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KVM: add kvm_request_pending

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A first step in vcpu->requests encapsulation.  Additionally, we now
use READ_ONCE() when accessing vcpu->requests, which ensures we
always load vcpu->requests when it's accessed.  This is important as
other threads can change it any time.  Also, READ_ONCE() documents
that vcpu->requests is used with other threads, likely requiring
memory barriers, which it does.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[ Documented the new use of READ_ONCE() and converted another check
  in arch/mips/kvm/vz.c ]
Signed-off-by: Andrew Jones <drjones@redhat.com>
Acked-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
This commit is contained in:
Radim Krčmář 2017-06-04 14:43:52 +02:00 • committed by Christoffer Dall
parent 2387149ead
commit 2fa6e1e12a
7 changed files with 13 additions and 9 deletions
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2
arch/mips/kvm/trap_emul.c
View file

@ -1094,7 +1094,7 @@ static void kvm_trap_emul_check_requests(struct kvm_vcpu *vcpu, int cpu,
struct mm_struct *mm; struct mm_struct *mm;
int i; int i;
if (likely(!vcpu->requests)) if (likely(!kvm_request_pending(vcpu)))
return; return;
if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu)) { if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu)) {

2
arch/mips/kvm/vz.c
View file

@ -2337,7 +2337,7 @@ static int kvm_vz_check_requests(struct kvm_vcpu *vcpu, int cpu)
int ret = 0; int ret = 0;
int i; int i;
if (!vcpu->requests) if (!kvm_request_pending(vcpu))
return 0; return 0;
if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu)) { if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu)) {

2
arch/powerpc/kvm/booke.c
View file

@ -687,7 +687,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
kvmppc_core_check_exceptions(vcpu); kvmppc_core_check_exceptions(vcpu);
if (vcpu->requests) { if (kvm_request_pending(vcpu)) {
/* Exception delivery raised request; start over */ /* Exception delivery raised request; start over */
return 1; return 1;
} }

5
arch/powerpc/kvm/powerpc.c
View file

@ -55,8 +55,7 @@ EXPORT_SYMBOL_GPL(kvmppc_pr_ops);
int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
{ {
return !!(v->arch.pending_exceptions) || return !!(v->arch.pending_exceptions) || kvm_request_pending(v);
v->requests;
} }
int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
@ -108,7 +107,7 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
*/ */
smp_mb(); smp_mb();
if (vcpu->requests) { if (kvm_request_pending(vcpu)) {
/* Make sure we process requests preemptable */ /* Make sure we process requests preemptable */
local_irq_enable(); local_irq_enable();
trace_kvm_check_requests(vcpu); trace_kvm_check_requests(vcpu);

2
arch/s390/kvm/kvm-s390.c
View file

@ -2440,7 +2440,7 @@ static int kvm_s390_handle_requests(struct kvm_vcpu *vcpu)
{ {
retry: retry:
kvm_s390_vcpu_request_handled(vcpu); kvm_s390_vcpu_request_handled(vcpu);
if (!vcpu->requests) if (!kvm_request_pending(vcpu))
return 0; return 0;
/* /*
* We use MMU_RELOAD just to re-arm the ipte notifier for the * We use MMU_RELOAD just to re-arm the ipte notifier for the

4
arch/x86/kvm/x86.c
View file

@ -6710,7 +6710,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
bool req_immediate_exit = false; bool req_immediate_exit = false;
if (vcpu->requests) { if (kvm_request_pending(vcpu)) {
if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu)) if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu))
kvm_mmu_unload(vcpu); kvm_mmu_unload(vcpu);
if (kvm_check_request(KVM_REQ_MIGRATE_TIMER, vcpu)) if (kvm_check_request(KVM_REQ_MIGRATE_TIMER, vcpu))
@ -6874,7 +6874,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_x86_ops->sync_pir_to_irr(vcpu); kvm_x86_ops->sync_pir_to_irr(vcpu);
} }
if (vcpu->mode == EXITING_GUEST_MODE || vcpu->requests if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu)
|| need_resched() || signal_pending(current)) { || need_resched() || signal_pending(current)) {
vcpu->mode = OUTSIDE_GUEST_MODE; vcpu->mode = OUTSIDE_GUEST_MODE;
smp_wmb(); smp_wmb();

5
include/linux/kvm_host.h
View file

@ -1105,6 +1105,11 @@ static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu)
set_bit(req & KVM_REQUEST_MASK, &vcpu->requests); set_bit(req & KVM_REQUEST_MASK, &vcpu->requests);
} }
static inline bool kvm_request_pending(struct kvm_vcpu *vcpu)
{
return READ_ONCE(vcpu->requests);
}
static inline bool kvm_test_request(int req, struct kvm_vcpu *vcpu) static inline bool kvm_test_request(int req, struct kvm_vcpu *vcpu)
{ {
return test_bit(req & KVM_REQUEST_MASK, &vcpu->requests); return test_bit(req & KVM_REQUEST_MASK, &vcpu->requests);