[tglx-devel:rseq/perf 17/47] drivers/hv/mshv_root_main.c:588:2: error: call to undeclared function 'rseq_virt_userspace_exit'; ISO C99 and later do not support implicit function declarations

[tglx-devel:rseq/perf 17/47] drivers/hv/mshv_root_main.c:588:2: error: call to undeclared function 'rseq_virt_userspace_exit'; ISO C99 and later do not support implicit function declarations

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git rseq/perf
head:   eb43860d07d75ca9e20e5716da7f8dddee478ed9
commit: 0de985a3d3f07cb83e1bb418183c75579c3fd912 [17/47] rseq, virt: Retrigger RSEQ after vcpu_run()
config: x86_64-randconfig-161-20250824 (https://download.01.org/0day-ci/archive/20250824/202508241053.wbAfNuDn-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/20250824/202508241053.wbAfNuDn-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/202508241053.wbAfNuDn-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/hv/mshv_root_main.c:588:2: error: call to undeclared function 'rseq_virt_userspace_exit'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     588 |         rseq_virt_userspace_exit();
         |         ^
   1 error generated.


vim +/rseq_virt_userspace_exit +588 drivers/hv/mshv_root_main.c

   511	
   512	/* Must be called with interrupts enabled */
   513	static long mshv_run_vp_with_root_scheduler(struct mshv_vp *vp)
   514	{
   515		long ret;
   516	
   517		if (vp->run.flags.root_sched_blocked) {
   518			/*
   519			 * Dispatch state of this VP is blocked. Need to wait
   520			 * for the hypervisor to clear the blocked state before
   521			 * dispatching it.
   522			 */
   523			ret = mshv_vp_wait_for_hv_kick(vp);
   524			if (ret)
   525				return ret;
   526		}
   527	
   528		do {
   529			u32 flags = 0;
   530			struct hv_output_dispatch_vp output;
   531	
   532			ret = mshv_pre_guest_mode_work(vp);
   533			if (ret)
   534				break;
   535	
   536			if (vp->run.flags.intercept_suspend)
   537				flags |= HV_DISPATCH_VP_FLAG_CLEAR_INTERCEPT_SUSPEND;
   538	
   539			if (mshv_vp_interrupt_pending(vp))
   540				flags |= HV_DISPATCH_VP_FLAG_SCAN_INTERRUPT_INJECTION;
   541	
   542			ret = mshv_vp_dispatch(vp, flags, &output);
   543			if (ret)
   544				break;
   545	
   546			vp->run.flags.intercept_suspend = 0;
   547	
   548			if (output.dispatch_state == HV_VP_DISPATCH_STATE_BLOCKED) {
   549				if (output.dispatch_event ==
   550							HV_VP_DISPATCH_EVENT_SUSPEND) {
   551					/*
   552					 * TODO: remove the warning once VP canceling
   553					 *	 is supported
   554					 */
   555					WARN_ONCE(atomic64_read(&vp->run.vp_signaled_count),
   556						  "%s: vp#%d: unexpected explicit suspend\n",
   557						  __func__, vp->vp_index);
   558					/*
   559					 * Need to clear explicit suspend before
   560					 * dispatching.
   561					 * Explicit suspend is either:
   562					 * - set right after the first VP dispatch or
   563					 * - set explicitly via hypercall
   564					 * Since the latter case is not yet supported,
   565					 * simply clear it here.
   566					 */
   567					ret = mshv_vp_clear_explicit_suspend(vp);
   568					if (ret)
   569						break;
   570	
   571					ret = mshv_vp_wait_for_hv_kick(vp);
   572					if (ret)
   573						break;
   574				} else {
   575					vp->run.flags.root_sched_blocked = 1;
   576					ret = mshv_vp_wait_for_hv_kick(vp);
   577					if (ret)
   578						break;
   579				}
   580			} else {
   581				/* HV_VP_DISPATCH_STATE_READY */
   582				if (output.dispatch_event ==
   583							HV_VP_DISPATCH_EVENT_INTERCEPT)
   584					vp->run.flags.intercept_suspend = 1;
   585			}
   586		} while (!vp->run.flags.intercept_suspend);
   587	
 > 588		rseq_virt_userspace_exit();
   589	
   590		return ret;
   591	}
   592	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [tglx-devel:rseq/perf 17/47] drivers/hv/mshv_root_main.c:588:2: error: call to undeclared function 'rseq_virt_userspace_exit'; ISO C99 and later do not support implicit function declarations

[Thomas Gleixner]

On Sun, Aug 24 2025 at 10:25, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git rseq/perf
> head:   eb43860d07d75ca9e20e5716da7f8dddee478ed9
> commit: 0de985a3d3f07cb83e1bb418183c75579c3fd912 [17/47] rseq, virt: Retrigger RSEQ after vcpu_run()
> config: x86_64-randconfig-161-20250824 (https://download.01.org/0day-ci/archive/20250824/202508241053.wbAfNuDn-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/20250824/202508241053.wbAfNuDn-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/202508241053.wbAfNuDn-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
>>> drivers/hv/mshv_root_main.c:588:2: error: call to undeclared function 'rseq_virt_userspace_exit'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
>      588 |         rseq_virt_userspace_exit();
>          |         ^

Bah. lacks an include...