[Xen-changelog] [xen stable-4.12] x86/vmx: always sync PIR to IRR before vmentry

[patchbot@xxxxxxx]

commit dde68d8e3fadf9b50c96b63634d98c5c3fe375b0
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Fri Dec 6 12:42:13 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 6 12:42:13 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 e03a87ad50..c684422b24 100644
--- 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_irq(struct vcpu *v)
     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;
 
diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index d652c5fb20..f12fe976cd 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]);
 }
@@ -1472,8 +1471,7 @@ static int lapic_save_regs(struct vcpu *v, 
hvm_domain_context_t *h)
     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);
 }
diff --git a/xen/include/asm-x86/hvm/vlapic.h b/xen/include/asm-x86/hvm/vlapic.h
index dde66b4f0f..c1a252b9d5 100644
--- 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__ */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12

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