File 5ddfa851-VMX-always-sync-PIR-to-IRR.patch of Package xen.13549

# Commit 56348df32bbc782e63b6e3fb978b80e015ae76e7
# Date 2019-11-28 11:58:25 +0100
# Author Roger Pau Monné <roger.pau@citrix.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86/vmx: always sync PIR to IRR before vmentry

When using posted interrupts on Intel hardware it's possible that the
vCPU resumes execution with a stale local APIC IRR register because
depending on the interrupts to be injected vlapic_has_pending_irq
might not be called, and thus PIR won't be synced into IRR.

Fix this by making sure PIR is always synced to IRR in
hvm_vcpu_has_pending_irq regardless of what interrupts are pending.

Reported-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Joe Jin <joe.jin@oracle.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/hvm/irq.c
+++ b/xen/arch/x86/hvm/irq.c
@@ -517,6 +517,15 @@ struct hvm_intack hvm_vcpu_has_pending_i
     struct hvm_domain *plat = &v->domain->arch.hvm;
     int vector;
 
+    /*
+     * Always call vlapic_sync_pir_to_irr so that PIR is synced into IRR when
+     * using posted interrupts. Note this is also done by
+     * vlapic_has_pending_irq but depending on which interrupts are pending
+     * hvm_vcpu_has_pending_irq will return early without calling
+     * vlapic_has_pending_irq.
+     */
+    vlapic_sync_pir_to_irr(v);
+
     if ( unlikely(v->nmi_pending) )
         return hvm_intack_nmi;
 
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -113,8 +113,7 @@ static void vlapic_clear_irr(int vector,
 
 static int vlapic_find_highest_irr(struct vlapic *vlapic)
 {
-    if ( hvm_funcs.sync_pir_to_irr )
-        hvm_funcs.sync_pir_to_irr(vlapic_vcpu(vlapic));
+    vlapic_sync_pir_to_irr(vlapic_vcpu(vlapic));
 
     return vlapic_find_highest_vector(&vlapic->regs->data[APIC_IRR]);
 }
@@ -1472,8 +1471,7 @@ static int lapic_save_regs(struct vcpu *
     if ( !has_vlapic(v->domain) )
         return 0;
 
-    if ( hvm_funcs.sync_pir_to_irr )
-        hvm_funcs.sync_pir_to_irr(v);
+    vlapic_sync_pir_to_irr(v);
 
     return hvm_save_entry(LAPIC_REGS, v->vcpu_id, h, vcpu_vlapic(v)->regs);
 }
--- a/xen/include/asm-x86/hvm/vlapic.h
+++ b/xen/include/asm-x86/hvm/vlapic.h
@@ -150,4 +150,10 @@ bool_t vlapic_match_dest(
     const struct vlapic *target, const struct vlapic *source,
     int short_hand, uint32_t dest, bool_t dest_mode);
 
+static inline void vlapic_sync_pir_to_irr(struct vcpu *v)
+{
+    if ( hvm_funcs.sync_pir_to_irr )
+        hvm_funcs.sync_pir_to_irr(v);
+}
+
 #endif /* __ASM_X86_HVM_VLAPIC_H__ */