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| author | Paolo Bonzini <pbonzini@redhat.com> | 2022-06-24 11:45:45 -0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-06-24 11:45:45 -0400 |
| commit | 4de5c54f8c806621ab055eeb240877d75d53b208 (patch) | |
| tree | d5d61b408c3ee92b86f0a59ded29d34941a3b151 | |
| parent | 4b88b1a518b337de1252b8180519ca4c00015c9e (diff) | |
| download | linux-stable-4de5c54f8c806621ab055eeb240877d75d53b208.tar.gz linux-stable-4de5c54f8c806621ab055eeb240877d75d53b208.tar.bz2 linux-stable-4de5c54f8c806621ab055eeb240877d75d53b208.zip | |
KVM: nVMX: clean up posted interrupt descriptor try_cmpxchg
Rely on try_cmpxchg64 for re-reading the PID on failure, using READ_ONCE
only right before the first iteration.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/vmx/posted_intr.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c index 73f60aa480fe..1b56c5e5c9fb 100644 --- a/arch/x86/kvm/vmx/posted_intr.c +++ b/arch/x86/kvm/vmx/posted_intr.c @@ -34,7 +34,7 @@ static inline struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu) return &(to_vmx(vcpu)->pi_desc); } -static int pi_try_set_control(struct pi_desc *pi_desc, u64 old, u64 new) +static int pi_try_set_control(struct pi_desc *pi_desc, u64 *pold, u64 new) { /* * PID.ON can be set at any time by a different vCPU or by hardware, @@ -42,7 +42,7 @@ static int pi_try_set_control(struct pi_desc *pi_desc, u64 old, u64 new) * update must be retried with a fresh snapshot an ON change causes * the cmpxchg to fail. */ - if (!try_cmpxchg64(&pi_desc->control, &old, new)) + if (!try_cmpxchg64(&pi_desc->control, pold, new)) return -EBUSY; return 0; @@ -96,8 +96,9 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) if (!x2apic_mode) dest = (dest << 8) & 0xFF00; + old.control = READ_ONCE(pi_desc->control); do { - old.control = new.control = READ_ONCE(pi_desc->control); + new.control = old.control; /* * Clear SN (as above) and refresh the destination APIC ID to @@ -111,7 +112,7 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) * descriptor was modified on "put" to use the wakeup vector. */ new.nv = POSTED_INTR_VECTOR; - } while (pi_try_set_control(pi_desc, old.control, new.control)); + } while (pi_try_set_control(pi_desc, &old.control, new.control)); local_irq_restore(flags); @@ -156,12 +157,12 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu) WARN(pi_desc->sn, "PI descriptor SN field set before blocking"); + old.control = READ_ONCE(pi_desc->control); do { - old.control = new.control = READ_ONCE(pi_desc->control); - /* set 'NV' to 'wakeup vector' */ + new.control = old.control; new.nv = POSTED_INTR_WAKEUP_VECTOR; - } while (pi_try_set_control(pi_desc, old.control, new.control)); + } while (pi_try_set_control(pi_desc, &old.control, new.control)); /* * Send a wakeup IPI to this CPU if an interrupt may have been posted |