Re: [PATCH hyperv-next v4 03/16] arch: hyperv: Get/set SynIC synth.registers via paravisor

[kernel test robot <lkp@intel.com>]

Hi Roman,

kernel test robot noticed the following build errors:

[auto build test ERROR on d9016a249be5316ec2476f9947356711e70a16ec]

url:    https://github.com/intel-lab-lkp/linux/commits/Roman-Kisel/Documentation-hyperv-Confidential-VMBus/20250715-062125
base:   d9016a249be5316ec2476f9947356711e70a16ec
patch link:    https://lore.kernel.org/r/20250714221545.5615-4-romank%40linux.microsoft.com
patch subject: [PATCH hyperv-next v4 03/16] arch: hyperv: Get/set SynIC synth.registers via paravisor
config: i386-buildonly-randconfig-005-20250715 (https://download.01.org/0day-ci/archive/20250715/202507152017.8UNXIbRJ-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250715/202507152017.8UNXIbRJ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507152017.8UNXIbRJ-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/x86/kvm/vmx/main.c:5:
   In file included from arch/x86/kvm/vmx/vmx.h:16:
   In file included from arch/x86/kvm/vmx/vmx_ops.h:9:
   In file included from arch/x86/kvm/vmx/vmx_onhyperv.h:7:
   In file included from arch/x86/include/asm/mshyperv.h:345:
>> include/asm-generic/mshyperv.h:377:4: error: call to undeclared function 'hv_para_set_synic_register'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     377 |                         hv_para_set_synic_register(HV_MSR_EOM, 0);
         |                         ^
   1 error generated.
--
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:9:
   In file included from arch/x86/include/asm/mshyperv.h:345:
>> include/asm-generic/mshyperv.h:377:4: error: call to undeclared function 'hv_para_set_synic_register'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     377 |                         hv_para_set_synic_register(HV_MSR_EOM, 0);
         |                         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:98:11: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
      98 |                 return (set->sig[3] | set->sig[2] |
         |                         ^        ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:98:25: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
      98 |                 return (set->sig[3] | set->sig[2] |
         |                                       ^        ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:114:11: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     114 |                 return  (set1->sig[3] == set2->sig[3]) &&
         |                          ^         ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:114:27: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     114 |                 return  (set1->sig[3] == set2->sig[3]) &&
         |                                          ^         ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:115:5: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     115 |                         (set1->sig[2] == set2->sig[2]) &&
         |                          ^         ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:115:21: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     115 |                         (set1->sig[2] == set2->sig[2]) &&
         |                                          ^         ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:157:1: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     157 | _SIG_SET_BINOP(sigorsets, _sig_or)
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/signal.h:138:8: note: expanded from macro '_SIG_SET_BINOP'
     138 |                 a3 = a->sig[3]; a2 = a->sig[2];                         \
         |                      ^      ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:157:1: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     157 | _SIG_SET_BINOP(sigorsets, _sig_or)
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/signal.h:138:24: note: expanded from macro '_SIG_SET_BINOP'
     138 |                 a3 = a->sig[3]; a2 = a->sig[2];                         \
         |                                      ^      ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];
         |         ^
   In file included from arch/x86/kvm/svm/hyperv.c:7:
   In file included from arch/x86/kvm/svm/hyperv.h:11:
   In file included from arch/x86/kvm/svm/../hyperv.h:24:
   In file included from include/linux/kvm_host.h:11:
   include/linux/signal.h:157:1: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
     157 | _SIG_SET_BINOP(sigorsets, _sig_or)
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/signal.h:139:8: note: expanded from macro '_SIG_SET_BINOP'
     139 |                 b3 = b->sig[3]; b2 = b->sig[2];                         \
         |                      ^      ~
   arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
      24 |         unsigned long sig[_NSIG_WORDS];


vim +/hv_para_set_synic_register +377 include/asm-generic/mshyperv.h

   344	
   345	/* Free the message slot and signal end-of-message if required */
   346	static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
   347	{
   348		/*
   349		 * On crash we're reading some other CPU's message page and we need
   350		 * to be careful: this other CPU may already had cleared the header
   351		 * and the host may already had delivered some other message there.
   352		 * In case we blindly write msg->header.message_type we're going
   353		 * to lose it. We can still lose a message of the same type but
   354		 * we count on the fact that there can only be one
   355		 * CHANNELMSG_UNLOAD_RESPONSE and we don't care about other messages
   356		 * on crash.
   357		 */
   358		if (cmpxchg(&msg->header.message_type, old_msg_type,
   359			    HVMSG_NONE) != old_msg_type)
   360			return;
   361	
   362		/*
   363		 * The cmxchg() above does an implicit memory barrier to
   364		 * ensure the write to MessageType (ie set to
   365		 * HVMSG_NONE) happens before we read the
   366		 * MessagePending and EOMing. Otherwise, the EOMing
   367		 * will not deliver any more messages since there is
   368		 * no empty slot
   369		 */
   370		if (msg->header.message_flags.msg_pending) {
   371			/*
   372			 * This will cause message queue rescan to
   373			 * possibly deliver another msg from the
   374			 * hypervisor
   375			 */
   376			if (vmbus_is_confidential())
 > 377				hv_para_set_synic_register(HV_MSR_EOM, 0);
   378			else
   379				hv_set_msr(HV_MSR_EOM, 0);
   380		}
   381	}
   382	

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