POWER9 CPUs have independent MMU contexts per thread so KVM
does not have to bring sibling threads into real-mode when
switching MMU mode to guest. This can simplify POWER9 sleep/wake
paths and avoids hwsyncs.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/include/asm/kvm_book3s_asm.h | 4 ++++
arch/powerpc/kernel/idle_book3s.S | 8 ++-----
arch/powerpc/kvm/book3s_hv.c | 37 ++++++++++++++++++++++++++-----
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 8 +++++++
4 files changed, 46 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s_asm.h
b/arch/powerpc/include/asm/kvm_book3s_asm.h
index 7cea76f11c26..83596f32f50b 100644
--- a/arch/powerpc/include/asm/kvm_book3s_asm.h
+++ b/arch/powerpc/include/asm/kvm_book3s_asm.h
@@ -104,6 +104,10 @@ struct kvmppc_host_state {
u8 napping;
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+ /*
+ * hwthread_req/hwthread_state pair is used to pull sibling threads
+ * out of guest on pre-ISAv3.0B CPUs where threads share MMU.
+ */
u8 hwthread_req;
u8 hwthread_state;
u8 host_ipi;
diff --git a/arch/powerpc/kernel/idle_book3s.S
b/arch/powerpc/kernel/idle_book3s.S
index e6252c5a57a4..3ab73f9223e4 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -243,12 +243,6 @@ enter_winkle:
* r3 - PSSCR value corresponding to the requested stop state.
*/
power_enter_stop:
-#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
- /* Tell KVM we're entering idle */
- li r4,KVM_HWTHREAD_IN_IDLE
- /* DO THIS IN REAL MODE! See comment above. */
- stb r4,HSTATE_HWTHREAD_STATE(r13)
-#endif
/*
* Check if we are executing the lite variant with ESL=EC=0
*/
@@ -435,6 +429,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
mr r3,r12
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+BEGIN_FTR_SECTION
li r0,KVM_HWTHREAD_IN_KERNEL
stb r0,HSTATE_HWTHREAD_STATE(r13)
/* Order setting hwthread_state vs. testing hwthread_req */
@@ -444,6 +439,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
beq 1f
b kvm_start_guest
1:
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
#endif
/* Return SRR1 from power7_nap() */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 359c79cdf0cc..bb1ab14f963a 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2111,6 +2111,16 @@ static int kvmppc_grab_hwthread(int cpu)
struct paca_struct *tpaca;
long timeout = 10000;
+ /*
+ * ISA v3.0 idle routines do not set hwthread_state or test
+ * hwthread_req, so they can not grab idle threads.
+ */
+ if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+ WARN_ON(1);
+ pr_err("KVM: can not control sibling threads\n");
+ return -EBUSY;
+ }
+
tpaca = &paca[cpu];
/* Ensure the thread won't go into the kernel if it wakes */
@@ -2145,12 +2155,26 @@ static void kvmppc_release_hwthread(int cpu)
struct paca_struct *tpaca;
tpaca = &paca[cpu];
- tpaca->kvm_hstate.hwthread_req = 0;
tpaca->kvm_hstate.kvm_vcpu = NULL;
tpaca->kvm_hstate.kvm_vcore = NULL;
tpaca->kvm_hstate.kvm_split_mode = NULL;
}
+static void kvmppc_release_hwthread_secondary(int cpu)
+{
+ struct paca_struct *tpaca;
+
+ if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+ WARN_ON(1);
+ return;
+ }
+
+ tpaca = &paca[cpu];
+ tpaca->kvm_hstate.hwthread_req = 0;
+ kvmppc_release_hwthread(cpu);
+}
+
+
static void radix_flush_cpu(struct kvm *kvm, int cpu, struct kvm_vcpu *vcpu)
{
int i;
@@ -2274,7 +2298,7 @@ static int on_primary_thread(void)
if (kvmppc_grab_hwthread(cpu + thr)) {
/* Couldn't grab one; let the others go */
do {
- kvmppc_release_hwthread(cpu + thr);
+ kvmppc_release_hwthread_secondary(cpu + thr);
} while (--thr > 0);
return 0;
}
@@ -2702,8 +2726,9 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore
*vc)
kvmppc_vcore_preempt(pvc);
spin_unlock(&pvc->lock);
}
- for (i = 0; i < controlled_threads; ++i)
- kvmppc_release_hwthread(pcpu + i);
+ for (i = 1; i < controlled_threads; ++i)
+ kvmppc_release_hwthread_secondary(pcpu + i);
+ kvmppc_release_hwthread(pcpu);
return;
}
@@ -2858,11 +2883,13 @@ static noinline void kvmppc_run_core(struct
kvmppc_vcore *vc)
/* Let secondaries go back to the offline loop */
for (i = 0; i < controlled_threads; ++i) {
- kvmppc_release_hwthread(pcpu + i);
if (sip && sip->napped[i])
kvmppc_ipi_thread(pcpu + i);
cpumask_clear_cpu(pcpu + i, &vc->kvm->arch.cpu_in_guest);
}
+ for (i = 1; i < controlled_threads; ++i)
+ kvmppc_release_hwthread_secondary(pcpu + i);
+ kvmppc_release_hwthread(pcpu);
spin_unlock(&vc->lock);
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index c52184a8efdf..3e024fd71fe8 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -149,9 +149,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
subf r4, r4, r3
mtspr SPRN_DEC, r4
+BEGIN_FTR_SECTION
/* hwthread_req may have got set by cede or no vcpu, so clear it */
li r0, 0
stb r0, HSTATE_HWTHREAD_REQ(r13)
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
/*
* For external interrupts we need to call the Linux
@@ -314,6 +316,7 @@ kvm_novcpu_exit:
* Relocation is off and most register values are lost.
* r13 points to the PACA.
* r3 contains the SRR1 wakeup value, SRR1 is trashed.
+ * This is not used by ISAv3.0B processors.
*/
.globl kvm_start_guest
kvm_start_guest:
@@ -432,6 +435,9 @@ kvm_secondary_got_guest:
* While waiting we also need to check if we get given a vcpu to run.
*/
kvm_no_guest:
+BEGIN_FTR_SECTION
+ twi 31,0,0
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
lbz r3, HSTATE_HWTHREAD_REQ(r13)
cmpwi r3, 0
bne 53f
@@ -2509,8 +2515,10 @@ kvm_do_nap:
clrrdi r0, r0, 1
mtspr SPRN_CTRLT, r0
+BEGIN_FTR_SECTION
li r0,1
stb r0,HSTATE_HWTHREAD_REQ(r13)
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
mfspr r5,SPRN_LPCR
ori r5,r5,LPCR_PECE0 | LPCR_PECE1
BEGIN_FTR_SECTION
--
2.11.0
