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For VMX, when a vcpu enters HLT emulation, pi_post_block will: 1) Add vcpu to per-cpu list of blocked vcpus. 2) Program the posted-interrupt descriptor "notification vector" to POSTED_INTR_WAKEUP_VECTOR With interrupt remapping, an interrupt will set the PIR bit for the vector programmed for the device on the CPU, test-and-set the ON bit on the posted interrupt descriptor, and if the ON bit is clear generate an interrupt for the notification vector. This way, the target CPU wakes upon a device interrupt and wakes up the target vcpu. Problem is that pi_post_block only programs the notification vector if kvm_arch_has_assigned_device() is true. Its possible for the following to happen: 1) vcpu V HLTs on pcpu P, kvm_arch_has_assigned_device is false, notification vector is not programmed 2) device is assigned to VM 3) device interrupts vcpu V, sets ON bit (notification vector not programmed, so pcpu P remains in idle) 4) vcpu 0 IPIs vcpu V (in guest), but since pi descriptor ON bit is set, kvm_vcpu_kick is skipped 5) vcpu 0 busy spins on vcpu V's response for several seconds, until RCU watchdog NMIs all vCPUs. To fix this, use the start_assignment kvm_x86_ops callback to kick vcpus out of the halt loop, so the notification vector is properly reprogrammed to the wakeup vector. Reported-by: Pei Zhang <pezhang@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Message-Id: <20210526172014.GA29007@fuller.cnet> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
101 lines
2.4 KiB
C
101 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __KVM_X86_VMX_POSTED_INTR_H
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#define __KVM_X86_VMX_POSTED_INTR_H
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#define POSTED_INTR_ON 0
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#define POSTED_INTR_SN 1
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/* Posted-Interrupt Descriptor */
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struct pi_desc {
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u32 pir[8]; /* Posted interrupt requested */
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union {
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struct {
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/* bit 256 - Outstanding Notification */
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u16 on : 1,
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/* bit 257 - Suppress Notification */
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sn : 1,
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/* bit 271:258 - Reserved */
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rsvd_1 : 14;
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/* bit 279:272 - Notification Vector */
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u8 nv;
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/* bit 287:280 - Reserved */
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u8 rsvd_2;
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/* bit 319:288 - Notification Destination */
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u32 ndst;
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};
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u64 control;
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};
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u32 rsvd[6];
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} __aligned(64);
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static inline bool pi_test_and_set_on(struct pi_desc *pi_desc)
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{
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return test_and_set_bit(POSTED_INTR_ON,
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(unsigned long *)&pi_desc->control);
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}
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static inline bool pi_test_and_clear_on(struct pi_desc *pi_desc)
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{
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return test_and_clear_bit(POSTED_INTR_ON,
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(unsigned long *)&pi_desc->control);
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}
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static inline int pi_test_and_set_pir(int vector, struct pi_desc *pi_desc)
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{
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return test_and_set_bit(vector, (unsigned long *)pi_desc->pir);
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}
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static inline bool pi_is_pir_empty(struct pi_desc *pi_desc)
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{
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return bitmap_empty((unsigned long *)pi_desc->pir, NR_VECTORS);
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}
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static inline void pi_set_sn(struct pi_desc *pi_desc)
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{
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set_bit(POSTED_INTR_SN,
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(unsigned long *)&pi_desc->control);
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}
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static inline void pi_set_on(struct pi_desc *pi_desc)
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{
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set_bit(POSTED_INTR_ON,
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(unsigned long *)&pi_desc->control);
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}
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static inline void pi_clear_on(struct pi_desc *pi_desc)
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{
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clear_bit(POSTED_INTR_ON,
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(unsigned long *)&pi_desc->control);
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}
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static inline void pi_clear_sn(struct pi_desc *pi_desc)
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{
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clear_bit(POSTED_INTR_SN,
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(unsigned long *)&pi_desc->control);
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}
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static inline int pi_test_on(struct pi_desc *pi_desc)
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{
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return test_bit(POSTED_INTR_ON,
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(unsigned long *)&pi_desc->control);
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}
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static inline int pi_test_sn(struct pi_desc *pi_desc)
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{
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return test_bit(POSTED_INTR_SN,
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(unsigned long *)&pi_desc->control);
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}
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void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu);
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void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu);
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int pi_pre_block(struct kvm_vcpu *vcpu);
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void pi_post_block(struct kvm_vcpu *vcpu);
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void pi_wakeup_handler(void);
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void __init pi_init_cpu(int cpu);
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bool pi_has_pending_interrupt(struct kvm_vcpu *vcpu);
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int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq,
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bool set);
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void vmx_pi_start_assignment(struct kvm *kvm);
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#endif /* __KVM_X86_VMX_POSTED_INTR_H */
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