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iommu: bcm2712-iommu: Map and unmap multiple pages in a single call
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For efficiency, the map_pages() and unmap_pages() calls now pay
attention to their "count" argument.

Remove a special case for a "pass-through" address range, which
the DMA/IOMMU subsystem isn't told exists and should never use.

Fix a bug where we omitted to set *mapped to 0 in error cases.
Minor style fixes and tidying.

Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>
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@njhollinghurst @popcornmix
njhollinghurst authored and popcornmix committed Feb 23, 2024
1 parent 7ed82d9 commit de86df7
Showing 1 changed file with 67 additions and 58 deletions.
125 changes: 67 additions & 58 deletions drivers/iommu/bcm2712-iommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -241,42 +241,48 @@ static int bcm2712_iommu_map(struct iommu_domain *domain, unsigned long iova,
int prot, gfp_t gfp, size_t *mapped)
{
struct bcm2712_iommu *mmu = domain_to_mmu(domain);

(void)gfp;
iova -= mmu->dma_iova_offset;
if (iova >= APERTURE_BASE && iova + bytes <= APERTURE_TOP) {
unsigned int p;
u32 entry = MMMU_PTE_VALID | (pa >> MMU_PAGE_SHIFT);
u32 align = (u32)(iova | pa | bytes);

/* large page and write enable flags */
if (!(align & ((1 << HUGEPAGE_SHIFT) - 1)))
entry |= FIELD_PREP(MMMU_PTE_PAGESIZE_MASK, 3);
else if (!(align & mmu->superpage_mask) && mmu->superpage_mask)
entry |= FIELD_PREP(MMMU_PTE_PAGESIZE_MASK, 2);
else if (!(align & mmu->bigpage_mask) && mmu->bigpage_mask)
entry |= FIELD_PREP(MMMU_PTE_PAGESIZE_MASK, 1);
if (prot & IOMMU_WRITE)
entry |= MMMU_PTE_WRITEABLE;

/* Ensure tables are cache-coherent with CPU */
if (!mmu->dirty) {
dma_sync_sgtable_for_cpu(mmu->dev, mmu->sgt, DMA_TO_DEVICE);
mmu->dirty = true;
}

iova -= APERTURE_BASE;
for (p = iova >> MMU_PAGE_SHIFT;
p < (iova + bytes) >> MMU_PAGE_SHIFT; p++) {
mmu->nmapped_pages += !(mmu->tables[p]);
mmu->tables[p] = entry++;
}
} else if (iova + bytes > APERTURE_BASE || iova != pa) {
dev_warn(mmu->dev, "%s: iova=0x%lx pa=0x%llx size=0x%llx OUT OF RANGE!\n",
u32 entry = MMMU_PTE_VALID | (pa >> MMU_PAGE_SHIFT);
u32 align = (u32)(iova | pa | bytes);
unsigned int p;

/* Reject if at least the first page is not within our aperture */
if (iova < mmu->dma_iova_offset + APERTURE_BASE ||
iova + bytes > mmu->dma_iova_offset + APERTURE_TOP) {
dev_warn(mmu->dev, "%s: iova=0x%lx pa=0x%llx bytes=0x%lx OUT OF RANGE\n",
__func__, iova,
(unsigned long long)pa, (unsigned long long)bytes);
(unsigned long long)pa, (unsigned long)bytes);
*mapped = 0;

return -EINVAL;
}

/* large page and write enable flags */
if (!(align & ((1 << HUGEPAGE_SHIFT) - 1)))
entry |= FIELD_PREP(MMMU_PTE_PAGESIZE_MASK, 3);
else if (!(align & mmu->superpage_mask) && mmu->superpage_mask)
entry |= FIELD_PREP(MMMU_PTE_PAGESIZE_MASK, 2);
else if (!(align & mmu->bigpage_mask) && mmu->bigpage_mask)
entry |= FIELD_PREP(MMMU_PTE_PAGESIZE_MASK, 1);
if (prot & IOMMU_WRITE)
entry |= MMMU_PTE_WRITEABLE;

/* Ensure tables are cache-coherent with CPU */
if (!mmu->dirty) {
dma_sync_sgtable_for_cpu(mmu->dev, mmu->sgt, DMA_TO_DEVICE);
mmu->dirty = true;
}

/* Make iova relative to table base; amalgamate count pages */
iova -= (mmu->dma_iova_offset + APERTURE_BASE);
bytes = min(APERTURE_SIZE - iova, count * bytes);

/* Iterate over table by smallest native IOMMU page size */
for (p = iova >> MMU_PAGE_SHIFT;
p < (iova + bytes) >> MMU_PAGE_SHIFT; p++) {
mmu->nmapped_pages += !(mmu->tables[p]);
mmu->tables[p] = entry++;
}

*mapped = bytes;

return 0;
Expand All @@ -287,42 +293,45 @@ static size_t bcm2712_iommu_unmap(struct iommu_domain *domain, unsigned long iov
struct iommu_iotlb_gather *gather)
{
struct bcm2712_iommu *mmu = domain_to_mmu(domain);
unsigned int p;

if (iova >= mmu->dma_iova_offset + APERTURE_BASE &&
iova + bytes <= mmu->dma_iova_offset + APERTURE_TOP) {
unsigned int p;
if (iova < mmu->dma_iova_offset + APERTURE_BASE ||
iova + bytes > mmu->dma_iova_offset + APERTURE_TOP)
return 0;

/* Record just the lower and upper bounds in "gather" */
if (gather) {
bool empty = (gather->end <= gather->start);
/* Record just the lower and upper bounds in "gather" */
if (gather) {
bool empty = (gather->end <= gather->start);

if (empty || gather->start < iova)
gather->start = iova;
if (empty || gather->end < iova + bytes)
gather->end = iova + bytes;
}
if (empty || gather->start < iova)
gather->start = iova;
if (empty || gather->end < iova + bytes)
gather->end = iova + bytes;
}

/* Ensure tables are cache-coherent with CPU */
if (!mmu->dirty) {
dma_sync_sgtable_for_cpu(mmu->dev, mmu->sgt, DMA_TO_DEVICE);
mmu->dirty = true;
}
/* Ensure tables are cache-coherent with CPU */
if (!mmu->dirty) {
dma_sync_sgtable_for_cpu(mmu->dev, mmu->sgt, DMA_TO_DEVICE);
mmu->dirty = true;
}

/* Clear table entries, this marks the addresses as illegal */
iova -= (mmu->dma_iova_offset + APERTURE_BASE);
for (p = iova >> MMU_PAGE_SHIFT;
p < (iova + bytes) >> MMU_PAGE_SHIFT;
p++) {
mmu->nmapped_pages -= !!(mmu->tables[p]);
mmu->tables[p] = 0;
}
/* Make iova relative to table base; amalgamate count pages */
iova -= (mmu->dma_iova_offset + APERTURE_BASE);
bytes = min(APERTURE_SIZE - iova, count * bytes);

/* Clear table entries, this marks the addresses as illegal */
for (p = iova >> MMU_PAGE_SHIFT;
p < (iova + bytes) >> MMU_PAGE_SHIFT;
p++) {
mmu->nmapped_pages -= !!(mmu->tables[p]);
mmu->tables[p] = 0;
}

return bytes;
}

static int bcm2712_iommu_sync_range(struct iommu_domain *domain,
unsigned long iova, size_t size)
unsigned long iova, size_t size)
{
struct bcm2712_iommu *mmu = domain_to_mmu(domain);
unsigned long iova_end;
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