domain_mapping(domain, first_vpfn, NULL,
return __domain_mapping(domain, first_vpfn,
first_vpfn, last_vpfn - first_vpfn + 1,
DMA_PTE_READ|DMA_PTE_WRITE);
}
Expand Down Expand Up @@ -4942,8 +4908,8 @@ static int intel_iommu_map(struct iommu_domain *domain,
/* Round up size to next multiple of PAGE_SIZE, if it and
the low bits of hpa would take us onto the next page */
size = aligned_nrpages(hpa, size);
ret = domain_pfn_mapping(dmar_domain, iova >> VTD_PAGE_SHIFT,
hpa >> VTD_PAGE_SHIFT, size, prot);
ret = domain_mapping(dmar_domain, iova >> VTD_PAGE_SHIFT,
hpa >> VTD_PAGE_SHIFT, size, prot);
return ret;
}

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