WARN if the save state size for a valid XCR0-managed sub-leaf is zero,
which would indicate a KVM or CPU bug. Add a comment to explain why KVM
WARNs so the reader doesn't have to tease out the relevant bits from
Intel's SDM and KVM's XCR0/XSS code.
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
goto out;
do_host_cpuid(&entry[i], function, idx);
- if (entry[i].eax == 0)
- continue;
- if (WARN_ON_ONCE(entry[i].ecx & 1))
+
+ /*
+ * The @supported check above should have filtered out
+ * invalid sub-leafs as well as sub-leafs managed by
+ * IA32_XSS MSR. Only XCR0-managed sub-leafs should
+ * reach this point, and they should have a non-zero
+ * save state size.
+ */
+ if (WARN_ON_ONCE(!entry[i].eax || (entry[i].ecx & 1)))
continue;
+
entry[i].ecx = 0;
entry[i].edx = 0;
++*nent;