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KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt()

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Factor out the "block" part of kvm_vcpu_halt() so that x86 can emulate
non-halt wait/sleep/block conditions that should not be subjected to
halt-polling.

No functional change intended.

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-10-08 19:12:07 -07:00 committed by Paolo Bonzini
parent 91b99ea706
commit fac4268894
2 changed files with 37 additions and 16 deletions
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1
include/linux/kvm_host.h
View File

@ -1103,6 +1103,7 @@ void kvm_sigset_activate(struct kvm_vcpu *vcpu);
void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);
void kvm_vcpu_halt(struct kvm_vcpu *vcpu);
bool kvm_vcpu_block(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu);
bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu);

52
virt/kvm/kvm_main.c
View File

@ -3272,6 +3272,35 @@ out:
return ret;
}
/*
* Block the vCPU until the vCPU is runnable, an event arrives, or a signal is
* pending. This is mostly used when halting a vCPU, but may also be used
* directly for other vCPU non-runnable states, e.g. x86's Wait-For-SIPI.
*/
bool kvm_vcpu_block(struct kvm_vcpu *vcpu)
{
struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
bool waited = false;
kvm_arch_vcpu_blocking(vcpu);
prepare_to_rcuwait(wait);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
if (kvm_vcpu_check_block(vcpu) < 0)
break;
waited = true;
schedule();
}
finish_rcuwait(wait);
kvm_arch_vcpu_unblocking(vcpu);
return waited;
}
static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
ktime_t end, bool success)
{
@ -3294,9 +3323,14 @@ static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
}
}
/*
* Emulate a vCPU halt condition, e.g. HLT on x86, WFI on arm, etc... If halt
* polling is enabled, busy wait for a short time before blocking to avoid the
* expensive block+unblock sequence if a wake event arrives soon after the vCPU
* is halted.
*/
void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
{
struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
bool halt_poll_allowed = !kvm_arch_no_poll(vcpu);
bool do_halt_poll = halt_poll_allowed && vcpu->halt_poll_ns;
ktime_t start, cur, poll_end;
@ -3319,21 +3353,7 @@ void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
} while (kvm_vcpu_can_poll(cur, stop));
}
kvm_arch_vcpu_blocking(vcpu);
prepare_to_rcuwait(wait);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
if (kvm_vcpu_check_block(vcpu) < 0)
break;
waited = true;
schedule();
}
finish_rcuwait(wait);
kvm_arch_vcpu_unblocking(vcpu);
waited = kvm_vcpu_block(vcpu);
cur = ktime_get();
if (waited) {