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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

10
kvm-all.c
View file

@ -1755,6 +1755,8 @@ int kvm_cpu_exec(CPUState *cpu)
return EXCP_HLT;
}
qemu_mutex_unlock_iothread();
do {
MemTxAttrs attrs;
@ -1773,11 +1775,9 @@ 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();
attrs = kvm_arch_post_run(cpu, run);
if (run_ret < 0) {
@ -1804,20 +1804,24 @@ 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, attrs,
(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();
address_space_rw(&address_space_memory,
run->mmio.phys_addr, attrs,
run->mmio.data,
run->mmio.len,
run->mmio.is_write);
qemu_mutex_unlock_iothread();
ret = 0;
break;
case KVM_EXIT_IRQ_WINDOW_OPEN:
@ -1860,6 +1864,8 @@ int kvm_cpu_exec(CPUState *cpu)
}
} 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);