[Qemu-devel] [PATCH] powerpc iommu: enable multiple TCE requests

[Alexey Kardashevskiy]

Currently only single TCE entry per requiest is supported (H_PUT_TCE).
However PAPR+ specification allows multiple entry requests such as
H_PUT_TCE_INDIRECT and H_STUFFF_TCE. Having less transitions to the host
kernel via ioctls, support of these calls can accelerate IOMMU operations.

This also removes some leftovers in debug output of the H_PUT_TCE handler.

Signed-off-by: Alexey Kardashevskiy <address@hidden>
Signed-off-by: David Gibson <address@hidden>
---

This patch requires a KVM_CAP_SPAPR_MULTITCE capability from kernel headers
which is not there yet.
However it still would be nice to have "Reviewed-by" from someone when
the capability will make it to the upstream. Thanks.

---
 hw/ppc/spapr.c       | 16 ++++++++++--
 hw/ppc/spapr_iommu.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++---
 target-ppc/kvm.c     |  7 +++++
 target-ppc/kvm_ppc.h |  7 +++++
 4 files changed, 99 insertions(+), 5 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 9494915..a6b1f54 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -301,6 +301,8 @@ static void *spapr_create_fdt_skel(const char *cpu_model,
     CPUState *cs;
     uint32_t start_prop = cpu_to_be32(initrd_base);
     uint32_t end_prop = cpu_to_be32(initrd_base + initrd_size);
+    char hypertas_propm[] = 
"hcall-pft\0hcall-term\0hcall-dabr\0hcall-interrupt"
+        "\0hcall-tce\0hcall-vio\0hcall-splpar\0hcall-bulk\0hcall-multi-tce";
     char hypertas_prop[] = "hcall-pft\0hcall-term\0hcall-dabr\0hcall-interrupt"
         "\0hcall-tce\0hcall-vio\0hcall-splpar\0hcall-bulk";
     char qemu_hypertas_prop[] = "hcall-memop1";
@@ -480,8 +482,18 @@ static void *spapr_create_fdt_skel(const char *cpu_model,
     /* RTAS */
     _FDT((fdt_begin_node(fdt, "rtas")));
 
-    _FDT((fdt_property(fdt, "ibm,hypertas-functions", hypertas_prop,
-                       sizeof(hypertas_prop))));
+    /* In TCG mode, the multitce functions, which we implement are a
+     * win.  With KVM, we could fall back to the qemu implementation
+     * when KVM doesn't support them, but that would be much slower
+     * than just using the KVM implementations of the single TCE
+     * hypercalls. */
+    if (kvmppc_spapr_use_multitce()) {
+        _FDT((fdt_property(fdt, "ibm,hypertas-functions", hypertas_propm,
+                           sizeof(hypertas_propm))));
+    } else {
+        _FDT((fdt_property(fdt, "ibm,hypertas-functions", hypertas_prop,
+                           sizeof(hypertas_prop))));
+    }
     _FDT((fdt_property(fdt, "qemu,hypertas-functions", qemu_hypertas_prop,
                        sizeof(qemu_hypertas_prop))));
 
diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
index 3d4a1fc..22b09be 100644
--- a/hw/ppc/spapr_iommu.c
+++ b/hw/ppc/spapr_iommu.c
@@ -244,6 +244,71 @@ static target_ulong put_tce_emu(sPAPRTCETable *tcet, 
target_ulong ioba,
     return H_SUCCESS;
 }
 
