[Xen-devel] [PATCH v2 2/4] x86/vvmx: fix VM_EXIT_ACK_INTR_ON_EXIT handling

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

When VM_EXIT_ACK_INTR_ON_EXIT is set in the vmexit control vmcs
register the bit 31 of VM_EXIT_INTR_INFO must be 0, in order to denote
that the field doesn't contain any interrupt information. This is not
currently acknowledged as the field always get filled with valid
interrupt information, regardless of whether VM_EXIT_ACK_INTR_ON_EXIT
is set.

Fix this and only fill VM_EXIT_INTR_INFO when VM_EXIT_ACK_INTR_ON_EXIT
is not set. Note that this requires one minor change in
nvmx_update_apicv in order to obtain the interrupt information from
the internal state rather than the nested vmcs register.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Changes since v1:
 - New in this version.
---
 xen/arch/x86/hvm/vmx/vvmx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 3d97a293b2..47eee1e5b9 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -1283,6 +1283,7 @@ static void load_vvmcs_host_state(struct vcpu *v)
 static void sync_exception_state(struct vcpu *v)
 {
     struct nestedvmx *nvmx = &vcpu_2_nvmx(v);
+    uint32_t exit_ctrl = get_vvmcs(v, VM_EXIT_CONTROLS);
 
     if ( !(nvmx->intr.intr_info & INTR_INFO_VALID_MASK) )
         return;
@@ -1294,7 +1295,8 @@ static void sync_exception_state(struct vcpu *v)
         set_vvmcs(v, VM_EXIT_REASON, EXIT_REASON_EXTERNAL_INTERRUPT);
         set_vvmcs(v, EXIT_QUALIFICATION, 0);
         set_vvmcs(v, VM_EXIT_INTR_INFO,
-                    nvmx->intr.intr_info);
+                  (exit_ctrl & VM_EXIT_ACK_INTR_ON_EXIT) ? nvmx->intr.intr_info
+                                                         : 0);
         break;
 
     case X86_EVENTTYPE_HW_EXCEPTION:
@@ -1320,7 +1322,7 @@ static void nvmx_update_apicv(struct vcpu *v)
 {
     struct nestedvmx *nvmx = &vcpu_2_nvmx(v);
     unsigned long reason = get_vvmcs(v, VM_EXIT_REASON);
-    uint32_t intr_info = get_vvmcs(v, VM_EXIT_INTR_INFO);
+    uint32_t intr_info = nvmx->intr.intr_info;
 
     if ( reason == EXIT_REASON_EXTERNAL_INTERRUPT &&
          nvmx->intr.source == hvm_intsrc_lapic &&
-- 
2.25.0


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