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-rw-r--r--drivers/vfio/vfio_iommu_spapr_tce.c82
1 files changed, 63 insertions, 19 deletions
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 64300ccb05db..6e2e15fdb0df 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -29,6 +29,51 @@
static void tce_iommu_detach_group(void *iommu_data,
struct iommu_group *iommu_group);
+static long try_increment_locked_vm(long npages)
+{
+ long ret = 0, locked, lock_limit;
+
+ if (!current || !current->mm)
+ return -ESRCH; /* process exited */
+
+ if (!npages)
+ return 0;
+
+ 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))
+ ret = -ENOMEM;
+ else
+ current->mm->locked_vm += npages;
+
+ pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid,
+ npages << PAGE_SHIFT,
+ current->mm->locked_vm << PAGE_SHIFT,
+ rlimit(RLIMIT_MEMLOCK),
+ ret ? " - exceeded" : "");
+
+ up_write(&current->mm->mmap_sem);
+
+ return ret;
+}
+
+static void decrement_locked_vm(long npages)
+{
+ if (!current || !current->mm || !npages)
+ return; /* process exited */
+
+ down_write(&current->mm->mmap_sem);
+ if (WARN_ON_ONCE(npages > current->mm->locked_vm))
+ npages = current->mm->locked_vm;
+ current->mm->locked_vm -= npages;
+ pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid,
+ npages << PAGE_SHIFT,
+ current->mm->locked_vm << PAGE_SHIFT,
+ rlimit(RLIMIT_MEMLOCK));
+ up_write(&current->mm->mmap_sem);
+}
+
/*
* VFIO IOMMU fd for SPAPR_TCE IOMMU implementation
*
@@ -45,6 +90,7 @@ struct tce_container {
struct mutex lock;
struct iommu_table *tbl;
bool enabled;
+ unsigned long locked_pages;
};
static bool tce_page_is_contained(struct page *page, unsigned page_shift)
@@ -60,7 +106,7 @@ static bool tce_page_is_contained(struct page *page, unsigned page_shift)
static int tce_iommu_enable(struct tce_container *container)
{
int ret = 0;
- unsigned long locked, lock_limit, npages;
+ unsigned long locked;
struct iommu_table *tbl = container->tbl;
if (!container->tbl)
@@ -89,21 +135,22 @@ static int tce_iommu_enable(struct tce_container *container)
* Also we don't have a nice way to fail on H_PUT_TCE due to ulimits,
* that would effectively kill the guest at random points, much better
* enforcing the limit based on the max that the guest can map.
+ *
+ * Unfortunately at the moment it counts whole tables, no matter how
+ * much memory the guest has. I.e. for 4GB guest and 4 IOMMU groups
+ * each with 2GB DMA window, 8GB will be counted here. The reason for
+ * this is that we cannot tell here the amount of RAM used by the guest
+ * as this information is only available from KVM and VFIO is
+ * KVM agnostic.
*/
- down_write(&current->mm->mmap_sem);
- npages = (tbl->it_size << tbl->it_page_shift) >> 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 {
+ locked = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT;
+ ret = try_increment_locked_vm(locked);
+ if (ret)
+ return ret;
- current->mm->locked_vm += npages;
- container->enabled = true;
- }
- up_write(&current->mm->mmap_sem);
+ container->locked_pages = locked;
+
+ container->enabled = true;
return ret;
}
@@ -115,13 +162,10 @@ static void tce_iommu_disable(struct tce_container *container)
container->enabled = false;
- if (!container->tbl || !current->mm)
+ if (!current->mm)
return;
- down_write(&current->mm->mmap_sem);
- current->mm->locked_vm -= (container->tbl->it_size <<
- container->tbl->it_page_shift) >> PAGE_SHIFT;
- up_write(&current->mm->mmap_sem);
+ decrement_locked_vm(container->locked_pages);
}
static void *tce_iommu_open(unsigned long arg)