+static target_ulong h_put_tce_indirect(PowerPCCPU *cpu,
+                                       sPAPREnvironment *spapr,
+                                       target_ulong opcode, target_ulong *args)
+{
+    int i;
+    target_ulong liobn = args[0];
+    target_ulong ioba = args[1];
+    target_ulong tce_list = args[2];
+    target_ulong npages = args[3];
+    target_ulong ret = 0;
+    sPAPRTCETable *tcet = spapr_tce_find_by_liobn(liobn);
+
+    if (tcet) {
+        for (i = 0; i < npages; ++i, ioba += SPAPR_TCE_PAGE_SIZE) {
+            target_ulong tce = ldq_phys((tce_list & ~SPAPR_TCE_PAGE_MASK) +
+                                        i * sizeof(target_ulong));
+            ret = put_tce_emu(tcet, ioba, tce);
+            if (ret) {
+                break;
+            }
+        }
+        return ret;
+    }
+#ifdef DEBUG_TCE
+    fprintf(stderr, "%s on liobn=" TARGET_FMT_lx
+            "  ioba 0x" TARGET_FMT_lx "  TCE 0x" TARGET_FMT_lx
+            " ret = " TARGET_FMT_ld "\n",
+            __func__, liobn, ioba, tce_list, ret);
+#endif
+
+    return H_PARAMETER;
+}
+
+static target_ulong h_stuff_tce(PowerPCCPU *cpu, sPAPREnvironment *spapr,
+                              target_ulong opcode, target_ulong *args)
+{
+    int i;
+    target_ulong liobn = args[0];
+    target_ulong ioba = args[1];
+    target_ulong tce_value = args[2];
+    target_ulong npages = args[3];
+    target_ulong ret = 0;
+    sPAPRTCETable *tcet = spapr_tce_find_by_liobn(liobn);
+
+    ioba &= ~(SPAPR_TCE_PAGE_SIZE - 1);
+
+    if (tcet) {
+        for (i = 0; i < npages; ++i, ioba += SPAPR_TCE_PAGE_SIZE) {
+            ret = put_tce_emu(tcet, ioba, tce_value);
+            if (ret) {
+                break;
+            }
+        }
+        return ret;
+    }
+#ifdef DEBUG_TCE
+    fprintf(stderr, "%s on liobn=" TARGET_FMT_lx
+            "  ioba 0x" TARGET_FMT_lx "  TCE 0x" TARGET_FMT_lx
+            " ret = " TARGET_FMT_ld "\n",
+            __func__, liobn, ioba, tce_value, ret);
+#endif
+
+    return H_PARAMETER;
+}
+
 static target_ulong h_put_tce(PowerPCCPU *cpu, sPAPREnvironment *spapr,
                               target_ulong opcode, target_ulong *args)
 {
@@ -258,9 +323,10 @@ static target_ulong h_put_tce(PowerPCCPU *cpu, 
sPAPREnvironment *spapr,
         return put_tce_emu(tcet, ioba, tce);
     }
 #ifdef DEBUG_TCE
-    fprintf(stderr, "%s on liobn=" TARGET_FMT_lx /*%s*/
-            "  ioba 0x" TARGET_FMT_lx "  TCE 0x" TARGET_FMT_lx "\n",
-            __func__, liobn, /*dev->qdev.id, */ioba, tce);
+    fprintf(stderr, "%s on liobn=" TARGET_FMT_lx
+            "  ioba 0x" TARGET_FMT_lx "  TCE 0x" TARGET_FMT_lx
+            " ret = " TARGET_FMT_ld "\n",
+            __func__, liobn, ioba, tce, ret);
 #endif
 
     return H_PARAMETER;
@@ -318,6 +384,8 @@ static void spapr_tce_table_class_init(ObjectClass *klass, 
void *data)
 
     /* hcall-tce */
     spapr_register_hypercall(H_PUT_TCE, h_put_tce);
+    spapr_register_hypercall(H_PUT_TCE_INDIRECT, h_put_tce_indirect);
+    spapr_register_hypercall(H_STUFF_TCE, h_stuff_tce);
 }
 
 static TypeInfo spapr_tce_table_info = {
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 8afa7eb..97ac670 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -60,6 +60,7 @@ static int cap_booke_sregs;
 static int cap_ppc_smt;
 static int cap_ppc_rma;
 static int cap_spapr_tce;
+static int cap_spapr_multitce;
 static int cap_hior;
 static int cap_one_reg;
 static int cap_epr;
@@ -96,6 +97,7 @@ int kvm_arch_init(KVMState *s)
     cap_ppc_smt = kvm_check_extension(s, KVM_CAP_PPC_SMT);
     cap_ppc_rma = kvm_check_extension(s, KVM_CAP_PPC_RMA);
     cap_spapr_tce = kvm_check_extension(s, KVM_CAP_SPAPR_TCE);
+    cap_spapr_multitce = kvm_check_extension(s, KVM_CAP_SPAPR_MULTITCE);
     cap_one_reg = kvm_check_extension(s, KVM_CAP_ONE_REG);
     cap_hior = kvm_check_extension(s, KVM_CAP_PPC_HIOR);
     cap_epr = kvm_check_extension(s, KVM_CAP_PPC_EPR);
@@ -1603,6 +1605,11 @@ uint64_t kvmppc_rma_size(uint64_t current_size, unsigned 
int hash_shift)
 }
 #endif
 
+bool kvmppc_spapr_use_multitce(void)
+{
+    return !kvm_enabled() || cap_spapr_multitce;
+}
+
 void *kvmppc_create_spapr_tce(uint32_t liobn, uint32_t window_size, int *pfd)
 {
     struct kvm_create_spapr_tce args = {
diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index 12564ef..a2a903f 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -31,6 +31,7 @@ int kvmppc_set_tcr(PowerPCCPU *cpu);
 int kvmppc_booke_watchdog_enable(PowerPCCPU *cpu);
 #ifndef CONFIG_USER_ONLY
 off_t kvmppc_alloc_rma(const char *name, MemoryRegion *sysmem);
+bool kvmppc_spapr_use_multitce(void);
 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);
 int kvmppc_reset_htab(int shift_hint);
@@ -125,6 +126,12 @@ static inline off_t kvmppc_alloc_rma(const char *name, 
MemoryRegion *sysmem)
     return 0;
 }
 
+static inline bool kvmppc_spapr_use_multitce(void)
+{
+    /* No KVM, so always use the qemu multitce implementations */
+    return true;
+}
+
 static inline void *kvmppc_create_spapr_tce(uint32_t liobn,
                                             uint32_t window_size, int *fd)
 {
-- 
1.8.3.2