From: Jan Kiszka <jan.kis...@siemens.com>
This opens the path to get rid of the iothread lock on vmexits in KVM
mode. On x86, the in-kernel irqchips has to be used because we otherwise
need to synchronize APIC and other per-cpu state accesses that could be
changed concurrently.
s390x and ARM should be fine without specific locking as their
pre/post-run callbacks are empty. MIPS and POWER require locking for
the pre-run callback.
Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
kvm-all.c | 14 ++++++++++++--
target-i386/kvm.c | 18 ++++++++++++++++++
target-mips/kvm.c | 4 ++++
target-ppc/kvm.c | 4 ++++
4 files changed, 38 insertions(+), 2 deletions(-)
diff --git a/kvm-all.c b/kvm-all.c
index 55025cc..8da1deb 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1765,6 +1765,8 @@ int kvm_cpu_exec(CPUState *cpu)
return EXCP_HLT;
}
+ qemu_mutex_unlock_iothread();
+
do {
if (cpu->kvm_vcpu_dirty) {
kvm_arch_put_registers(cpu, KVM_PUT_RUNTIME_STATE);
@@ -1781,11 +1783,9 @@ int kvm_cpu_exec(CPUState *cpu)
*/
qemu_cpu_kick_self();
}
- qemu_mutex_unlock_iothread();
run_ret = kvm_vcpu_ioctl(cpu, KVM_RUN, 0);
- qemu_mutex_lock_iothread();
kvm_arch_post_run(cpu, run);
if (run_ret < 0) {
@@ -1804,19 +1804,23 @@ int kvm_cpu_exec(CPUState *cpu)
switch (run->exit_reason) {
case KVM_EXIT_IO:
DPRINTF("handle_io\n");
+ qemu_mutex_lock_iothread();
kvm_handle_io(run->io.port,
(uint8_t *)run + run->io.data_offset,
run->io.direction,
run->io.size,
run->io.count);
+ qemu_mutex_unlock_iothread();
ret = 0;
break;
case KVM_EXIT_MMIO:
DPRINTF("handle_mmio\n");
+ qemu_mutex_lock_iothread();
cpu_physical_memory_rw(run->mmio.phys_addr,
run->mmio.data,
run->mmio.len,
run->mmio.is_write);
+ qemu_mutex_unlock_iothread();
ret = 0;
break;
case KVM_EXIT_IRQ_WINDOW_OPEN:
@@ -1825,7 +1829,9 @@ int kvm_cpu_exec(CPUState *cpu)
break;
case KVM_EXIT_SHUTDOWN:
DPRINTF("shutdown\n");
+ qemu_mutex_lock_iothread();
qemu_system_reset_request();
+ qemu_mutex_unlock_iothread();
ret = EXCP_INTERRUPT;
break;
case KVM_EXIT_UNKNOWN:
@@ -1854,11 +1860,15 @@ int kvm_cpu_exec(CPUState *cpu)
break;
default:
DPRINTF("kvm_arch_handle_exit\n");
+ qemu_mutex_lock_iothread();
ret = kvm_arch_handle_exit(cpu, run);
+ qemu_mutex_unlock_iothread();
break;
}
} while (ret == 0);
+ qemu_mutex_lock_iothread();
+
if (ret < 0) {
cpu_dump_state(cpu, stderr, fprintf, CPU_DUMP_CODE);
vm_stop(RUN_STATE_INTERNAL_ERROR);
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 41d09e5..94cff8c 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -2191,7 +2191,10 @@ void kvm_arch_pre_run(CPUState *cpu, struct kvm_run *run)
/* Inject NMI */
if (cpu->interrupt_request & CPU_INTERRUPT_NMI) {
+ qemu_mutex_lock_iothread();
cpu->interrupt_request &= ~CPU_INTERRUPT_NMI;
+ qemu_mutex_unlock_iothread();
+
DPRINTF("injected NMI\n");
ret = kvm_vcpu_ioctl(cpu, KVM_NMI);
if (ret < 0) {
@@ -2200,6 +2203,10 @@ void kvm_arch_pre_run(CPUState *cpu, struct kvm_run *run)
}
}
+ if (!kvm_irqchip_in_kernel()) {
+ qemu_mutex_lock_iothread();
+ }
+
/* Force the VCPU out of its inner loop to process any INIT requests
* or (for userspace APIC, but it is cheap to combine the checks here)
* pending TPR access reports.
@@ -2243,6 +2250,8 @@ void kvm_arch_pre_run(CPUState *cpu, struct kvm_run *run)
DPRINTF("setting tpr\n");
run->cr8 = cpu_get_apic_tpr(x86_cpu->apic_state);
+
+ qemu_mutex_unlock_iothread();
}
}
@@ -2256,8 +2265,17 @@ void kvm_arch_post_run(CPUState *cpu, struct kvm_run
*run)
} else {
env->eflags &= ~IF_MASK;
}
+
+ /* We need to protect the apic state against concurrent accesses from
+ * different threads in case the userspace irqchip is used. */
+ if (!kvm_irqchip_in_kernel()) {
+ qemu_mutex_lock_iothread();
+ }
cpu_set_apic_tpr(x86_cpu->apic_state, run->cr8);
cpu_set_apic_base(x86_cpu->apic_state, run->apic_base);
+ if (!kvm_irqchip_in_kernel()) {
+ qemu_mutex_unlock_iothread();
+ }
}
int kvm_arch_process_async_events(CPUState *cs)
diff --git a/target-mips/kvm.c b/target-mips/kvm.c
index 4d1f7ea..7f02be7 100644
--- a/target-mips/kvm.c
+++ b/target-mips/kvm.c
@@ -98,6 +98,8 @@ void kvm_arch_pre_run(CPUState *cs, struct kvm_run *run)
int r;
struct kvm_mips_interrupt intr;
+ qemu_mutex_lock_iothread();
+
if ((cs->interrupt_request & CPU_INTERRUPT_HARD) &&
cpu_mips_io_interrupts_pending(cpu)) {
intr.cpu = -1;
@@ -108,6 +110,8 @@ void kvm_arch_pre_run(CPUState *cs, struct kvm_run *run)
__func__, cs->cpu_index, intr.irq);
}
}
+
+ qemu_mutex_unlock_iothread();
}
void kvm_arch_post_run(CPUState *cs, struct kvm_run *run)
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 12328a4..ce2498a 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -1241,6 +1241,8 @@ void kvm_arch_pre_run(CPUState *cs, struct kvm_run *run)
int r;
unsigned irq;
+ qemu_mutex_lock_iothread();
+
/* PowerPC QEMU tracks the various core input pins (interrupt, critical
* interrupt, reset, etc) in PPC-specific env->irq_input_state. */
if (!cap_interrupt_level &&
@@ -1268,6 +1270,8 @@ void kvm_arch_pre_run(CPUState *cs, struct kvm_run *run)
/* We don't know if there are more interrupts pending after this. However,
* the guest will return to userspace in the course of handling this one
* anyways, so we will get a chance to deliver the rest. */
+
+ qemu_mutex_unlock_iothread();
}
void kvm_arch_post_run(CPUState *cpu, struct kvm_run *run)
--
2.3.0
