[Xen-devel] [PATCH for-4.13] x86/vlapic: allow setting APIC_SPIV_FOCUS_DISABLED in x2APIC mode

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

Current code unconditionally prevents setting APIC_SPIV_FOCUS_DISABLED
regardless of the processor model, which is not correct according to
the specification.

Fix it by allowing setting APIC_SPIV_FOCUS_DISABLED based on the
domain cpuid policy.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Juergen Gross <jgross@xxxxxxxx>
---
 xen/arch/x86/hvm/vlapic.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 9466258d6f..b318b4ed5c 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -977,6 +977,7 @@ int guest_wrmsr_x2apic(struct vcpu *v, uint32_t msr, 
uint64_t msr_content)
 {
     struct vlapic *vlapic = vcpu_vlapic(v);
     uint32_t offset = (msr - MSR_X2APIC_FIRST) << 4;
+    const struct cpuid_policy *cpuid = v->domain->arch.cpuid;
 
     /* The timer handling at least is unsafe outside of current context. */
     ASSERT(v == current);
@@ -993,6 +994,14 @@ int guest_wrmsr_x2apic(struct vcpu *v, uint32_t msr, 
uint64_t msr_content)
 
     case APIC_SPIV:
         if ( msr_content & ~(APIC_VECTOR_MASK | APIC_SPIV_APIC_ENABLED |
+                             /*
+                              * APIC_SPIV_FOCUS_DISABLED is not supported on
+                              * Intel Pentium 4 and Xeon processors.
+                              */
+                             ((cpuid->x86_vendor != X86_VENDOR_INTEL ||
+                               get_cpu_family(cpuid->basic.raw_fms, NULL,
+                                              NULL) != 15) ?
+                               APIC_SPIV_FOCUS_DISABLED : 0) |
                              (VLAPIC_VERSION & APIC_LVR_DIRECTED_EOI
                               ? APIC_SPIV_DIRECTED_EOI : 0)) )
             return X86EMUL_EXCEPTION;
-- 
2.24.0


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