@@ -272,8 +272,6 @@ struct kvmppc_vcore {
int n_runnable;
int num_threads;
int entry_exit_count;
- int n_woken;
- int nap_count;
int napping_threads;
int first_vcpuid;
u16 pcpu;
@@ -563,7 +563,6 @@ int main(void)
DEFINE(VCPU_WORT, offsetof(struct kvm_vcpu, arch.wort));
DEFINE(VCPU_SHADOW_SRR1, offsetof(struct kvm_vcpu, arch.shadow_srr1));
DEFINE(VCORE_ENTRY_EXIT, offsetof(struct kvmppc_vcore, entry_exit_count));
- DEFINE(VCORE_NAP_COUNT, offsetof(struct kvmppc_vcore, nap_count));
DEFINE(VCORE_IN_GUEST, offsetof(struct kvmppc_vcore, in_guest));
DEFINE(VCORE_NAPPING_THREADS, offsetof(struct kvmppc_vcore, napping_threads));
DEFINE(VCORE_KVM, offsetof(struct kvmppc_vcore, kvm));
@@ -1729,8 +1729,10 @@ static int kvmppc_grab_hwthread(int cpu)
tpaca = &paca[cpu];
/* Ensure the thread won't go into the kernel if it wakes */
- tpaca->kvm_hstate.hwthread_req = 1;
tpaca->kvm_hstate.kvm_vcpu = NULL;
+ tpaca->kvm_hstate.napping = 0;
+ smp_wmb();
+ tpaca->kvm_hstate.hwthread_req = 1;
/*
* If the thread is already executing in the kernel (e.g. handling
@@ -1773,35 +1775,43 @@ static void kvmppc_start_thread(struct kvm_vcpu *vcpu)
}
cpu = vc->pcpu + vcpu->arch.ptid;
tpaca = &paca[cpu];
- tpaca->kvm_hstate.kvm_vcpu = vcpu;
tpaca->kvm_hstate.kvm_vcore = vc;
tpaca->kvm_hstate.ptid = vcpu->arch.ptid;
vcpu->cpu = vc->pcpu;
+ /* Order stores to hstate.kvm_vcore etc. before store to kvm_vcpu */
smp_wmb();
+ tpaca->kvm_hstate.kvm_vcpu = vcpu;
#if defined(CONFIG_PPC_ICP_NATIVE) && defined(CONFIG_SMP)
- if (cpu != smp_processor_id()) {
+ if (cpu != smp_processor_id())
xics_wake_cpu(cpu);
- if (vcpu->arch.ptid)
- ++vc->n_woken;
- }
#endif
}
-static void kvmppc_wait_for_nap(struct kvmppc_vcore *vc)
+static void kvmppc_wait_for_nap(void)
{
- int i;
+ int cpu = smp_processor_id();
+ int i, loops;
- HMT_low();
- i = 0;
- while (vc->nap_count < vc->n_woken) {
- if (++i >= 1000000) {
- pr_err("kvmppc_wait_for_nap timeout %d %d\n",
- vc->nap_count, vc->n_woken);
- break;
+ for (loops = 0; loops < 1000000; ++loops) {
+ /*
+ * Check if all threads are finished.
+ * We set the vcpu pointer when starting a thread
+ * and the thread clears it when finished, so we look
+ * for any threads that still have a non-NULL vcpu ptr.
+ */
+ for (i = 1; i < threads_per_subcore; ++i)
+ if (paca[cpu + i].kvm_hstate.kvm_vcpu)
+ break;
+ if (i == threads_per_subcore) {
+ HMT_medium();
+ return;
}
- cpu_relax();
+ HMT_low();
}
HMT_medium();
+ for (i = 1; i < threads_per_subcore; ++i)
+ if (paca[cpu + i].kvm_hstate.kvm_vcpu)
+ pr_err("KVM: CPU %d seems to be stuck\n", cpu + i);
}
/*
@@ -1942,8 +1952,6 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
/*
* Initialize *vc.
*/
- vc->n_woken = 0;
- vc->nap_count = 0;
vc->entry_exit_count = 0;
vc->preempt_tb = TB_NIL;
vc->in_guest = 0;
@@ -2002,8 +2010,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
vcpu->cpu = -1;
/* wait for secondary threads to finish writing their state to memory */
- if (vc->nap_count < vc->n_woken)
- kvmppc_wait_for_nap(vc);
+ kvmppc_wait_for_nap();
for (i = 0; i < threads_per_subcore; ++i)
kvmppc_release_hwthread(vc->pcpu + i);
/* prevent other vcpu threads from doing kvmppc_start_thread() now */
@@ -292,26 +292,21 @@ kvm_secondary_got_guest:
ld r6, PACA_DSCR(r13)
std r6, HSTATE_DSCR(r13)
+ /* Order load of vcore, ptid etc. after load of vcpu */
+ lwsync
bl kvmppc_hv_entry
/* Back from the guest, go back to nap */
/* Clear our vcpu pointer so we don't come back in early */
li r0, 0
- std r0, HSTATE_KVM_VCPU(r13)
/*
- * Make sure we clear HSTATE_KVM_VCPU(r13) before incrementing
- * the nap_count, because once the increment to nap_count is
- * visible we could be given another vcpu.
+ * Once we clear HSTATE_KVM_VCPU(r13), the code in
+ * kvmppc_run_core() is going to assume that all our vcpu
+ * state is visible in memory. This lwsync makes sure
+ * that that is true.
*/
lwsync
-
- /* increment the nap count and then go to nap mode */
- ld r4, HSTATE_KVM_VCORE(r13)
- addi r4, r4, VCORE_NAP_COUNT
-51: lwarx r3, 0, r4
- addi r3, r3, 1
- stwcx. r3, 0, r4
- bne 51b
+ std r0, HSTATE_KVM_VCPU(r13)
/*
* At this point we have finished executing in the guest.
We can tell when a secondary thread has finished running a guest by the fact that it clears its kvm_hstate.kvm_vcpu pointer, so there is no real need for the nap_count field in the kvmppc_vcore struct. This changes kvmppc_wait_for_nap to poll the kvm_hstate.kvm_vcpu pointers of the secondary threads rather than polling vc->nap_count. Besides reducing the size of the kvmppc_vcore struct by 8 bytes, this also means that we can tell which secondary threads have got stuck and thus print a more informative error message. Signed-off-by: Paul Mackerras <paulus@samba.org> --- arch/powerpc/include/asm/kvm_host.h | 2 -- arch/powerpc/kernel/asm-offsets.c | 1 - arch/powerpc/kvm/book3s_hv.c | 47 +++++++++++++++++++-------------- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 19 +++++-------- 4 files changed, 34 insertions(+), 35 deletions(-)