[PATCH kernel] KVM: PPC: Do not warn when userspace asked for too big TCE table

[Alexey Kardashevskiy]

KVM manages emulated TCE tables for guest LIOBNs by a two level table
which maps up to 128TiB with 16MB IOMMU pages (enabled in QEMU by default)
and MAX_ORDER=11 (the kernel's default). Note that the last level of
the table is allocated when actual TCE is updated.

However these tables are created via ioctl() on kvmfd and the userspace
can trigger WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp) in mm/page_alloc.c
and flood dmesg.

This adds __GFP_NOWARN.

Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
---

We could probably switch to vmalloc() to allow even bigger
emulated tables which we do not really want the userspace
to create though.

---
 arch/powerpc/kvm/book3s_64_vio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index d6589c4fe889..40864373ef87 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -307,7 +307,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
 		return ret;
 
 	ret = -ENOMEM;
-	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL);
+	stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL | __GFP_NOWARN);
 	if (!stt)
 		goto fail_acct;
 
-- 
2.30.2