@@ -289,6 +289,7 @@ struct kvmppc_vcore {
ulong dpdes; /* doorbell state (POWER8) */
void *mpp_buffer; /* Micro Partition Prefetch buffer */
bool mpp_buffer_is_valid;
+ ulong conferring_threads;
};
#define VCORE_ENTRY_COUNT(vc) ((vc)->entry_exit_count & 0xff)
@@ -604,10 +604,45 @@ static int kvmppc_h_set_mode(struct kvm_vcpu *vcpu, unsigned long mflags,
}
}
+static int kvm_arch_vcpu_yield_to(struct kvm_vcpu *target)
+{
+ struct kvmppc_vcore *vcore = target->arch.vcore;
+
+ /*
+ * We expect to have been called by the real mode handler
+ * (kvmppc_rm_h_confer()) which would have directly returned
+ * H_SUCCESS if the source vcore wasn't idle (e.g. if it may
+ * have useful work to do and should not confer) so we don't
+ * recheck that here.
+ */
+
+ spin_lock(&vcore->lock);
+ if (target->arch.state == KVMPPC_VCPU_RUNNABLE &&
+ vcore->vcore_state != VCORE_INACTIVE)
+ target = vcore->runner;
+ spin_unlock(&vcore->lock);
+
+ return kvm_vcpu_yield_to(target);
+}
+
+static int kvmppc_get_yield_count(struct kvm_vcpu *vcpu)
+{
+ int yield_count = 0;
+ struct lppaca *lppaca;
+
+ spin_lock(&vcpu->arch.vpa_update_lock);
+ lppaca = (struct lppaca *)vcpu->arch.vpa.pinned_addr;
+ if (lppaca)
+ yield_count = lppaca->yield_count;
+ spin_unlock(&vcpu->arch.vpa_update_lock);
+ return yield_count;
+}
+
int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
{
unsigned long req = kvmppc_get_gpr(vcpu, 3);
unsigned long target, ret = H_SUCCESS;
+ int yield_count;
struct kvm_vcpu *tvcpu;
int idx, rc;
@@ -643,7 +678,10 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
ret = H_PARAMETER;
break;
}
- kvm_vcpu_yield_to(tvcpu);
+ yield_count = kvmppc_get_gpr(vcpu, 5);
+ if (kvmppc_get_yield_count(tvcpu) != yield_count)
+ break;
+ kvm_arch_vcpu_yield_to(tvcpu);
break;
case H_REGISTER_VPA:
ret = do_h_register_vpa(vcpu, kvmppc_get_gpr(vcpu, 4),
@@ -1692,6 +1730,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
vc->vcore_state = VCORE_STARTING;
vc->in_guest = 0;
vc->napping_threads = 0;
+ vc->conferring_threads = 0;
/*
* Updating any of the vpas requires calling kvmppc_pin_guest_page,
@@ -17,6 +17,7 @@
#include <linux/memblock.h>
#include <linux/sizes.h>
#include <linux/cma.h>
+#include <linux/bitops.h>
#include <asm/cputable.h>
#include <asm/kvm_ppc.h>
@@ -97,6 +98,37 @@ void __init kvm_cma_reserve(void)
}
/*
+ * Real-mode H_CONFER implementation.
+ * We check if we are the only vcpu out of this virtual core
+ * still running in the guest and not ceded. If so, we pop up
+ * to the virtual-mode implementation; if not, just return to
+ * the guest.
+ */
+long int kvmppc_rm_h_confer(struct kvm_vcpu *vcpu, int target,
+ unsigned int yield_count)
+{
+ struct kvmppc_vcore *vc = vcpu->arch.vcore;
+ int threads_running;
+ int threads_ceded;
+ int threads_conferring;
+ u64 stop = get_tb() + 10 * tb_ticks_per_usec;
+ int rv = H_SUCCESS; /* => don't yield */
+
+ set_bit(vcpu->arch.ptid, &vc->conferring_threads);
+ while ((get_tb() < stop) && (VCORE_EXIT_COUNT(vc) == 0)) {
+ threads_running = VCORE_ENTRY_COUNT(vc);
+ threads_ceded = hweight32(vc->napping_threads);
+ threads_conferring = hweight32(vc->conferring_threads);
+ if (threads_ceded + threads_conferring >= threads_running) {
+ rv = H_TOO_HARD; /* => do yield */
+ break;
+ }
+ }
+ clear_bit(vcpu->arch.ptid, &vc->conferring_threads);
+ return rv;
+}
+
+/*
* When running HV mode KVM we need to block certain operations while KVM VMs
* exist in the system. We use a counter of VMs to track this.
*
@@ -1798,7 +1798,7 @@ hcall_real_table:
.long 0 /* 0xd8 */
.long 0 /* 0xdc */
.long DOTSYM(kvmppc_h_cede) - hcall_real_table
- .long 0 /* 0xe4 */
+ .long DOTSYM(kvmppc_rm_h_confer) - hcall_real_table
.long 0 /* 0xe8 */
.long 0 /* 0xec */
.long 0 /* 0xf0 */