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authorRadim Krčmář <rkrcmar@redhat.com>2016-07-12 23:09:27 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2016-07-14 10:03:57 +0300
commit3713131345fbea291cbd859d248e06ed77815962 (patch)
treefb712d5c0b49b53984a3b01d0df29c7dfee62e4e /arch/x86/kvm/lapic.c
parentc63cf538eb4bf6a5ffd3750366d8d56f023645a5 (diff)
downloadlinux-3713131345fbea291cbd859d248e06ed77815962.tar.xz
KVM: x86: add KVM_CAP_X2APIC_API
KVM_CAP_X2APIC_API is a capability for features related to x2APIC enablement. KVM_X2APIC_API_32BIT_FORMAT feature can be enabled to extend APIC ID in get/set ioctl and MSI addresses to 32 bits. Both are needed to support x2APIC. The feature has to be enableable and disabled by default, because get/set ioctl shifted and truncated APIC ID to 8 bits by using a non-standard protocol inspired by xAPIC and the change is not backward-compatible. Changes to MSI addresses follow the format used by interrupt remapping unit. The upper address word, that used to be 0, contains upper 24 bits of the LAPIC address in its upper 24 bits. Lower 8 bits are reserved as 0. Using the upper address word is not backward-compatible either as we didn't check that userspace zeroed the word. Reserved bits are still not explicitly checked, but non-zero data will affect LAPIC addresses, which will cause a bug. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/lapic.c')
-rw-r--r--arch/x86/kvm/lapic.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 3c2a8c113054..d27a7829a4ce 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1991,10 +1991,15 @@ static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
if (apic_x2apic_mode(vcpu->arch.apic)) {
u32 *id = (u32 *)(s->regs + APIC_ID);
- if (set)
- *id >>= 24;
- else
- *id <<= 24;
+ if (vcpu->kvm->arch.x2apic_format) {
+ if (*id != vcpu->vcpu_id)
+ return -EINVAL;
+ } else {
+ if (set)
+ *id >>= 24;
+ else
+ *id <<= 24;
+ }
}
return 0;