The new H-Call H_GET_CPU_CHARACTERISTICS is used by the guest to query
behaviours and available characteristics of the cpu.
Implement the handler for this new H-Call which formulates its response
based on the setting of the new capabilities added in the previous
patch.
Note: Currently we return H_FUNCTION under TCG which will direct the
guest to fall back to doing a displacement flush
Discussion:
Is TCG affected?
Is there any point in telling the guest to do these workarounds on TCG
given they're unlikely to translate to host instructions which have the
desired effect?
---
hw/ppc/spapr_hcall.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/hw/ppc/spapr.h | 1 +
2 files changed, 82 insertions(+)
diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 51eba52e86..b62b47c8d9 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1654,6 +1654,84 @@ static target_ulong
h_client_architecture_support(PowerPCCPU *cpu,
return H_SUCCESS;
}
+#define CPU_CHARACTERISTIC_SPEC_BARRIER (1ULL << (63 - 0))
+#define CPU_CHARACTERISTIC_BCCTR_SERIAL (1ULL << (63 - 1))
+#define CPU_CHARACTERISTIC_ORI_L1_CACHE (1ULL << (63 - 2))
+#define CPU_CHARACTERISTIC_MTTRIG_L1_CACHE (1ULL << (63 - 3))
+#define CPU_CHARACTERISTIC_L1_CACHE_PRIV (1ULL << (63 - 4))
+#define CPU_CHARACTERISTIC_BRANCH_HINTS (1ULL << (63 - 5))
+#define CPU_CHARACTERISTIC_MTTRIG_THR_RECONF (1ULL << (63 - 6))
+#define CPU_BEHAVIOUR_FAVOUR_SECURITY (1ULL << (63 - 0))
+#define CPU_BEHAVIOUR_L1_CACHE_FLUSH (1ULL << (63 - 1))
+#define CPU_BEHAVIOUR_SPEC_BARRIER (1ULL << (63 - 2))
+
+static target_ulong h_get_cpu_characteristics(PowerPCCPU *cpu,
+ sPAPRMachineState *spapr,
+ target_ulong opcode,
+ target_ulong *args)
+{
+ uint64_t characteristics = CPU_CHARACTERISTIC_BRANCH_HINTS;
+ uint64_t behaviour = CPU_BEHAVIOUR_FAVOUR_SECURITY;
+ uint8_t safe_cache = spapr_get_cap(spapr, SPAPR_CAP_CFPC);
+ uint8_t safe_bounds_check = spapr_get_cap(spapr, SPAPR_CAP_SBBC);
+ uint8_t safe_indirect_branch = spapr_get_cap(spapr, SPAPR_CAP_IBS);
+
+ /* TODO: Is TCG vulnerable? */
+ if (!kvm_enabled()) {
+ return H_FUNCTION;
+ }
+
+ switch (safe_cache) {
+ case SPAPR_CAP_WORKAROUND:
+ characteristics |= CPU_CHARACTERISTIC_ORI_L1_CACHE;
+ characteristics |= CPU_CHARACTERISTIC_MTTRIG_L1_CACHE;
+ characteristics |= CPU_CHARACTERISTIC_L1_CACHE_PRIV;
+ behaviour |= CPU_BEHAVIOUR_L1_CACHE_FLUSH;
+ break;
+ case SPAPR_CAP_FIXED:
+ break;
+ default: /* broken */
+ if (safe_cache != SPAPR_CAP_BROKEN) {
+ error_report("Invalid value for KVM_CAP_PPC_SAFE_CACHE (%d),
assuming broken",
+ safe_cache);
+ }
+ behaviour |= CPU_BEHAVIOUR_L1_CACHE_FLUSH;
+ break;
+ }
+
+ switch (safe_bounds_check) {
+ case SPAPR_CAP_WORKAROUND:
+ characteristics |= CPU_CHARACTERISTIC_SPEC_BARRIER;
+ behaviour |= CPU_BEHAVIOUR_SPEC_BARRIER;
+ break;
+ case SPAPR_CAP_FIXED:
+ break;
+ default: /* broken */
+ if (safe_bounds_check != SPAPR_CAP_BROKEN) {
+ error_report("Invalid value for KVM_CAP_PPC_SAFE_BOUNDS_CHECK
(%d), assuming broken",
+ safe_bounds_check);
+ }
+ behaviour |= CPU_BEHAVIOUR_SPEC_BARRIER;
+ break;
+ }
+
+ switch (safe_indirect_branch) {
+ case SPAPR_CAP_FIXED:
+ characteristics |= CPU_CHARACTERISTIC_BCCTR_SERIAL;
+ default: /* broken */
+ if (safe_indirect_branch != SPAPR_CAP_BROKEN) {
+ error_report("Invalid value for KVM_CAP_PPC_SAFE_INDIRECT_BRANCH
(%d), assuming broken",
+ safe_indirect_branch);
+ }
+ break;
+ }
+
+ args[0] = characteristics;
+ args[1] = behaviour;
+
+ return H_SUCCESS;
+}
+
static spapr_hcall_fn papr_hypercall_table[(MAX_HCALL_OPCODE / 4) + 1];
static spapr_hcall_fn kvmppc_hypercall_table[KVMPPC_HCALL_MAX -
KVMPPC_HCALL_BASE + 1];
@@ -1733,6 +1811,9 @@ static void hypercall_register_types(void)
spapr_register_hypercall(H_INVALIDATE_PID, h_invalidate_pid);
spapr_register_hypercall(H_REGISTER_PROC_TBL, h_register_process_table);
+ /* hcall-get-cpu-characteristics */
+ spapr_register_hypercall(H_GET_CPU_CHARACTERISTICS,
h_get_cpu_characteristics);
+
/* "debugger" hcalls (also used by SLOF). Note: We do -not- differenciate
* here between the "CI" and the "CACHE" variants, they will use whatever
* mapping attributes qemu is using. When using KVM, the kernel will
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 2db2f3e2e2..5677c38d2a 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -396,6 +396,7 @@ struct sPAPRMachineState {
#define H_GET_HCA_INFO 0x1B8
#define H_GET_PERF_COUNT 0x1BC
#define H_MANAGE_TRACE 0x1C0
+#define H_GET_CPU_CHARACTERISTICS 0x1C8
#define H_FREE_LOGICAL_LAN_BUFFER 0x1D4
#define H_QUERY_INT_STATE 0x1E4
#define H_POLL_PENDING 0x1D8
--
2.13.6
