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Date:   Sat, 1 Oct 2022 21:10:47 +0800
From:   kernel test robot <lkp@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     kbuild-all@...ts.01.org, seanjc@...gle.com,
        maciej.szmigiero@...cle.com
Subject: Re: [PATCH v2 4/8] KVM: x86: do not go through ctxt->ops when
 emulating rsm

Hi Paolo,

I love your patch! Perhaps something to improve:

[auto build test WARNING on kvm/queue]
[also build test WARNING on next-20220930]
[cannot apply to mst-vhost/linux-next linus/master v6.0-rc7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Paolo-Bonzini/KVM-x86-allow-compiling-out-SMM-support/20220930-012220
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
config: i386-randconfig-a001-20220926
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/cc73a769dae68cad03e5f075d8b09aac79cd0125
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Paolo-Bonzini/KVM-x86-allow-compiling-out-SMM-support/20220930-012220
        git checkout cc73a769dae68cad03e5f075d8b09aac79cd0125
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kvm/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   arch/x86/kvm/smm.c: In function 'emulator_leave_smm':
>> arch/x86/kvm/smm.c:503:33: warning: unused variable 'efer' [-Wunused-variable]
     503 |         unsigned long cr0, cr4, efer;
         |                                 ^~~~
>> arch/x86/kvm/smm.c:503:28: warning: unused variable 'cr4' [-Wunused-variable]
     503 |         unsigned long cr0, cr4, efer;
         |                            ^~~


vim +/efer +503 arch/x86/kvm/smm.c

cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  499  
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  500  int emulator_leave_smm(struct x86_emulate_ctxt *ctxt)
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  501  {
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  502  	struct kvm_vcpu *vcpu = ctxt->vcpu;
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29 @503  	unsigned long cr0, cr4, efer;
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  504  	char buf[512];
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  505  	u64 smbase;
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  506  	int ret;
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  507  
cc73a769dae68c Paolo Bonzini 2022-09-29  508  	smbase = vcpu->arch.smbase;
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  509  
cc73a769dae68c Paolo Bonzini 2022-09-29  510  	ret = kvm_vcpu_read_guest(vcpu, smbase + 0xfe00, buf, sizeof(buf));
cc73a769dae68c Paolo Bonzini 2022-09-29  511  	if (ret < 0)
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  512  		return X86EMUL_UNHANDLEABLE;
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  513  
cc73a769dae68c Paolo Bonzini 2022-09-29  514  	if ((vcpu->arch.hflags & HF_SMM_INSIDE_NMI_MASK) == 0)
cc73a769dae68c Paolo Bonzini 2022-09-29  515  		static_call(kvm_x86_set_nmi_mask)(vcpu, false);
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  516  
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  517  	kvm_smm_changed(vcpu, false);
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  518  
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  519  	/*
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  520  	 * Get back to real mode, to prepare a safe state in which to load
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  521  	 * CR0/CR3/CR4/EFER.  It's all a bit more complicated if the vCPU
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  522  	 * supports long mode.
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  523  	 */
cc73a769dae68c Paolo Bonzini 2022-09-29  524  #ifdef CONFIG_X86_64
cc73a769dae68c Paolo Bonzini 2022-09-29  525  	if (guest_cpuid_has(vcpu, X86_FEATURE_LM)) {
cc73a769dae68c Paolo Bonzini 2022-09-29  526  		struct kvm_segment cs_desc;
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  527  
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  528  		/* Zero CR4.PCIDE before CR0.PG.  */
cc73a769dae68c Paolo Bonzini 2022-09-29  529  		cr4 = kvm_read_cr4(vcpu);
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  530  		if (cr4 & X86_CR4_PCIDE)
cc73a769dae68c Paolo Bonzini 2022-09-29  531  			kvm_set_cr4(vcpu, cr4 & ~X86_CR4_PCIDE);
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  532  
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  533  		/* A 32-bit code segment is required to clear EFER.LMA.  */
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  534  		memset(&cs_desc, 0, sizeof(cs_desc));
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  535  		cs_desc.type = 0xb;
cc73a769dae68c Paolo Bonzini 2022-09-29  536  		cs_desc.s = cs_desc.g = cs_desc.present = 1;
cc73a769dae68c Paolo Bonzini 2022-09-29  537  		kvm_set_segment(vcpu, &cs_desc, VCPU_SREG_CS);
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  538  	}
cc73a769dae68c Paolo Bonzini 2022-09-29  539  #endif
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  540  
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  541  	/* For the 64-bit case, this will clear EFER.LMA.  */
cc73a769dae68c Paolo Bonzini 2022-09-29  542  	cr0 = kvm_read_cr0(vcpu);
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  543  	if (cr0 & X86_CR0_PE)
cc73a769dae68c Paolo Bonzini 2022-09-29  544  		kvm_set_cr0(vcpu, cr0 & ~(X86_CR0_PG | X86_CR0_PE));
cc6eb1e4699ff9 Paolo Bonzini 2022-09-29  545  

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

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