pseries: Use Book3S-HV TCE acceleration capabilities

The pseries machine of qemu implements the TCE mechanism used as a
virtual IOMMU for the PAPR defined virtual IO devices.  Because the
PAPR spec only defines a small DMA address space, the guest VIO
drivers need to update TCE mappings very frequently - the virtual
network device is particularly bad.  This means many slow exits to
qemu to emulate the H_PUT_TCE hypercall.

Sufficiently recent kernels allow this to be mitigated by implementing
H_PUT_TCE in the host kernel.  To make use of this, however, qemu
needs to initialize the necessary TCE tables, and map them into itself
so that the VIO device implementations can retrieve the mappings when
they access guest memory (which is treated as a virtual DMA
operation).

This patch adds the necessary calls to use the KVM TCE acceleration.
If the kernel does not support acceleration, or there is some other
error creating the accelerated TCE table, then it will still fall back
to full userspace TCE implementation.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 14 insertions, 0 deletions

diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index 82f32f449e..87d1bdd5fd 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -22,6 +22,8 @@ int kvmppc_set_interrupt(CPUState *env, int irq, int level);
 void kvmppc_set_papr(CPUState *env);
 int kvmppc_smt_threads(void);
 off_t kvmppc_alloc_rma(const char *name, MemoryRegion *sysmem);
+void *kvmppc_create_spapr_tce(uint32_t liobn, uint32_t window_size, int *pfd);
+int kvmppc_remove_spapr_tce(void *table, int pfd, uint32_t window_size);
 
 #else
 
@@ -59,6 +61,18 @@ static inline off_t kvmppc_alloc_rma(const char *name, MemoryRegion *sysmem)
     return 0;
 }
 
+static inline void *kvmppc_create_spapr_tce(uint32_t liobn,
+                                            uint32_t window_size, int *fd)
+{
+    return NULL;
+}
+
+static inline int kvmppc_remove_spapr_tce(void *table, int pfd,
+                                          uint32_t window_size)
+{
+    return -1;
+}
+
 #endif
 
 #ifndef CONFIG_KVM