pseries: Enable in-kernel H_LOGICAL_CI_{LOAD, STORE} implementations

qemu currently implements the hypercalls H_LOGICAL_CI_LOAD and
H_LOGICAL_CI_STORE as PAPR extensions.  These are used by the SLOF firmware
for IO, because performing cache inhibited MMIO accesses with the MMU off
(real mode) is very awkward on POWER.

This approach breaks when SLOF needs to access IO devices implemented
within KVM instead of in qemu.  The simplest example would be virtio-blk
using an iothread, because the iothread / dataplane mechanism relies on
an in-kernel implementation of the virtio queue notification MMIO.

To fix this, an in-kernel implementation of these hypercalls has been made,
(kernel commit 99342cf "kvmppc: Implement H_LOGICAL_CI_{LOAD,STORE} in KVM"
however, the hypercalls still need to be enabled from qemu.  This performs
the necessary calls to do so.

It would be nice to provide some warning if we encounter a problematic
device with a kernel which doesn't support the new calls.  Unfortunately,
I can't see a way to detect this case which won't either warn in far too
many cases that will probably work, or which is horribly invasive.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 2e9ac87630eebee7881ac951a4bcff5691c4836e..f174e5a0f32413d296b3014afc1d45d5880746a8 100644 (file)
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1506,6 +1506,11 @@ static void ppc_spapr_init(MachineState *machine)
         qemu_register_reset(spapr_cpu_reset, cpu);
     }
 
+    if (kvm_enabled()) {
+        /* Enable H_LOGICAL_CI_* so SLOF can talk to in-kernel devices */
+        kvmppc_enable_logical_ci_hcalls();
+    }
+
     /* allocate RAM */
     spapr->ram_limit = ram_size;
     memory_region_allocate_system_memory(ram, NULL, "ppc_spapr.ram",

diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 1da9ea81e5415e940c6cbed25a7300e133309d2c..97a50b1de399e933c6d25c1f06169358fbc1b058 100644 (file)
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -1884,6 +1884,23 @@ int kvmppc_get_hypercall(CPUPPCState *env, uint8_t *buf, int buf_len)
     return 0;
 }
 
+static inline int kvmppc_enable_hcall(KVMState *s, target_ulong hcall)
+{
+    return kvm_vm_enable_cap(s, KVM_CAP_PPC_ENABLE_HCALL, 0, hcall, 1);
+}
+
+void kvmppc_enable_logical_ci_hcalls(void)
+{
+    /*
+     * FIXME: it would be nice if we could detect the cases where
+     * we're using a device which requires the in kernel
+     * implementation of these hcalls, but the kernel lacks them and
+     * produce a warning.
+     */
+    kvmppc_enable_hcall(kvm_state, H_LOGICAL_CI_LOAD);
+    kvmppc_enable_hcall(kvm_state, H_LOGICAL_CI_STORE);
+}
+
 void kvmppc_set_papr(PowerPCCPU *cpu)
 {
     CPUState *cs = CPU(cpu);

diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index 2e0224c6af8d12ca47da42a54deb2204f604bb69..4d30e2795177d2150ef1eeba435ef597d922d2de 100644 (file)
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -24,6 +24,7 @@ bool kvmppc_get_host_serial(char **buf);
 int kvmppc_get_hasidle(CPUPPCState *env);
 int kvmppc_get_hypercall(CPUPPCState *env, uint8_t *buf, int buf_len);
 int kvmppc_set_interrupt(PowerPCCPU *cpu, int irq, int level);
+void kvmppc_enable_logical_ci_hcalls(void);
 void kvmppc_set_papr(PowerPCCPU *cpu);
 int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version);
 void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy);
@@ -107,6 +108,10 @@ static inline int kvmppc_set_interrupt(PowerPCCPU *cpu, int irq, int level)
     return -1;
 }
 
+static inline void kvmppc_enable_logical_ci_hcalls(void)
+{
+}
+
 static inline void kvmppc_set_papr(PowerPCCPU *cpu)
 {
 }