[Xen-changelog] [xen stable-4.11] x86/vmx: always sync PIR to IRR before vmentry

[patchbot@xxxxxxx]

commit d397a5a31aec25b1e9242486930ddf7bed149865
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Wed Dec 11 15:27:17 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Dec 11 15:27:17 2019 +0100

    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@xxxxxxxxxx>
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Tested-by: Joe Jin <joe.jin@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 56348df32bbc782e63b6e3fb978b80e015ae76e7
    master date: 2019-11-28 11:58:25 +0100
---
 xen/arch/x86/hvm/irq.c           | 9 +++++++++
 xen/arch/x86/hvm/vlapic.c        | 6 ++----
 xen/include/asm-x86/hvm/vlapic.h | 6 ++++++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/irq.c b/xen/arch/x86/hvm/irq.c
index 2b7d8edb96..c8b310e92c 100644
--- a/xen/arch/x86/hvm/irq.c
+++ b/xen/arch/x86/hvm/irq.c
@@ -497,6 +497,15 @@ struct hvm_intack hvm_vcpu_has_pending_irq(struct vcpu *v)
     struct hvm_domain *plat = &v->domain->arch.hvm_domain;
     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;
 
diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 871c9a46b4..85601c8c2d 100644
--- 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, struct vlapic 
*vlapic)
 
 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]);
 }
@@ -1438,8 +1437,7 @@ static int lapic_save_regs(struct domain *d, 
hvm_domain_context_t *h)
 
     for_each_vcpu ( d, v )
     {
-        if ( hvm_funcs.sync_pir_to_irr )
-            hvm_funcs.sync_pir_to_irr(v);
+        vlapic_sync_pir_to_irr(v);
 
         s = vcpu_vlapic(v);
         if ( (rc = hvm_save_entry(LAPIC_REGS, v->vcpu_id, h, s->regs)) != 0 )
diff --git a/xen/include/asm-x86/hvm/vlapic.h b/xen/include/asm-x86/hvm/vlapic.h
index 212c36b5c2..ab296dfe99 100644
--- a/xen/include/asm-x86/hvm/vlapic.h
+++ b/xen/include/asm-x86/hvm/vlapic.h
@@ -145,4 +145,10 @@ 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__ */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.11

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