KVM: x86: Rework INIT and SIPI handling

A VCPU sending INIT or SIPI to some other VCPU races for setting the
remote VCPU's mp_state. When we were unlucky, KVM_MP_STATE_INIT_RECEIVED
was overwritten by kvm_emulate_halt and, thus, got lost.

This introduces APIC events for those two signals, keeping them in
kvm_apic until kvm_apic_accept_events is run over the target vcpu
context. kvm_apic_has_events reports to kvm_arch_vcpu_runnable if there
are pending events, thus if vcpu blocking should end.

The patch comes with the side effect of effectively obsoleting
KVM_MP_STATE_SIPI_RECEIVED. We still accept it from user space, but
immediately translate it to KVM_MP_STATE_INIT_RECEIVED + KVM_APIC_SIPI.
The vcpu itself will no longer enter the KVM_MP_STATE_SIPI_RECEIVED
state. That also means we no longer exit to user space after receiving a
SIPI event.

Furthermore, we already reset the VCPU on INIT, only fixing up the code
segment later on when SIPI arrives. Moreover, we fix INIT handling for
the BSP: it never enter wait-for-SIPI but directly starts over on INIT.

Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

1 files changed, 2 insertions, 10 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f588171be177..af1ffaf20892 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4119,12 +4119,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
         vmx_segment_cache_clear(vmx);
 
         seg_setup(VCPU_SREG_CS);
-        if (kvm_vcpu_is_bsp(&vmx->vcpu))
-                vmcs_write16(GUEST_CS_SELECTOR, 0xf000);
-        else {
-                vmcs_write16(GUEST_CS_SELECTOR, vmx->vcpu.arch.sipi_vector << 8);
-                vmcs_writel(GUEST_CS_BASE, vmx->vcpu.arch.sipi_vector << 12);
-        }
+        vmcs_write16(GUEST_CS_SELECTOR, 0xf000);
 
         seg_setup(VCPU_SREG_DS);
         seg_setup(VCPU_SREG_ES);
@@ -4147,10 +4142,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
         vmcs_writel(GUEST_SYSENTER_EIP, 0);
 
         vmcs_writel(GUEST_RFLAGS, 0x02);
-        if (kvm_vcpu_is_bsp(&vmx->vcpu))
-                kvm_rip_write(vcpu, 0xfff0);
-        else
-                kvm_rip_write(vcpu, 0);
+        kvm_rip_write(vcpu, 0xfff0);
 
         vmcs_writel(GUEST_GDTR_BASE, 0);
         vmcs_write32(GUEST_GDTR_LIMIT, 0xffff);