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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
Show Stats 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);

24
target-i386/kvm.c
View File

@ -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 @@ MemTxAttrs 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();
}
return cpu_get_mem_attrs(env);
}
@ -2550,13 +2568,17 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
switch (run->exit_reason) {
case KVM_EXIT_HLT:
DPRINTF("handle_hlt\n");
qemu_mutex_lock_iothread();
ret = kvm_handle_halt(cpu);
qemu_mutex_unlock_iothread();
break;
case KVM_EXIT_SET_TPR:
ret = 0;
break;
case KVM_EXIT_TPR_ACCESS:
qemu_mutex_lock_iothread();
ret = kvm_handle_tpr_access(cpu);
qemu_mutex_unlock_iothread();
break;
case KVM_EXIT_FAIL_ENTRY:
code = run->fail_entry.hardware_entry_failure_reason;
@ -2582,7 +2604,9 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
break;
case KVM_EXIT_DEBUG:
DPRINTF("kvm_exit_debug\n");
qemu_mutex_lock_iothread();
ret = kvm_handle_debug(cpu, &run->debug.arch);
qemu_mutex_unlock_iothread();
break;
default:
fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason);

4
target-mips/kvm.c
View File

@ -99,6 +99,8 @@ 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;
@ -109,6 +111,8 @@ void kvm_arch_pre_run(CPUState *cs, struct kvm_run *run)
__func__, cs->cpu_index, intr.irq);
}
}
qemu_mutex_unlock_iothread();
}
MemTxAttrs kvm_arch_post_run(CPUState *cs, struct kvm_run *run)

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;
}

3
target-s390x/kvm.c
View File

@ -2007,6 +2007,8 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
S390CPU *cpu = S390_CPU(cs);
int ret = 0;
qemu_mutex_lock_iothread();
switch (run->exit_reason) {
case KVM_EXIT_S390_SIEIC:
ret = handle_intercept(cpu);
@ -2027,6 +2029,7 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
fprintf(stderr, "Unknown KVM exit: %d\n", run->exit_reason);
break;
}
qemu_mutex_unlock_iothread();
if (ret == 0) {
ret = EXCP_INTERRUPT;