[PATCH v3 04/18] vfio: powerpc: Move locked_vm accounting to a helper

[Alexey Kardashevskiy]

Additional DMA windows support is coming and accounting will include them
so let's move this code to a helper for reuse.

Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
 drivers/vfio/vfio_iommu_spapr_tce.c | 54 ++++++++++++++++++++++++-------------
 1 file changed, 36 insertions(+), 18 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c 
b/drivers/vfio/vfio_iommu_spapr_tce.c
index a84788b..c8f7284 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -47,10 +47,40 @@ struct tce_container {
        bool enabled;
 };
 
+/*
+ * Checks ulimit in order not to let the user space to pin all
+ * available memory for TCE tables.
+ */
+static long tce_iommu_account_memlimit(struct iommu_table *tbl, bool inc)
+{
+       unsigned long ret = 0, locked, lock_limit;
+       long npages;
+
+       if (!current->mm)
+               return -ESRCH; /* process exited */
+
+       npages = (tbl->it_size << IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
+       if (!inc)
+               npages = -npages;
+
+       down_write(&current->mm->mmap_sem);
+       locked = current->mm->locked_vm + npages;
+       lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+       if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
+               pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n",
+                               rlimit(RLIMIT_MEMLOCK));
+               ret = -ENOMEM;
+       } else {
+               current->mm->locked_vm += npages;
+       }
+       up_write(&current->mm->mmap_sem);
+
+       return ret;
+}
+
 static int tce_iommu_enable(struct tce_container *container)
 {
        int ret = 0;
-       unsigned long locked, lock_limit, npages;
        struct iommu_table *tbl = container->tbl;
 
        if (!container->tbl)
@@ -80,20 +110,11 @@ static int tce_iommu_enable(struct tce_container 
*container)
         * that would effectively kill the guest at random points, much better
         * enforcing the limit based on the max that the guest can map.
         */
-       down_write(&current->mm->mmap_sem);
-       npages = (tbl->it_size << IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
-       locked = current->mm->locked_vm + npages;
-       lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-       if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
-               pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n",
-                               rlimit(RLIMIT_MEMLOCK));
-               ret = -ENOMEM;
-       } else {
+       ret = tce_iommu_account_memlimit(tbl, true);
+       if (ret)
+               return ret;
 
-               current->mm->locked_vm += npages;
-               container->enabled = true;
-       }
-       up_write(&current->mm->mmap_sem);
+       container->enabled = true;
 
        return ret;
 }
@@ -108,10 +129,7 @@ static void tce_iommu_disable(struct tce_container 
*container)
        if (!container->tbl || !current->mm)
                return;
 
-       down_write(&current->mm->mmap_sem);
-       current->mm->locked_vm -= (container->tbl->it_size <<
-                       IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
-       up_write(&current->mm->mmap_sem);
+       tce_iommu_account_memlimit(container->tbl, false);
 }
 
 static void *tce_iommu_open(unsigned long arg)
-- 
2.0.0

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