Re: [PATCH kernel v6 3/7] vfio/spapr: Postpone allocation of userspace version of TCE table
From: David Gibson <hidden>
Date: 2016-11-29 04:44:08
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kvm
On Thu, Nov 24, 2016 at 04:48:06PM +1100, Alexey Kardashevskiy wrote:
The iommu_table struct manages a hardware TCE table and a vmalloc'd table with corresponding userspace addresses. Both are allocated when the default DMA window is created and this happens when the very first group is attached to a container. As we are going to allow the userspace to configure container in one memory context and pas container fd to another, we have to postpones such allocations till a container fd is passed to the destination user process so we would account locked memory limit against the actual container user constrainsts. This postpones the it_userspace array allocation till it is used first time for mapping. The unmapping patch already checks if the array is allocated. Signed-off-by: Alexey Kardashevskiy <redacted>
Reviewed-by: David Gibson <redacted>
quoted hunk ↗ jump to hunk
--- Changes: v6: * moved missing hunk from the next patch: tce_iommu_create_table() would decrement locked_vm while new caller - tce_iommu_build_v2() - will not; this adds a new return code to the DMA mapping path but this seems to be a minor change. --- drivers/vfio/vfio_iommu_spapr_tce.c | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-)diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c index d0c38b2..4efd2b2 100644 --- a/drivers/vfio/vfio_iommu_spapr_tce.c +++ b/drivers/vfio/vfio_iommu_spapr_tce.c@@ -515,6 +515,12 @@ static long tce_iommu_build_v2(struct tce_container *container, unsigned long hpa; enum dma_data_direction dirtmp; + if (!tbl->it_userspace) { + ret = tce_iommu_userspace_view_alloc(tbl); + if (ret) + return ret; + } + for (i = 0; i < pages; ++i) { struct mm_iommu_table_group_mem_t *mem = NULL; unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl,@@ -588,15 +594,6 @@ static long tce_iommu_create_table(struct tce_container *container, WARN_ON(!ret && !(*ptbl)->it_ops->free); WARN_ON(!ret && ((*ptbl)->it_allocated_size != table_size)); - if (!ret && container->v2) { - ret = tce_iommu_userspace_view_alloc(*ptbl); - if (ret) - (*ptbl)->it_ops->free(*ptbl); - } - - if (ret) - decrement_locked_vm(table_size >> PAGE_SHIFT); - return ret; }@@ -1068,10 +1065,7 @@ static int tce_iommu_take_ownership(struct tce_container *container, if (!tbl || !tbl->it_map) continue; - rc = tce_iommu_userspace_view_alloc(tbl); - if (!rc) - rc = iommu_take_ownership(tbl); - + rc = iommu_take_ownership(tbl); if (rc) { for (j = 0; j < i; ++j) iommu_release_ownership(
-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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