[Xen-devel] [PATCH] x86/levelling: Avoid NULL pointer dereference

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Coverity points out that next is indeed NULL at times.  Only try to read the
.cpuid_faulting field when we sure that next isn't NULL.

Fixes e7a370733bd "x86: replace arch_vcpu::cpuid_faulting with msr_vcpu_policy"

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
---
 xen/arch/x86/cpu/intel.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/xen/arch/x86/cpu/intel.c b/xen/arch/x86/cpu/intel.c
index 218236d..ac932e5 100644
--- a/xen/arch/x86/cpu/intel.c
+++ b/xen/arch/x86/cpu/intel.c
@@ -156,7 +156,6 @@ static void intel_ctxt_switch_levelling(const struct vcpu 
*next)
        struct cpuidmasks *these_masks = &this_cpu(cpuidmasks);
        const struct domain *nextd = next ? next->domain : NULL;
        const struct cpuidmasks *masks;
-       const struct msr_vcpu_policy *vp = next->arch.msr;
 
        if (cpu_has_cpuid_faulting) {
                /*
@@ -177,7 +176,7 @@ static void intel_ctxt_switch_levelling(const struct vcpu 
*next)
                 */
                set_cpuid_faulting(nextd && !is_control_domain(nextd) &&
                                   (is_pv_domain(nextd) ||
-                                   vp->misc_features_enables.cpuid_faulting));
+                                   
next->arch.msr->misc_features_enables.cpuid_faulting));
                return;
        }
 
-- 
2.1.4


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