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KVM: x86: emulate wait-for-SIPI and SIPI-VMExit

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Background: We have a lightweight HV, it needs INIT-VMExit and
SIPI-VMExit to wake-up APs for guests since it do not monitor
the Local APIC. But currently virtual wait-for-SIPI(WFS) state
is not supported in nVMX, so when running on top of KVM, the L1
HV cannot receive the INIT-VMExit and SIPI-VMExit which cause
the L2 guest cannot wake up the APs.

According to Intel SDM Chapter 25.2 Other Causes of VM Exits,
SIPIs cause VM exits when a logical processor is in
wait-for-SIPI state.

In this patch:
    1. introduce SIPI exit reason,
    2. introduce wait-for-SIPI state for nVMX,
    3. advertise wait-for-SIPI support to guest.

When L1 hypervisor is not monitoring Local APIC, L0 need to emulate
INIT-VMExit and SIPI-VMExit to L1 to emulate INIT-SIPI-SIPI for
L2. L2 LAPIC write would be traped by L0 Hypervisor(KVM), L0 should
emulate the INIT/SIPI vmexit to L1 hypervisor to set proper state
for L2's vcpu state.

Handle procdure:
Source vCPU:
    L2 write LAPIC.ICR(INIT).
    L0 trap LAPIC.ICR write(INIT): inject a latched INIT event to target
       vCPU.
Target vCPU:
    L0 emulate an INIT VMExit to L1 if is guest mode.
    L1 set guest VMCS, guest_activity_state=WAIT_SIPI, vmresume.
    L0 set vcpu.mp_state to INIT_RECEIVED if (vmcs12.guest_activity_state
       == WAIT_SIPI).

Source vCPU:
    L2 write LAPIC.ICR(SIPI).
    L0 trap LAPIC.ICR write(INIT): inject a latched SIPI event to traget
       vCPU.
Target vCPU:
    L0 emulate an SIPI VMExit to L1 if (vcpu.mp_state == INIT_RECEIVED).
    L1 set CS:IP, guest_activity_state=ACTIVE, vmresume.
    L0 resume to L2.
    L2 start-up.

Signed-off-by: Yadong Qi <yadong.qi@intel.com>
Message-Id: <20200922052343.84388-1-yadong.qi@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20201106065122.403183-1-yadong.qi@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Yadong Qi
2020-11-06 14:51:22 +08:00
committed by Paolo Bonzini
parent 1c96dcceae
commit bf0cd88ce3
3 changed files with 44 additions and 14 deletions
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2
arch/x86/include/uapi/asm/vmx.h
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@@ -32,6 +32,7 @@
#define EXIT_REASON_EXTERNAL_INTERRUPT 1
#define EXIT_REASON_TRIPLE_FAULT 2
#define EXIT_REASON_INIT_SIGNAL 3
#define EXIT_REASON_SIPI_SIGNAL 4
#define EXIT_REASON_INTERRUPT_WINDOW 7
#define EXIT_REASON_NMI_WINDOW 8
@@ -94,6 +95,7 @@
{ EXIT_REASON_EXTERNAL_INTERRUPT, "EXTERNAL_INTERRUPT" }, \
{ EXIT_REASON_TRIPLE_FAULT, "TRIPLE_FAULT" }, \
{ EXIT_REASON_INIT_SIGNAL, "INIT_SIGNAL" }, \
{ EXIT_REASON_SIPI_SIGNAL, "SIPI_SIGNAL" }, \
{ EXIT_REASON_INTERRUPT_WINDOW, "INTERRUPT_WINDOW" }, \
{ EXIT_REASON_NMI_WINDOW, "NMI_WINDOW" }, \
{ EXIT_REASON_TASK_SWITCH, "TASK_SWITCH" }, \