From d588bb9be1da6aa750aa64875fe57369db983d8b Mon Sep 17 00:00:00 2001 From: Chao Gao Date: Tue, 19 Apr 2022 23:45:10 +0800 Subject: KVM: VMX: enable IPI virtualization With IPI virtualization enabled, the processor emulates writes to APIC registers that would send IPIs. The processor sets the bit corresponding to the vector in target vCPU's PIR and may send a notification (IPI) specified by NDST and NV fields in target vCPU's Posted-Interrupt Descriptor (PID). It is similar to what IOMMU engine does when dealing with posted interrupt from devices. A PID-pointer table is used by the processor to locate the PID of a vCPU with the vCPU's APIC ID. The table size depends on maximum APIC ID assigned for current VM session from userspace. Allocating memory for PID-pointer table is deferred to vCPU creation, because irqchip mode and VM-scope maximum APIC ID is settled at that point. KVM can skip PID-pointer table allocation if !irqchip_in_kernel(). Like VT-d PI, if a vCPU goes to blocked state, VMM needs to switch its notification vector to wakeup vector. This can ensure that when an IPI for blocked vCPUs arrives, VMM can get control and wake up blocked vCPUs. And if a VCPU is preempted, its posted interrupt notification is suppressed. Note that IPI virtualization can only virualize physical-addressing, flat mode, unicast IPIs. Sending other IPIs would still cause a trap-like APIC-write VM-exit and need to be handled by VMM. Signed-off-by: Chao Gao Signed-off-by: Zeng Guang Message-Id: <20220419154510.11938-1-guang.zeng@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/posted_intr.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kvm/vmx/posted_intr.h') diff --git a/arch/x86/kvm/vmx/posted_intr.h b/arch/x86/kvm/vmx/posted_intr.h index 9a45d5c9f116..26992076552e 100644 --- a/arch/x86/kvm/vmx/posted_intr.h +++ b/arch/x86/kvm/vmx/posted_intr.h @@ -5,6 +5,8 @@ #define POSTED_INTR_ON 0 #define POSTED_INTR_SN 1 +#define PID_TABLE_ENTRY_VALID 1 + /* Posted-Interrupt Descriptor */ struct pi_desc { u32 pir[8]; /* Posted interrupt requested */ -- cgit v1.2.3