diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2020-12-09 23:08:30 +0300 |
|---|---|---|
| committer | David Woodhouse <dwmw@amazon.co.uk> | 2021-02-04 17:19:39 +0300 |
| commit | 40da8ccd724f7ca2f08550a46268bc3a91cc8869 (patch) | |
| tree | 7f9240ecbda4aa6a5b33cd2b75d408aed68df5d9 /arch/x86/kvm/irq.c | |
| parent | f2340cd9e41dc463cb1189274f3db560c1dfa1f4 (diff) | |
| download | linux-40da8ccd724f7ca2f08550a46268bc3a91cc8869.tar.xz | |
KVM: x86/xen: Add event channel interrupt vector upcall
It turns out that we can't handle event channels *entirely* in userspace
by delivering them as ExtINT, because KVM is a bit picky about when it
accepts ExtINT interrupts from a legacy PIC. The in-kernel local APIC
has to have LVT0 configured in APIC_MODE_EXTINT and unmasked, which
isn't necessarily the case for Xen guests especially on secondary CPUs.
To cope with this, add kvm_xen_get_interrupt() which checks the
evtchn_pending_upcall field in the Xen vcpu_info, and delivers the Xen
upcall vector (configured by KVM_XEN_ATTR_TYPE_UPCALL_VECTOR) if it's
set regardless of LAPIC LVT0 configuration. This gives us the minimum
support we need for completely userspace-based implementation of event
channels.
This does mean that vcpu_enter_guest() needs to check for the
evtchn_pending_upcall flag being set, because it can't rely on someone
having set KVM_REQ_EVENT unless we were to add some way for userspace to
do so manually.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Diffstat (limited to 'arch/x86/kvm/irq.c')
| -rw-r--r-- | arch/x86/kvm/irq.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c index a035cca82f8f..172b05343cfd 100644 --- a/arch/x86/kvm/irq.c +++ b/arch/x86/kvm/irq.c @@ -14,6 +14,7 @@ #include "irq.h" #include "i8254.h" #include "x86.h" +#include "xen.h" /* * check if there are pending timer events @@ -56,6 +57,9 @@ int kvm_cpu_has_extint(struct kvm_vcpu *v) if (!lapic_in_kernel(v)) return v->arch.interrupt.injected; + if (kvm_xen_has_interrupt(v)) + return 1; + if (!kvm_apic_accept_pic_intr(v)) return 0; @@ -110,6 +114,9 @@ static int kvm_cpu_get_extint(struct kvm_vcpu *v) if (!lapic_in_kernel(v)) return v->arch.interrupt.nr; + if (kvm_xen_has_interrupt(v)) + return v->kvm->arch.xen.upcall_vector; + if (irqchip_split(v->kvm)) { int vector = v->arch.pending_external_vector; |