[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] x86/HVM: don't mark evtchn upcall vector as pending when vLAPIC is disabled
commit f5d0279839b58cb622f0995dbf9cff056f03082e Author: Jan Beulich <jbeulich@xxxxxxxx> AuthorDate: Tue Dec 6 13:51:49 2022 +0100 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Tue Dec 6 13:51:49 2022 +0100 x86/HVM: don't mark evtchn upcall vector as pending when vLAPIC is disabled Linux'es relatively new use of HVMOP_set_evtchn_upcall_vector has exposed a problem with the marking of the respective vector as pending: For quite some time Linux has been checking whether any stale ISR or IRR bits would still be set while preparing the LAPIC for use. This check is now triggering on the upcall vector, as the registration, at least for APs, happens before the LAPIC is actually enabled. In software-disabled state an LAPIC would not accept any interrupt requests and hence no IRR bit would newly become set while in this state. As a result it is also wrong for us to mark the upcall vector as having a pending request when the vLAPIC is in this state. To compensate for the "enabled" check added to the assertion logic, add logic to (conditionally) mark the upcall vector as having a request pending at the time the LAPIC is being software-enabled by the guest. Note however that, like for the pt_may_unmask_irq() we already have there, long term we may need to find a different solution. This will be especially relevant in case yet better LAPIC acceleration would eliminate notifications of guest writes to this and other registers. Fixes: 7b5b8ca7dffd ("x86/upcall: inject a spurious event after setting upcall vector") Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Juergen Gross <jgross@xxxxxxxx> --- xen/arch/x86/hvm/irq.c | 5 +++-- xen/arch/x86/hvm/vlapic.c | 3 +++ 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/hvm/irq.c b/xen/arch/x86/hvm/irq.c index 858ab5b248..d93ffe4546 100644 --- a/xen/arch/x86/hvm/irq.c +++ b/xen/arch/x86/hvm/irq.c @@ -321,9 +321,10 @@ void hvm_assert_evtchn_irq(struct vcpu *v) if ( v->arch.hvm.evtchn_upcall_vector != 0 ) { - uint8_t vector = v->arch.hvm.evtchn_upcall_vector; + struct vlapic *vlapic = vcpu_vlapic(v); - vlapic_set_irq(vcpu_vlapic(v), vector, 0); + if ( vlapic_enabled(vlapic) ) + vlapic_set_irq(vlapic, v->arch.hvm.evtchn_upcall_vector, 0); } else if ( is_hvm_pv_evtchn_domain(v->domain) ) vcpu_kick(v); diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c index 257d3b6851..eb32f12e2d 100644 --- a/xen/arch/x86/hvm/vlapic.c +++ b/xen/arch/x86/hvm/vlapic.c @@ -829,6 +829,9 @@ void vlapic_reg_write(struct vcpu *v, unsigned int reg, uint32_t val) { vlapic->hw.disabled &= ~VLAPIC_SW_DISABLED; pt_may_unmask_irq(vlapic_domain(vlapic), &vlapic->pt); + if ( v->arch.hvm.evtchn_upcall_vector && + vcpu_info(v, evtchn_upcall_pending) ) + vlapic_set_irq(vlapic, v->arch.hvm.evtchn_upcall_vector, 0); } break; -- generated by git-patchbot for /home/xen/git/xen.git#master
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