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kvm: First step to push iothread lock out of inner run loop

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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.

Regarding pre/post-run callbacks, s390x and ARM should be fine without
specific locking as the callbacks are empty. MIPS and POWER require
locking for the pre-run callback.

For the handle_exit callback, it is non-empty in x86, POWER and s390.
Some POWER cases could do without the locking, but it is left in
place for now.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1434646046-27150-7-git-send-email-pbonzini@redhat.com>
This commit is contained in:
Jan Kiszka 2015-06-18 18:47:23 +02:00 • committed by Paolo Bonzini
parent 4840f10eff
commit 4b8523ee89
5 changed files with 46 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

7
target-ppc/kvm.c
View file

@ -1242,6 +1242,8 @@ 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 &&
@ -1269,6 +1271,8 @@ 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();
}
MemTxAttrs kvm_arch_post_run(CPUState *cs, struct kvm_run *run)
@ -1570,6 +1574,8 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
CPUPPCState *env = &cpu->env;
int ret;
qemu_mutex_lock_iothread();
switch (run->exit_reason) {
case KVM_EXIT_DCR:
if (run->dcr.is_write) {
@ -1620,6 +1626,7 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
break;
}
qemu_mutex_unlock_iothread();
return ret;
}